Technical field
[0001]
The present invention relates to a lap fillet arc welded joint.
The present application, on July 6, 2016, claiming priority based on Japanese Patent Application No. 2016-134334, filed in Japan, the contents of which are incorporated here.
BACKGROUND
[0002]
For example, in the field of automobile, for environmental protection, together with improved fuel efficiency through weight reduction of the vehicle body, increase collision safety has been demanded. Therefore, in order to achieve the improvement of weight reduction and crashworthiness of the vehicle body, as well as thinned members used in the vehicle body by using the high-strength steel sheet, such as by optimizing the vehicle body structure, various heretofore efforts have been made of.
[0003]
The underbody members of automobiles, overlapped fillet arc welding has been widely used, in addition to the usual static tensile strength, to withstand the forces repeatedly act, required to include a sufficient fatigue strength It is. In a typical lap fillet arc welding, lap as the plate surfaces of the two steel plates are opposed, the area of the end of one of the steel sheet (end face and the area in the vicinity), the plate surface of the other steel plate forming a weld bead by overlapping fillet arc welding and a region in the vicinity of the end portion of the one of the steel sheet in the region.
In the following description, if necessary, one of the steel sheet of the upper plate, said the other metal plate of the lower plate.
[0004]
Normally, the fatigue strength of the base material used in the welding member is increased in proportion to the strength of the steel sheet, the fatigue strength of the welded members, be increased strength of the steel sheet, it is necessarily known not to increase . This is a factor that has inhibited the weight of the vehicle body by the use of high-strength steel sheet.
[0005]
In general, as one of the factors governing the fatigue strength of the welded members, and stress concentration on the weld toe due to the shape of the weld bead. The weld toe, of the boundary between the steel and the weld metal, means a boundary portion of the side for supplying the welding wire during welding. Weld toe is, to become a discontinuous surface shape from the base material, it is believed stress is concentrated on the weld toe. In particular, typical fatigue cracks in the overlapped fillet arc corner superimposed manufactured by welding weld member is often generated from weld toe of the lower plate stress concentration (lower steel plate).
Therefore, the lower plate by smoothing the grinder finishing such surfaces of the weld toe (lower side steel), thereby reducing the stress concentration factor of the weld toe of the lower plate (bottom steel), fatigue strength It has been made to improve the.
[0006]
The lap fillet weld member that is frequently used in welded structures using thin steel plate, in the thickness direction of the steel sheet, is shifted and the plate thickness center axis of the plate thickness center axis and the other of the steel sheet of one of the steel sheet. Here, the thickness center axis and passes through the plate thickness direction of the center of the steel plate, means an axis extending in a direction perpendicular to the thickness direction of the direction and the steel plate along the weld line of the weld bead. In the following description, it referred to as "plate thickness center axis" according to this axis as required.
Thus, given a tensile force to both ends of the steel plate, it takes a large bending moment in the fillet weld, also concentrates stress in the root portion as well weld toe, sometimes broken. The root portion, of the boundary between the steel and the weld metal, the side for supplying the welding wire during the welding means the boundary portion of the opposite side.
[0007]
Patent Document 1 discloses that to perform a manner overlapping fillet arc welding as follows. First, folding the end of one of the steel plate (lower plate) downward. Then, the end face of the other steel plate (upper plate), is brought into contact with the bent portion of the plate surface of one steel plate. Then, fillet welding the abutting portion of the steel sheets. In Patent Document 1, by doing so, to reduce the deviation of the thickness center axis between the steel sheet, it is to be able to improve the strength of the welded joint.
[0008]
However, in the welded structure members of the actual steel sheet, the failure of the combination accuracy of springback and pre-welding member when press-molding a steel plate, often unintended gap is generated between the steel plates. That is, Patent Document 1, although the steel sheet each to be welded have been described to fillet welding after abutted, the actual welding structural member, as shown in FIG. 12, between the steel sheet 1210 and 1220 it is often welded in a state in which a gap 1230.
[0009]
In Patent Document 1, the thickness center axis of one of the steel sheet bending the end, the deviation amount in the thickness direction of the plate thickness center axis of the other of the steel sheet, the average value of the plate thickness of both 1 / if 2 or less satisfactory joint strength is to be obtained. However, the present inventors have, in a manner similar to that shown in Patent Document 1 to produce a meat arc welded joint corner overlaid with two steel plates, the axial force fatigue test applying a tensile load to both ends of the steel sheet was carried out, sufficient fatigue strength can not be obtained, there have been cases where the root portion is broken at an early stage. In Patent Document 1, the bending fatigue test is not applied load on the root portion, which evaluates only the fatigue strength of the weld toe.
In contrast, in the axial force fatigue test, the weld toe and the root portion becomes a stress concentration portions together by bending moment at the time of loading. Therefore, it is considered to have broken at higher becomes the root portion of the stress concentration factor. Here, although described as an example where the metal plate is a steel plate, above it, the same applies to the metal plate other than a steel sheet capable of producing lap fillet arc welded joint.
CITATION
Patent Document
[0010]
Patent Document 1: Japanese Laid-Open Patent Publication No. 9-141427
Summary of the Invention
Problems that the Invention is to Solve
[0011]
The present invention has been made in view of the above problems, even in a state where a gap between metal plates, providing meat arc welded joint corner stress superimposed concentration is small weld toe and root portion an object of the present invention is to.
Means for Solving the Problems
[0012]
(1) overlapped fillet arc welded joint according to one embodiment of the present invention comprises a first metal plate, a second metal plate, and the first metal plate and the junction of the second metal plate a lap fillet arc welded joint having a weld bead, said one end region of the first metal plate is bent, the weld bead, the second metal plate, said first metal in the area including the region between the bent and has regions of the plate, in a cross-sectional view of a cross-section perpendicular to the weld line of the weld bead, in a first direction, the bent of the first metal plate the position of the tip region which is overlapped with the one end region of the second metal plate, in a second direction, said the central axis of the region following the first of said folded and has a region of the metal plate deviation amount between the center axis of the one end side area of ​​the second metal plate, Serial and 1/2 times or less of the first metal plate and the average value of the thickness of the second metal plate, said first direction, the direction and the second metal along the weld line of the weld bead a plate thickness direction perpendicular to the direction of the plate, said second direction is a thickness direction of the second metal plate, weld toe of the first metal plate from the root portion of the second metal plate and the length of the joint length to the end twice or more the thickness of the second metal plate, the position of the weld toe of the first metal plate in the second direction is the in the range from 1 position to the second position, the first position is a position on the plate surface of the area following the bent and has a region of said first metal plate, said welded a position on the plate surface on the side where the bead is formed, the second position, the bent and has a region of said first metal plate Characterized in that Ku is the position of the central axis in the second direction of the area.
[0013]
Lap fillet arc welded joint consisting of the above-described configuration, even in a state in which a gap between metal plates, a small stress concentration of the weld toe and root portion.
[0014]
(2) According to another aspect of the present invention, the overlapped fillet arc welded joint according to the above (1), in a cross-sectional view of a cross-section perpendicular to the weld line of the weld bead, said first metal plate said bent by being region, the angle at which the bending angle of the plate surface of the second metal plate is not more than 35 ° more than 10 °, the joint length of the plate thickness of the second metal plate or less 4 times 2 times, the of the root portion of the first root portion of the metal plate a second metal plate, the distance in the second direction following the thickness of the second metal plate it may be.
[0015]
(3) According to another aspect of the present invention, the above (1) or (2) in the overlapped fillet arc welded joint according to the representative value of the joint length of the plate thickness of the second metal plate not less than 2 times, a representative value of the joint lengths may be definite on the basis of the joint length in a plurality of the cross section of the lap fillet arc welded joint.
[0016]
(4) According to another aspect of the present invention, the overlapped fillet arc welded joint according to any one of (1) to (3), the first metal plate and the plate of the second metal plate thickness may be 1.6mm or more 3.4mm or less.
[0017]
According to another aspect of (5) the present invention, in the above-mentioned overlapped fillet arc welded joint according to any one of (1) to (4), the first metal plate and the second metal plate, it may be a galvanized steel sheet.
Effect of the invention
[0018]
According to the present invention, even in a state in which a gap between metal plates, it is possible to provide meat arc welded joint corner stress superimposed concentration is small weld toe and root portion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019]
[1] Figure 1 is a diagram illustrating folding of the thickness center axis of the plate thickness center axis and overlapping steel steel, an example of the analysis result of stress in the absence of displacement in the sheet thickness direction, FIG. 1 ( a) shows the shape (initial shape) before applying the tensile load, FIG. 1 (b) shows the shape (shape after deformation by tensile load) after applying a tensile load, FIG. 1 (c) tensile It shows the distribution of the stress of each part after a load is applied.
FIG. 2 is the thickness center axis of overlapping steel sheets, folded to the thickness center axis of the steel sheet, displaced by half by weld toe side of the mean value of the thickness of the folded sheet and overlaid steel plates is a diagram illustrating an example of an analysis result of a stress when it is, FIG. 2 (a) shows the shape (initial shape) before applying the tensile load, FIG. 2 (b) shape after being subjected to tensile load It shows the (tensile shape after deformation by the load), FIG. 2 (c) shows the distribution of stresses in each section after applying a tensile load.
FIG. 3 is the thickness center axis of overlapping steel sheet, with respect to the thickness center axis of bending steel plate, are offset by 1/2 the root portion side of the bent steel sheet and the average value of the thickness of the overlapping steel plate is a diagram illustrating an example of an analysis result in the case, FIG. 3 shows the (a) is before applying tensile load shape (initial shape), by the shape (tensile load after multiplied by FIG. 3 (b) tensile load showing the shape after deformation), FIG. 3 (c) shows the distribution of stresses in each section after applying a tensile load.
[4] FIG. 4 is a schematic diagram showing an example of a member which is produced by overlapping fillet arc welding is performed, FIG. 4 (a) is a perspective view showing an example of the configuration of the member, FIG. 4 (b) is a diagram showing an example of the case in plan view from the top surface of the member shown in Figure 4 (a).
FIG. 5 is a schematic diagram for explaining an example of lap fillet arc welded joint is a sectional view viewed in cross section the cross section perpendicular to the weld line.
FIG. 6 is a schematic diagram for explaining an example of overlapping corner model meat arc welded joint used in the study of joint length, is a diagram assuming a cross section perpendicular to the welding line .
[7] FIG. 7 is a graph showing an example of the relationship between the stress concentration factor and lap steel position of the root portions of the overlapped steel.
[8] FIG. 8 is a schematic diagram showing an example of the distribution of lap fillet arc welded joint of each part of the stress, FIG. 8 (a), bending angle alpha = 45 °, superimposed steel position x = 1. shows the distribution of the condition of 2 mm, Figure 8 (b) shows bending angle alpha = 30 °, the distribution of the condition of the overlapping steel plate position x = 1.8 mm.
[9] FIG. 9 is a graph showing the stress concentration factor of the root portion of the overlapping steel plate, an example of the relationship between the value divided by the plate thickness of the steel sheet overlaid joint length.
[10] FIG 10 is a schematic diagram showing a comparative example of lap fillet arc welded joint, FIG. 10 (a) Meat arc welded joint corner gap is large overlapping route section, the cross section perpendicular to the welding line the is a sectional view viewed in cross section, FIG. 10 (b) meat arc welded joint corner lap is large junction length is a sectional view viewed in cross section the cross section perpendicular to the weld line.
[11] FIG 11 is a schematic diagram for explaining an example of the relationship between the bending angle and the overlapping steel plate position.
[12] FIG 12 is a schematic diagram showing that a gap is produced steel in making the lap fillet arc welded joint is a sectional view viewed in cross section the cross section perpendicular to the weld line.
[13] FIG 13 is a schematic diagram for explaining an example of a method of two-pass welding, FIG. 13 (a) and FIG.. 13 (b), corner superimposed was applied by each two-pass weld arc welding joint is a sectional view viewed in cross section the cross section perpendicular to the weld line.
DESCRIPTION OF THE INVENTION
[0020]
(Finding the present inventors have obtained)
First, the findings of the present inventors have obtained. The present inventors have bent one end side region of one of the steel plate of the two steel plates, the lower plate one of the steel sheet such, the other steel plate as the top plate, the meat arc welding corner superimposes the two steel plates were investigated in detail lap fillet arc welded joint is produced by.
[0021]
Incidentally, in the following description, if necessary "steel plate (lower plate) formed by bending the region of one end side" is referred to as "bent steel sheet", as necessary "the other steel plate (upper plate)" "piled It is referred to as a steel plate. "
In the following description, unless otherwise specified, just when called "lap fillet arc welded joint" or "overlapped with folded steel fillet arc welded joints", of "two steel plates bending one area of one end of the steel plate, the lower one of the steel plate the plate, the other steel plate as the top plate, overlaid fillet arc welded joint is produced by overlapping fillet arc welding the two steel plates " shall refer to a conventional lap fillet arc welded joints without a bent steel sheet is referred to as "common overlapping fillet arc welded joints."
[0022]
First, the present inventors estimated the stress concentration factor for the tensile load of lap fillet arc welding joint thickness is produced by the steel sheet of 2mm in FEM (FiniteElementMethod) analysis. 1 to 3 are diagrams showing an example of the results.
1 to 3, FIG. 1 (a), 2 (a) and 3 (a) shows before applying the tensile load shape (initial shape). FIG. 1 (b), the FIG. 2 (b) and 3 (b) shows a tensile shape after a load is applied (the shape after deformation by tensile load). FIG. 1 (c), the FIGS. 2 (c) and 3 (c) shows the distribution of stresses in each section after applying a tensile load.
Here, (the ends of the bent steel plate side, overlapping edge portions of the steel plate side) overlapping corners both end portions of meat arc welded joint when adding a tensile load of 30MPa were FEM analyzed on.
[0023]
Figure 1 is a bending angle α is the 45 ° bending an example of the analysis result of stress in the absence of displacement of the thickness center axis and superimposed thickness center axis in the thickness direction of the steel sheet (Z-axis direction) of the steel sheet is a diagram illustrating a.
Here, the bending angle alpha, which is formed (acute side) angle between the plate surface and the plate surface of the overlapping steel plate region bent the bent steel plate (see Figure 5).
[0024]
In the present embodiment, the thickness center axis and passes through the plate thickness direction of the center of the steel plate, along the weld line of the weld bead (Y-axis direction, both the longitudinal direction referred to) and steel plate thickness direction (Z-axis it is an axis extending in a direction) and perpendicular direction (X axis direction). Further, the thickness center axis of bending steel sheet is intended to refer to the thickness center axis of the area following the area which has been bent the bent steel plate (overlapping steel plate and substantially parallel regions).
[0025]
As shown in FIG. 1 (c), the stress (equivalent stress) in folded steel plate, maximum at its weld toe, the value was 32 MPa. On the other hand, the stress in the overlapped steel (equivalent stress) is maximum at the root portion, the value was 41 MPa. Thus, in the thickness direction (Z axis direction), when there is no deviation in the thickness center axis of the plate thickness center axis and overlapped steel bending steel sheet, next to the stress of the root portion of the overlapping steel plate is 41 MPa, increased slightly although, (maximum value) of the stress concentration factor of the root portion of the overlapping steel plate is as small as 1.36.
Accordingly, as shown in FIG. 1, the lap fillet arc welded joint, performing the superimposed fillet arc welding by opposing the plate surface together without bending the common overlapping corner areas of meat arc welded joint (one end side to weld joint) produced by, it expected significant improvement in fatigue strength.
[0026]
Figure 2 is a bending angle α is the 45 °, the thickness center axis of overlapping steel sheets, folded to the thickness center axis of the steel sheet, folded sheet and ½ weld toe of the thickness of the average value of the superimposed steel plates is a diagram illustrating an example of an analysis result of a stress in the case are offset on the end side. Because the thickness of the bent steel plate and overlaid steel are both 2 mm, 1/2 folding average value of the thickness of the steel sheet and overlaid steel plates is 1 mm.
As shown in FIG. 2 (c), the stress (equivalent stress) in folded steel plate, maximum at its weld toe, the value was 53 MPa. On the other hand, the stress in the overlapped steel (equivalent stress) is maximum at the root portion, the value was 93 MPa.
[0027]
Thickness center axis of overlapping steel sheets, when the image is shifted weld toe side with respect to the thickness center axis of bending steel sheet, the addition of a tensile load to both ends of lap fillet arc welded joint, Figure 2 ( as shown in b), the bent steel sheet deforms into a convex shape toward the weld toe side, piled steel sheet is deformed into a convex shape toward the root portion side. As a result, the stress of the root portion of the weld toe and overlapped steel bending steel sheet is increased. Stress concentration factor of the weld toe of the bent steel plate (maximum value) of 1.8 (maximum value) of the stress concentration factor of the root portion of the overlapped steel sheets was 3.1.
Thus, the thickness center axis of overlapping steel sheets, when the image is shifted weld toe side with respect to the thickness center axis of bending steel sheet, than weld toe of the bent steel sheet, the root of the overlapping steel plate If parts exhibits a higher stress concentration. Stress concentration factor of the general lap fillet arc welded joint is about 4. Therefore, the root portion of the overlapping steel plate it can be seen that the stress concentration factor close to it.
[0028]
Figure 3 is a bending angle α is the 45 °, the thickness center axis of overlapping steel sheets, folded to the thickness center axis of the steel sheet, folded ½ root portion of the steel sheet and the average value of the thickness of the overlapping steel plate is a diagram illustrating an example of an analysis result of a stress in the case are shifted to the side.
As shown in FIG. 3 (c), the stress (equivalent stress) in folded steel plate, maximum at the plate surface of the root portion side, the value was 53 MPa. On the other hand, the stress in the overlapped steel (equivalent stress) is maximum at its weld toe, the value was 64 MPa.
[0029]
Thickness center axis of overlapping steel sheets, when the image is shifted root portion side with respect to the thickness center axis of bending steel sheet, the addition of a tensile load to both ends of lap fillet arc welded joint, and FIG. 3 (b) as shown in, the folded steel sheet deforms into a convex shape toward the root portion side, piled steel sheet is deformed into a convex shape toward the weld toe side. That is, the steel sheet is deformed in the opposite direction to the shape shown in FIG. 2 (b). Then, it can be seen that the stress concentration at the root portion of the overlapping steel plate is eliminated.
Also, the stress concentration factor (maximum value) of the plate surface of the root portion side of the bent steel sheet 1.8, (maximum value) of the stress concentration factor of the weld toe of the lap steel was 2.1. Thus, the thickness center axis of overlapping steel sheets, who when the image is shifted root portion side with respect to the thickness center axis of the bending steel sheet, than if the image is shifted weld toe side, stress concentration it can be seen that the coefficient becomes small.
[0030]
From the above, the thickness center axis of overlapping steel sheets, folded when shifted to the weld toe side with respect to the thickness center axis of the steel sheet (i.e., the case of FIG. 2) root section stress concentration of the overlapping steel plate to lower the coefficients, it is found important in fatigue strength of lap fillet arc welded joint.
Note that in FIGS. 2 (c) and 2 FIG. 3 (c), the indicating the boundary of the region as a more high stress 50MPa by the solid line. FIG. 1 (c) region that indicates a more high stress 50MPa in did not exist. However, in FIGS. 2 (c) and 2 FIG. 3 (c), there is a region where the above high stress 50 MPa, it can be seen that the stress is large in the vicinity of the weld toe and route section.
[0031]
Upon producing meat arc welded joint corner lap, if the position is deviated in the thickness direction of the plate thickness center axis of the two steel plates has been found to stress concentration factor of the root portion of the upper plate is highest . Therefore, the present inventors have considered that it is necessary to lower the stress concentration factor of the root portion of the overlapping steel plate. Accordingly, the present inventors have found that the thickness center axis of overlapping steel sheet, than if the person when the image is shifted root portion side with respect to the thickness center axis of the bending steel sheet is shifted to the weld toe side also, by noting the long length of the weld in a direction perpendicular to the thickness direction of the direction and the overlapping steel plates along a weld line of the weld bead.
Then, in order to reduce the stress concentration factor of the root portion of the overlapping steel plate it is effective to increase the length of the welded portion in a direction perpendicular to the thickness direction of the direction and overlapping steel plates along a weld line of the weld bead It inspired that there.
[0032]
The present inventors have found that on the basis of this idea, it is effective to increase the joint length. Here, the junction length, as indicated by L1 in Fig. 5, in the X-Z cross section, the length of the line connecting the weld toe 530 and the root portion 560.
[0033]
As described above, the transfer of load between the steel sheet and folding the steel sheet overlaid by a longer joint lengths L1 becomes smooth, it is considered possible to reduce the stress concentration factor of the root portion of the overlapping steel plate. In order to increase the joint length L1, it is necessary to increase the distance between the bent steel plate and overlapping side steel.
When the folding steel largely bent, the gap between the root portion of the root portion and the overlapping steel plate bent steel sheet is too large. Then, corner flowed molten metal from the gap during meat arc welding, in the one-pass welding, if appropriate weld bead can not be formed. Therefore, after increasing the junction length L1, to keep a good bead shape was found that it is preferable to limit the bending angle alpha.
[0034]
As described above, the present inventors have overlapping distance between the weld toe of the steel sheet and folding the root portion of the overlapping steel plate, i.e., by increasing the joint length L1, with respect to the thickness center axis of the bending steel thickness center axis of the steel sheet, even if shifted to the side (upper side) of the weld toe is formed, it found that can reduce the stress concentration factor of the root portion of the overlapping steel plate. Further, by limiting the bending angle alpha, and a gap of the root portion of the folded sheet and overlaid steel plates, while a longer joint lengths L1, found that it is possible to suppress the welding defects during one pass welding . The embodiments described below, has been made based on the above findings.
[0035]
Hereinafter, with reference to the drawings, an embodiment of the present invention. The present invention, it is obvious that the invention is not limited to the following embodiments.
[0036]
The present embodiment will be described as an example where the metal plate is a steel plate, the metal plate may not be steel. Figure 4 is a diagram showing an example of a member which is produced by being subjected to overlapped fillet arc welding method of this embodiment described below.
Member shown in FIG. 4, for example, is a frame member of the chassis of the motor vehicle is not limited to a frame member of the chassis of the motor vehicle. 4 (a) is a perspective view showing an example of the configuration of the member 400. 4 (b) is a diagram showing an example of a top member 400 shown in FIG. 4 (a) (surface weld bead 430 is formed).
[0037]
4 (a), the member 400 is constructed by joining the steel plate 410 by welding bead 430, 440 are formed by overlapping fillet arc welding. Thus, the weld bead 430, 440 become the joint of the steel plate 410, 420.
As shown in FIG. 4 (a), the shape of the plate width direction of the steel sheet 410 and steel plate 420 (Y-axis direction) in a cross section perpendicular (X-Z cross section), which is U-shaped. That is, the cross-sectional shape of the steel sheet 410 and steel plate 420, as shown in FIG. 4 (a), in X-Z cross section, parallel to the Z axis region and a region parallel to the continuous vital X-axis and the area a. In steel 410 or steel 420 has a shape having one end protruding vital than the other end portion of the steel plate, the tip portion of the protruding end portion bent inwardly of the member 400.
[0038]
Shapes, such as steel plates 410 and 420, rather than bending, can be formed by pressing. Incidentally, members for which overlapped fillet arc welding method of this embodiment is performed, which will be described later, it is not limited to a member 400 as shown in FIG.
Further, with respect to member produced by performing the bending, it may be subjected to lap fillet arc welding method of this embodiment described below.
[0039]
Figure 5 is a diagram showing an example of lap fillet arc welded joint according to the present embodiment. Figure 5 shows a (plane including the X-axis and Z-axis) X-Z cross section in the region and the region in the vicinity of the weld bead 430 shown in FIG. 4 is formed. Here, X-Z cross section is a cross section perpendicular to the Y axis.
[0040]
Incidentally, the side lap fillet arc welding joint weld bead 440 shown in FIG. 4 is formed, a superposed fillet arc welded joint shown in FIG. 5, the plate width direction of the steel sheet 410, 420 (Y-axis direction) a relationship of rotational symmetry of the rotation axis. Thus, is omitted here, the weld bead 430 describes a lap fillet arc welded joint on the side which is formed in detail, corners superposed on the side where the weld bead 440 is formed a detailed description of the meat arc welded joint .
In the example shown in FIG. 5, a steel sheet folded steel 410, steel 420 is overlaid steel plates. In the following description, if necessary, referred to as a folded steel plate 410 to the steel plate 410, referred to as steel sheets 420 stacked steel plate 420. In FIG. 4, in the side of lap fillet arc welding joint weld bead 440 is formed, it becomes the steel sheet folded steel 420, steel 410 is overlaid steel plates.
[0041]

As shown in FIGS. 4 and 5, folded at one end of the steel plate 410 area (positive direction side end region of the X axis), It is bent. On the other hand, the region of one end of the overlapping steel plate 420 (the negative direction side of the X-axis) are not bent.
Further, an area following the area which has been bent the bent steel plate 410 (the region 410b of the bent steel plate 410 of FIG. 5), (a region of overlapping steel plates 420 in FIG. 5 420a) one end region of the overlapping steel plate 420 is substantially parallel it is preferable that.
[0042]
5, folding the region an area 410a which is bent with one end of the steel plate 410, and the area 420a of the one end region of the overlapping steel plate 420. Also, the area following the region 410a which is bent with folded steel plates 410 and region 410b.
[0043]
Position in the X-axis direction of the bent region 410a of the steel sheet 410 tip (positive direction side of the end of the X axis), overlaps with any of the X-axis direction position of the region 420a lap steel 420. In other words, in the X-axis direction, the position of the tip of the region 410a of the bent steel plate 410 overlaps with the area 420a of the steel sheet 420 overlaid.
[0044]
In the region 420a of the stacked steel plates 420, the position of the Z-axis direction of at least a partial region of the overlapping steel plate 420 may overlap with either of the position in the Z-axis direction of a region 410a of the bent steel plate 410.
[0045]
Incidentally, it is shown by way in FIG. 4 and FIG. 5, the Z-axis direction position of a partial region of the overlapping steel plate 420, a case where overlap with any of the positions in the Z-axis direction of the region 410a of the bent steel plate 410 as an example.
Thickness of the bent steel plate 410 and stacked steel plate 420 and, or the length of the region 410a of the bent steel plate 410, depending on the bending angle α such as the position in the Z-axis direction of the entire area of the overlapping steel plate 420, bending of the bending steel 410 it is may overlap with any of the positions in the Z-axis direction of the region 410a has.
[0046]
In the following description, it referred to as "region of the bent steel plate 410 410b (FIG region parallel to the X axis of the bent steel plate 410 of 5)" as needed, "inclined non region 410b of the bent steel plate 410". Overlaid steel plates 420 at one end, a region 410b substantially parallel to the region of bending steel plate 410, i.e. if it has a region 420a, may be bent in the other regions. The other area, for example, a portion parallel to the Z axis of the superimposed steel plates 420 in FIG. Further, bent steel plate 410, in addition to the region of one end thereof, may be bent in the other regions. The other area is a portion parallel to the Z axis of the bent steel plate 410 of FIG.
[0047]

5, the deviation amount between the thickness center axis of the region of the thickness center axis and overlapping steel plate 420 of the bent steel plate 410 420a are weld toe 530 and 540 are formed that side in any of the even side (positive direction of Z-axis) and the root portion 550 and 560 are formed (the negative direction side of the Z axis), bending the plate thickness t of the steel sheet 410 PB plates and overlaid steel plates 420 the thickness t PL is 1/2 times or less the average value of.
[0048]
Here, the amount of deviation between the thickness center axis of the plate thickness center axis and overlapping steel plate 420 of the bent steel plate 410, the area of ​​the Z-axis in the direction of bending superimposed on the thickness center axis 510 of the region 410b of the steel sheet 410 steel 420 the length between the thickness center axis 520 of 420a. As described above, the thickness center axis, the X-Z cross section refers to the axis extending the center in the thickness direction of the steel sheet in a direction parallel to the surface of the street and the steel sheet.
[0049]
In Figure 5, the plate thickness center axis 520 of the region 420a of the overlapping steel plates 420, to the thickness center axis 510 of the region 410b of the bent steel plate 410, the positive side (Z-axis weld toe 530 and 540 are formed indicates taking a case in which the deviation of the direction) as an example. As long as the range of the deviation of the thickness center axis 510, 520 of the bent steel plate 410 and stacked steel plate 420 described above, the thickness center axis 520 of the region 420a of the overlapping steel plate 420, the plate thickness of the region 410b of the bent steel plate 410 with respect to the central axis 510 may be offset in the side (negative direction side of the Z-axis) of the root portion 550 and 560 is formed.
[0050]
In the example of overlapping fillet arc welded joint shown in FIG. 5, and the negative direction of the Z axis is a direction that is bent region 410a of the bent steel plate 410. In other words, the negative direction of the Z axis, relative to the superimposed steel plates 420, the tip region 410a of the bent steel plate 410 is the direction to the position.
Further, folding the steel plate 410 may be referred upper surface of the positive direction side of the Z-axis, the negative direction side of the Z axis and the lower surface, the superimposed steel plates 420, the positive direction of the Z axis upper side surface of the negative direction side of the Z-axis may be referred to as lower surface. That is, in the example of lap fillet arc welded joint shown in FIG. 5, on the upper surface of the bent steel plate 410, weld toe 530 and root portion 550 is located. Also, the position weld toe 540 on the upper side surface of the stacked steel plates 420, route 560 on the underside of the overlapping steel plate 420 is located.
[0051]
Shift amount of the thickness center axis of the bent steel plate 410 and stacked steel plate 420, the plate thickness t of the bent steel plate 410 PB thickness t of the overlapping steel plate 420 PL exceeds 1/2 times the average value of the overlaid fillet arcs If the load of the tensile load or the like is applied to the welded joint, lap fillet arc welded joint is largely out-of-plane deformation. Therefore, the thickness t of such order to suppress the out-of-plane deformation occurs, the amount of deviation of the thickness center axis of the bent steel plate 410 and stacked steel plate 420, bent steel sheet 410 PB thickness t of the overlapping steel plate 420 PL it is preferred to 1/2 times or less of the average value.
From the viewpoint of reducing the amount of deviation of the thickness center axis than typical lap fillet arc welded joint, or may be in place of the "1/2 times or less" adopted "less than 1/2" .
[0052]

FIG. 6 is a diagram showing an example of the overlapping corner model meat arc welded joint used in the study of joint length L1. Also in FIG. 6, similarly to FIG. 5, shows the X-Z cross section of the bent steel plate 610 and stacked steel plate 620.
Here, the plate thickness t of the bent steel plate 610 PB thickness t of the overlapping steel plate 620 PL and is intended both equal 1.8 mm. Further, the bending of the inclined non region of the steel sheet 610 thickness center axis 640 of the overlapped steel 620 with respect to the thickness center axis 630, the side weld toe 650 and 660 are formed (the Z-axis positive direction side), the thickness t of the bent steel plate 610 PB so that only half a position shifted in a state of fixing the position of the folding steel 610 and overlaid steel plates 620, the folding steel 610 and overlaid steel plates 620 It was assumed to place.
[0053]
Further, in FIG. 6, folding the one end of bent and has a region area 610a of the steel plate 610, and the area 620a of the one end region of the overlapping steel plate 620. Further, a region following the bent of folded steel plate 610 region 610a and region 610b.
[0054]
The arrangement described above, perpendicular to the bending angle α and, X-axis direction (direction along the weld line of the weld bead 430 (Y-axis direction of the overlapping steel plate 620) and the thickness direction of the stacked steel plates 420 (Z-axis direction) by changing the position of the direction), the most stress joint shape that can reduce the stress concentration factor of the root portion 680 of the concentration to overlapping steel plates 620, was investigated by performing the analysis by FEM.
[0055]
Here in order to simplify the analysis by FEM, as shown in FIG. 6, the position of the weld toe 650 of the bent steel plate 610, and the position of the origin of the bent portion of the bent steel plate 610 (inflection point). Also, the position of the weld toe 660 of the overlapping steel plate 620, the position of the upper end (the positive direction side of the end of the Z-axis) of the end of the overlapped steel sheets 620 (front end), the position of the root portion 680 of the overlapped steel 620 and the position of the lower end of the end (tip) of the overlapping steel plate 620. Further, the root portion 670 of the bent steel plate 610, bent a on the plate surface of the area is bent the steel sheet 610, arranged in overlapping steel plate 620 and the side facing the plate surface, the position of the X-axis direction were the same position as the position in the X axis direction of the end (tip) of the overlapping steel plate 620.
[0056]
Under the above conditions, the bending angle α, 45 °, 30 °, 20 °, with varying the 10 °, the position x of the X-axis direction of the end (tip) of the overlapping steel plate 620 (in mm) by changing the in each state, by performing the analysis by FEM, overlapped fillet arc welded joint (bending steel sheet 610 overlaid steel plates 620, and the weld bead 690) and the stress of the root portion of the calculated.
Here, FIG as the value of the position x in the X-axis direction, the position as a starting point bending at the beginning of bending steel 610 0 (zero, x = 0) was the was (described above in one end of the overlapping steel plate 620 (the tip) in 6, the position is as a starting point bending at the beginning of bending steel sheet 610 is the same position as the position of the weld toe 650 of the bent steel plate 610). Then, the position of one end (tip) of the overlapping steel plate 620 (farther from the bending steel 610) positive as shifted in the direction of the X-axis value of the position in the X-axis direction of the end of the overlapped steel sheets 620 (front end) is made larger to. In the following description, referred to as "overlapping X-axis direction position of one end (tip) of the steel sheet 620" as needed "lap steel position x". 7 to 9 results graph of the analysis by the above-described FEM.
[0057]
Figure 7 is a graph showing an example of the relationship between the stress concentration factor and piled steel position x of the root portion 680 of the overlapping steel plate 620. As shown in FIG. 7, in any of the bending angle alpha, the larger the value of the overlapping steel plate position x, the stress concentration factor of the root portion 680 of the overlapped steel sheets 620 is can be seen that small.
8 is a diagram showing an example of the distribution of lap fillet arc welded joint of each part of the stress. 8 (a) is bending angle alpha = 45 °, it shows the distribution of the condition of the overlapping steel plate position x = 1.2 mm, FIG. 8 (b), bending angle alpha = 30 °, superimposed steel position x = 1 It shows the distribution of the conditions of .8mm.
[0058]
These results, superimposed steel position x is larger (i.e. the length in the X-axis direction of the junction is long) it is believed to transfer loads between the steel plate 620 overlapping the bent steel plate 610 becomes smooth.
[0059]
Weld toe of up to 650 the length of the steel plate 610 bent from the root portion 680 of the overlapped steel sheets 620 (junction length L1), as an indicator of the length of the X-axis direction of the joint, the root portion 680 of the overlapped steel 620 the result of re-organizing the stress concentration factor shown in FIG. Figure 9 is a stress concentration factor of the root portion 680 of the overlapped steel 620, thickness t of the overlapped joint portion length L1 steel 620 PL is a diagram showing an example of the relationship between divided by.
[0060]
As shown in FIG. 9, in the bending angle α and lap steel position junction regardless x length L1, it can be seen that organize stress concentration factor of the root portion 680 of the overlapping steel plate 620. The joining portion length L1 is the thickness t of the overlapping steel plate 620 PL becomes less than 2 times the, it is seen that the stress concentration factor of the root portion 680 of the overlapping steel plate 620 rapidly increases.
Therefore, the joint portion length L1, the thickness t of the overlapping steel plate 620 PL 2 times or more (L1 ≧ 2 × t PL by a), generally about 2 stress concentration factor of the root portion 680 of the overlapped steel 620 , i.e., it can be seen that it is possible to suppress the half of the common overlapping fillet arc welded joint. The present inventors have confirmed that even by changing the steel type and plate thickness of conditions such trend is illustrated.
[0061]
The upper limit of the junction length L1 is not particularly limited, from the viewpoint of securing sufficient padding in lap fillet arc welding, for example, the thickness t of the overlapping steel plate 620 PL than 5 times (L1 ≦ 5 × t PL preferable to be).
[0062]
From the above, in the present embodiment, the thickness t of the overlapped steel sheets 420 a junction length L1 PL is more than twice the. Here, the junction length L1 of the weld bead 430 may vary depending on the location of the weld bead 430. In such a case, it is preferable to employ the representative value as the junction length L1 of the weld bead 430.
In the present embodiment, for example, as shown in FIG. 4 (b), preferably the average value of the joint length L1 at positions 461-466 of the six, a representative value of the junction length L1 of the weld bead 430 . Position 461 is a (relative moving direction of the welding wire for welding planned portion) to 15mm apart position from the welding start position 451 the traveling direction of the welding of the weld bead 430. Position 462 is a position apart 15mm in opposite directions to the welding from the welding end position 452 of the weld bead 430. Position 463-466 is in the range of 5 equally divided positions in the Y axis direction to both ends positions 461 and 462 (the direction along the weld line of the weld bead 430).
[0063]
In the case where the welding start position of the weld bead and the welding end position overlap each other also, as mentioned above, the bonding head of the weld bead the average value of the joint length L1 in the X-Z cross-section at the six position is can be a representative value of L1.
The representative value of the junction length L1 of the weld bead 430 is not necessarily limited to those described above. For example, it is possible to use the median instead of the average value. Also, without the 5 equal parts, n equal parts (n is an integer of 2 or more) may be calculated as.
[0064]

In the present embodiment, the bending position in the Z-axis direction of the weld toe 530 of the steel plate 410 (thickness direction of the stacked steel plate 420), from a first position the second in the range of up to position.
[0065]
Here, the first position is bent at a position on the plate surface region 410b of the steel sheet 410, the weld bead 430 on the plate surface of the side to be formed (Z-axis positive direction side of the plate plane) which is the position. The first position may be the position of the region where the weld bead 430 is not formed. Second position, in the Z axis direction, the position of the thickness center axis 510 of the region 410b of the bent steel plate 410.
In the following description, "a plate surface region 410b of the bent steel plate 410, the plate surface of the side where the weld bead 430 is formed (the plate surface of the positive direction side of the Z-axis)" as needed referred to as "region surface 410b of the bent steel plate 410".
[0066]
Weld toe 530 of the bent steel plate 410, if on the surface of the region 410b of the bent steel plate 410, it is possible to smooth the shape of the weld toe 530 preferably. On the other hand, weld toe 530 of the bent steel plate 410 is bent when located in a region that is bent of a steel sheet 410, indentations occur in weld toe 530, stress concentration occurs in the portion where the recess has occurred.
Position in the Z axis direction of the weld toe 530 of the bent steel plate 410 is, from the position of the thickness center axis 510 of the region 410b of the bent steel plate 410, bending the negative direction of the distal end side (Z-axis of the region 410a of the steel sheet 410 When located on the side), becomes large and complicated shape of the recess, there is a possibility that a large out-of-plane deformation occurs.
[0067]
In the present embodiment from the above, the position in the Z axis direction of the weld toe 530 of the bent steel plate 410 from the position of the surface of the region 410b of the bent steel plate 410 (i.e., the first position), bent steel plate 410 position of the region 410b of the thickness center axis 510 (i.e., the second position) in the range of up to.
[0068]
In the above description, , , and by defining the , overlapping corners root portion 550 of the wall joint showed that can reduce the stress concentration factor of 560.
By performing the welding of a plurality path as welding thick steel plates, without providing any special restriction on the shape of the joint, welding satisfying these conditions is possible. However, for example, for the automotive members are important for productivity often be produced in one pass welding, it is required to perform stable welding causing no outflow and burn defects the molten metal. Thus, as follows, , it is preferable to define the , and .
[0069]

In the present embodiment, as shown in FIG. 5, be produced welded joints in a state where a gap and the steel sheet 420 overlapping the bent steel plate 410, stress concentration in the root portion 550 and 560 It has proposed a method that can be reduced. However, the gap g between the root portion 550 and a root portion 560 (the distance between the root portion 550 and root portion 560 in the thickness direction of the stacked steel plates 420 (Z-axis direction)) becomes excessively large, in FIG. 10 (a) as shown, welding time in the molten metal flows out from the gap g (see white arrows in FIG. 10 (a)), it becomes welding defect. Therefore, in order to perform good welding by one-pass welding, it is necessary to provide an upper limit for the gap g between the root portion 550 and a root portion 560.
[0070]
According to our experience, in a typical lap fillet arc welded joints without a folded steel sheet, the gap of the root portion is overlapped at least 1.5 times the thickness of the steel sheet to become welding defect. The lap fillet arc welded joints with bent steel plate 410 according to this embodiment, since the region 410a of the bent steel plate 410 is inclined with respect to the overlapping steel plate 420, a gap g between the root portion 550 and root portion 560 even 1.5 times the thickness of the overlapping steel plate 420, the molten metal is easily flows out from the gap g between the root portion 550 and a root portion 560.
Therefore, in order to realize a stable welding is the thickness t of the steel sheet 420 overlapping the upper limit of the gap g between the root portion 550 and a root portion 560 PL is preferably set to. That, (g ≦ t PL preferably satisfy the relationship between).
[0071]

in terms of the above-mentioned , the thickness t of the overlapping steel plate 420 the lower limit of the junction length L1 PL 2 times (i.e., L1 ≧ 2 × t PL and) by showed that can reduce the stress concentration factor of the root portion 550 and 560. As described in the section , the upper limit of the junction length L1 in terms of reducing the stress concentration factor of the root portion 550 and 560 is not particularly limited. However, it is preferable to set the upper limit to the junction length L1 from the viewpoint of weldability for actually producing a welded joint in a single pass.
[0072]
As shown in FIG. 10 (b), in order to increase the joint length L1 needs to increase the width of the weld bead 430 to increase the heat input (length in the X-axis direction). However, when excessively increasing the heat input (see white arrows in FIG. 10 (b)) or fall bent steel plate 410 is melted, perforated defects occur weld toe 540 of the overlapping steel plate 420 side there is a case to be or. Thickness t of the overlapped joint portion length L1 steel 420 PL 4 times less (i.e., L1 ≦ 4t PL ) With, it was confirmed that these welding defects does not occur.
Therefore, the thickness t of the overlapping steel plate 420 the upper limit of the junction length L1 PL is preferably set to four times. That, (L1 ≦ 4t PL preferably satisfy the relationship between). In terms of , the upper limit of the junction length L1 5 × t PL was a, which is a value obtained by assuming welding in multiple paths, given the one-pass welding , the upper limit of the junction length L1 4 × t PL is preferably.
[0073]

affect bending angle α also welding of the joint portion length L1 and the root portion 550 and 560 of the gap g as well as bent steel plate 410. If bending angle α is large, as shown in FIG. 10 (a), comprising welding defect is likely to occur due to flow out of the molten metal for clearance g root portion 550 and 560 tends to be large.
On the other hand, bent at a small state angle alpha, bent steel plate 410 and the shift amount of the thickness center axis of the overlapped steel 420, the thickness t of the bent steel plate 410 PB thickness t of the overlapping steel plate 420 PL of the average value of 1 / If you try to 2 times or less, as shown in FIG. 10 (b), it is necessary to perform a large weld joint length L1.
[0074]
However, as described in the section , in order to obtain a larger weld bead 430 of the junction length L1, it is necessary to increase the welding heat input broaden the weld bead 430, welding defect occurs involved. Further, 1 the path bending angle α is small when performing welding, folding Z-axis direction position of the weld toe 530 of the steel plate 410, a region which is bent the bent steel plate 410 front end side (the Z axis located in the negative direction side), weld toe 530 of the bent steel plate 410 is likely to become a stress concentration portion.
To avoid these problems, bending angle α preferably set to 35 ° or less 10 ° or more.
[0075]
In one-pass welding, to verify the proper range of the bending angle α for performing a stable welding, the present inventors have a plurality of overlapping fillet arc welded joints with different bending angles α and piled steel position x It was produced. Welding method, it was generally Parusumagu welding method used in the frame member of the chassis of the motor vehicle. Further, here, with a steel sheet having a thickness of 3.2 mm. The results are shown in Figure 11. 11 (here, xmm / t overlapping steel plate position x PL mm are normalized by (thickness
[0076]
As shown in FIG. 11, the bending angle α and overlaid steel position x / t PL when both the is large, folding gap increases between the steel plate 410 and the overlapping steel plate 420, the molten metal flows out from the gap and it will become welding defects (see a portion indicated as "outflow of molten metal" in FIG. 11). The preferred ranges outflow of molten metal does not occur, approximately "x / t PL is a range satisfying the ≦ -0.125 × α + 6.875".
[0077]
Also, small bending angle alpha is (alpha <10), superimposed steel position x / t PL is large (x / t PL > if 5), the Z-axis direction position of the weld toe 530 of the bent steel plate 410 , so that the inside of the bent of folded folding steel 410 than the position of the thickness center axis 510 of the inclined non region 410b of the steel sheet 410 region 410a (the positive direction side of the Z axis), a high heat input setting the welding conditions, perforated defective folding steel 410 had occurred (see a portion indicated as "bending range of the steel sheet side stop end position" of FIG. 11).
[0078]
Furthermore, bending angle α and overlaid steel position x / t PL if both is small, will be steel 420 superimposed folded steel plate 410 is bumped, described in the section described above reference (bent steel plate 410 for deviation from the thickness center axis of the region 420a in the region 410b of the thickness center axis and overlapping steel 420, the thickness t of the bent steel plate 410 PB thickness t of the overlapping steel plate 420 PL average of of that to 1/2 or less) can not be satisfied the condition that (see a portion indicated as "out of the range of Justification" in FIG. 11). This condition is satisfied preferred range is approximately "x / t PL is a range satisfying the ≧ -0.2 × α + 5".
Further, bending angle α lap regardless of the value steel position x / t PL is less than 1.8 (x / t PL is smaller and <1.8), described in the above-described reference (L1 ≧ 2 × t that PL that was unable to satisfy the criteria of)
[0079]
Even when welding is performed in one pass, if production of lap fillet weld joint in condition that the value of the area inside the polygon shown in FIG. 11, , , , , and , and the root portion 550, preferred for 560 welding failure due to expansion of the gap g does not occur.
From the above, assuming that the welding in a single pass, bending angle alpha in the range of 35 ° or less 10 ° or more (i.e., 10 ° ≦ alpha ≦ 35 °), and overlaid the upper limit of the junction length L1 thickness t of the steel sheet 420 PL to four times the sheet thickness t of the steel sheet 420 overlapping the upper limit of the gap g of the root portion 550, 560 PL is preferably set to.
[0080]

In the present embodiment, it is an object to reduce the stress concentration of lap fillet arc welded joint. Thus, the type of steel sheet is not particularly limited. For example, the tensile strength tensile strength of mild steel plate of about 270MPa is that it is possible to use various tensile strength of the steel sheet up to ultrahigh-tensile steel plate of about 1180 MPa. However, high-tensile steel plate in terms of weight of the member (e.g., tensile strength steel sheet more than 590MPa as measured by the method described in JISG3101) preferably used. Also, even a combination of steel of the same type may be combined with steel heterogeneous.
[0081]
In addition, there is no special restriction with regard plate thickness of the steel plate. However, in view of suppressing the deformation of the member by bending moment when a load is applied to the member, bending to one or both of the steel plate 410 and stacked steel plate 420, the following thin steel plate thickness of 1.6mm or more 3.4mm it is effective to use. Further, even if the plate thickness using the same steel sheet, may be used steel plate thickness is different.
[0082]
From the viewpoint of corrosion resistance of the member, galvanized steel (steel zinc plated surface) may be used. However, in a typical lap fillet arc welded joint, blowholes tend to occur due to zinc vapor in the root portion, which can be a problem. The lap fillet arc welded joint according to the present embodiment, the route section 550 and 560 is either a gap, the contact at a plurality of points depending on the state of the machining of the contact with the line (one end face of the stacked steel plates 420 (front end surface) ) becomes one of the states of either. Therefore, zinc vapor during welding, without entering into the molten metal, is easy to be discharged from between the steel plate 410 and stacked steel sheets 420 bent at the root portions 550 and 560 side. Therefore, it is possible to suppress the blowholes.
Thus, one or both of the bent steel plate 410 and stacked steel sheets 420, it is effective corrosion resistance can be obtained when using a galvanized steel sheet. Incidentally, the zinc plating, so long as it contains zinc plating, for example, galvanized steel sheet or galvannealed steel sheet and the like are included in the galvanized steel sheet. Further, a steel sheet plated than zinc-plated surface may be used for one or both of the bent steel plate 410 and stacked steel plate 420.
[0083]

Next, an example of a manufacturing method of lap fillet arc welded joint.
First, a two planar steel. Next, of the two steel plates, bending the one end side of the region of one of the steel sheet. The bending angle alpha, designers determined based on the load or the like is assumed to participate in shape and members of the members. When producing a lap fillet arc welded joint in a single pass, the bending angle α is set to be in the range of 10 ° or more than 35 °. When producing meat arc welded joint corner lap in multiple passes, bent to an angle α may be in the range of 10 ° or more than 35 °, or not. However, from the viewpoint of workability of the machining, bending the angle α preferably more than 10 °. Thus the production of bent steel plate 410. Among the two steel plates, the other steel plate becomes superimposed steel plates 420.
[0084]
Next, the positioning of the steel plate 420 overlapping the bent steel plate 410. During this positioning, the plate surface area 410b of the bent steel plate 410, so that the plate surface of the stacked steel plates 420 substantially parallel.
Further, the shift amount of the thickness center axis of the bent steel plate 410 and stacked steel plate 420 in the thickness direction (Z axis direction), folded thickness T of the steel sheet 410 PB thickness T of the superimposed steel plates 420 PL of the mean value of the and 1/2 times or less.
[0085]
Further, the X in the axial position of the tip of the folded and has regions 410a of the steel sheet 410 folded, and either the X-axis direction position of the region 420a of the overlapping steel plates 420 overlap each other, and the area of ​​the overlapping steel plate 420 in 420a, so that the position in the Z-axis direction of at least a partial region of the overlapping steel plate 420, and either the position of the Z-axis direction of a region 410a of the bent steel plate 410 overlap one another, the steel plate bent (before welding) 410 and the region 410a of the one end of the (pre-welding) superimposed steel plates 420, so as to face each other in a state of having a contact with each or intervals.
[0086]
The distance between the region 410a of the (pre-welding) bent steel plate 410, and one end of the (pre-welded) overlaid steel plates 420, the thickness t of the steel sheet superimposed weld length L1 PL more than double the It is defined as. Weld length L1, based shape or members, and the load that is assumed to join the members, the bending steel sheet 410 and the shape and size of the overlapping steel plate 420 (the length of the bending angle α and bent to have a region, etc.), etc. designer Te decide.
[0087]
The present inventors have also changed welding conditions such as the thickness of the welding method and a steel sheet, bending angle α and overlaid steel plates located x / t PL is superimposed under the condition that the value of the area within the polygon shown in FIG. 11 if production of fillet weld joints, one-pass welding, the above-described , , , and .
[0088]
When performing welding in one pass, upon the positioning of the steel plate 420 overlapping the bent steel plate 410, "≦ x 1.8 / t PL ≦ 5", "x / t PL ≦ -0.125 × alpha + 6. 875 ", and" x / t PL preferably further satisfies ≧ -0.2 × α + 5 "condition.
[0089]
On the other hand, when performing welding in multiple passes, when positioning the steel plate 420 overlapping the bent steel plate 410, necessarily, "1.8 ≦ x / t of the PL ≦ 5", "x / t PL ≦ - 0.125 × α + 6.875 ", and" X / T PL conditions it is not necessary to satisfy the ≧ -0.2 × α + 5 ". However, even when performing welding in multiple passes, in the same way as the case of performing the welding in a single pass, it may be carried out positioning of the steel plate 420 overlapping the bent steel plate 410.
Positioning is performed in the manner described above, the folding steel 410 and overlaid steel plates 420, fixed using a jig or the like.
[0090]
Then, folding the regions 410a that are bent of steel sheet 410, with respect to each other to a region opposed to the one end of the lap steel 420, the positive direction side of the Z axis (bending the folded and has regions 410a of the steel plate 410 superposed from the front end steel plate 420 supplies a direction from) the welding wire visible on the front side, performs meat arc welding corner overlapped along the Y-axis direction (sheet width direction of the bent steel plate 410 and stacked steel plate 420).
[0091]
Type of welding wire is not particularly limited, may become under-matching even if the over-matching, but by the over-matching, higher weld fatigue strength can be expected.
[0092]
Further, in the present embodiment, the gas-shielded arc welding. At that time, in the present embodiment, as the shield gas, argon gas which is an example of an inert gas (Ar gas), carbon dioxide (CO 2 gas) or oxygen gas (O 2 mixed gas containing a gas) used.
Carbon dioxide gas for shielding gas (CO 2 volume fraction of gas), for example, can be 20 vol% or less 3% by volume or more. Further, the oxygen gas to the shielding gas (O 2 volume fraction of gas), for example, be a 4 vol% or more 1% by volume.
[0093]
As described above, bending the weld toe 530 of the steel plate 410, preferably is located on the surface of the region not inclined folding steel 410. For this purpose, it is preferable to increase the width of the weld bead can be in a single weld. From this point of view, to facilitate expanding the plasma generated by the arc discharge, so as to be able to increase the width of the weld bead can be in a single welding, carbon dioxide gas (CO 2 gas), oxygen gas (O 2 gas preferably, reduce the amount of). Thus, carbon dioxide gas to the shielding gas (CO 2 volume fraction of gas), for example, is preferably to 3 vol% to 10 vol% or less, and the oxygen gas to the shielding gas (O 2 volume fraction of gas), for example, preferably below 1 vol% or more 3% by volume. Further, in order to prevent the welding phenomenon may become unstable, carbon dioxide gas to the shielding gas (CO 2 volume fraction of gas), for example, it is preferably set to 10 vol% 5 vol% or more or less, the shield gas the oxygen gas to the (O 2 volume ratio of the gas), for example, is to below 2 vol% to 3 vol% and more preferably.
Meat arc welded joint corner superimposed as described above is manufactured.
[0094]
Here, it has been described by taking the case of providing 2 sheets of steel as an example. However, the steel sheet bending one end of one of the steel sheet as the steel sheet overlaid other end, may be prepared lap fillet arc welded joint.
[0095]
　The lap fillet arc welded joint according to the present embodiment as described above, the thickness t of the steel sheet 420 overlapping weld length L1 PL be twice or more. Further, the shift amount of the thickness center axis 510, 520 of the bent steel plate 410 and stacked steel sheets 420, the thickness t of the bent steel plate 410 PB thickness t of the overlapping steel plate 420 PL is 1/2 times or less the average value of . Also, bending the position of the Z-axis direction of the weld toe 530 of the steel plate 410, bent at a position on the plate surface of the inclined non region of the steel sheet 410, the plate surface on the side where the weld bead 430 is formed from position, in the range of up to a position inclined to have no region of the thickness center axis 510 of the bent steel plate 410.
[0096]
By configuring in this way overlapping fillet arc welded joint, even in a state in which a gap between the steel plates, meat arc welded joint corner stress superimposed concentration is small weld toe 530, 540 and root portion 550 and 560 it is possible to provide.
In particular, it is possible to reduce the stress concentration of a typical overlapping corners root portion 560 of the overlapped steel sheets 420 a large stress concentration occurs in meat arc welded joint. Therefore, it is possible to improve the fatigue strength of the welded members, for example, can be produced underbody member of a motor vehicle by performing a lap fillet arc welding to high strength steel sheets. This makes it possible to reduce the weight of the vehicle body.
[0097]
Further, the overlapped fillet arc welded joint according to the present embodiment, the bending angle α as 35 ° or less 10 ° or more, the thickness t of the gap g is superimposed steel plates 420 route section 550, 560 PL is less, the junction length L1 is the thickness t of the overlapping steel plate PL and less than four times. Such overlapping corner in making the weld joint, lap steel position (x / t PL and be a) a range of 1.8 to 5, and "x / t PL ≦ -0.125 × alpha + 6. 875 "and" X / T PL so as to satisfy the conditions of ≧ -0.2 × α + 5 ". I this way, it is possible to perform welding in one pass, it is possible to reduce the welding times (number of passes).
In the present embodiment it has been described as an example where the metal plate is a steel sheet, the above-mentioned conditions, since the same even in the case of using a metal plate other than a steel sheet, a metal plate is not limited to steel .
[0098]
Lap fillet arc welded joint according to another embodiment of the present invention comprises a first metal plate, a second metal plate, and the first metal plate and the junction of the second metal plate welded a lap fillet arc welding joint has a bead, one end region of the first metal plate is bent, the first tip of the first of said folded and has a region of the metal plate position of the direction, overlaps with any of the position of the first direction of said one end region of the second metal plate, said first direction, the direction and the second along the weld line of the weld bead a direction perpendicular to the thickness direction of the second metal plate, wherein one end side of the region of the second metal plate, the position of the second direction of said at least a partial area of ​​the second metal plate, said overlap with any of the position of the second direction of the folded and has a region of the first metal plate , The second direction is the a plate thickness direction of the second metal plate, wherein one end side area of ​​the second metal plate, a region following the bent and has a region of said first metal plate and is substantially parallel to, the weld bead, the second metal plate, in the area including the region between the first of said folded and has a region of the metal plate, wherein the first metal and the center of the second direction of the bent following the region are regions of the plate, with the center of the second direction of said one end region of the second metal plate, the deviation in the second direction the amount, the first no more than half of the metal plate and the second mean value of the thickness of the metal plate, in a cross section of the lap fillet arc welded joint, joint length, the second not less than 2 times the plate thickness of the metal plate, the cross section of the lap fillet arc welded joint, said first direction Preliminary a second cross section taken along the direction of, the joint length is the length from the root portion of the second metal plate to the weld toe of the first metal plate, said position of the second direction of the weld toe end of the first metal plate is in the range from the first position to the second position, said first position, said first metal plate a position on the plate surface of the area following the bent region is a position on the plate surface on the side where the weld bead is formed, the second position, the said first metal plate characterized in that it is a position of the center in the second direction in the region following the bent region.
[0099]
(Example)
Next, an embodiment of lap fillet arc welded joint according to the present invention.
As the steel plate, and 980MPa grade galvanized steel plate thickness is 1.8 mm, the plate thickness was used 590MPa grade non-plated steel plate of 3.2 mm.
[0100]
When the plate thickness to produce a lap fillet arc welded joint with 980MPa grade galvanized steel sheet 1.8mm was used 780MPa grade welding wire as the welding wire. When the plate thickness to produce a lap fillet arc welded joint with 590MPa grade non-plated steel plate of 3.2mm was used 490MPa grade welding wire or 780MPa grade welding wire as the welding wire.
[0101]
As shielding gas, Ar gas to CO 2 gas of 3 vol% to 20 vol% mixed gas mixture was allowed or Ar gas to the O, 2 with gas 1 vol% to 2 vol% mixed gas mixture was allowed.
[0102]
Welding method as Parusumagu welding, for steel plate thickness 1.8 mm, was welded to the welding current 180A, the welding voltage 22V, a welding speed as 0.6 ~ 1.0m / min. Further, with respect to the steel plate thickness is 3.2 mm, the welding current 250A, the welding voltage 27V, and the welding speed as a 0.5 ~ 1.0m / min. By varying the welding speed as much as possible, while preventing the burn through during welding and by changing the weld bead width to produce a different welding test piece of toe position.
[0103]
By performing a single pass or two-pass the Parusumagu welding under the above conditions, to produce a meat arc welded joint corner lap corner common overlapping and meat arc welded joints with bent steel plate. As described above, the overlapped fillet arc welded joints with bent steel sheet, folding the end portion of one of the steel plate of the two steel plates are produced by overlapping fillet arc welding two steel plates is superimposed fillet arc welded joints that. That is overlapped fillet arc welded joint described in the above embodiments. On the other hand, typical lap fillet arc welded joint is a lap fillet arc welded joint is produced by performing the plate surface together without bending the ends are opposed overlapped fillet arc welding of the steel sheet.
[0104]
The folding lap fillet arc welded joints using the steel sheet, bending angle α and the overlap steel position x, and the amount of deviation between the thickness center axis of the plate thickness center axis and overlapped steel bending steel sheet, folding the root of the steel sheet the gap g between the root portion of the parts and superimposed steel plates manufactured different.
For general lap fillet arc welded joint, the amount of deviation of the thickness center axis of the two steel plates (displacement amount in the Z-axis direction of the thickness center axis of the two steel plates) were prepared and different. Also, for general lap fillet arc welded joint, which steel sheets are in contact at its end portion and (that there is no gap) was prepared as a gap between the plate surface of the steel sheet.
[0105]
For each meat corners piled with folded steel arc welded joint and common overlapping fillet arc welded joints were evaluated weldability. Occurrence of blowholes, flows of the weld metal, or perforated in the weld metal occur, appearance, for which the welding is not properly performed, and the weldability as "bad". On the other hand, the appearance, for which the welding is appropriately performed, and the weldability as "good".
[0106]
For each weldability is overlapped fillet arc welded joint of "good", performs an axial force fatigue test stress ratio 0.1 in accordance with JISZ2273, surveys the position where the load can crack occurs more than fatigue limit strength and fatigue limit did.
The divided by the cross sectional area of the steel sheet overlaid test load and the test stress, the number of repetitions of applied load of 200 million times, was considered a stress range not occur cracks in the welded portion and the fatigue limit. In the following, it may be referred to as the fatigue limit and fatigue strength. It should be noted that weldability is for the welded joints of the "bad" is not subjected to such an investigation.
[0107]
Determination of fatigue strength, on the basis of the fatigue strength in the experimental example No. 1 of Table 1 below, the fatigue strength in the experimental example of the improvement rate (the number for the fatigue strength of each example, the number 1 the determination of when divided by the fatigue strength in the experimental example) is more than twice as "pass", and the otherwise set to "fail".
[0108]
Also, regarding the built-arc welded joint corners piled with folded steel plates were Locate the weld toe of the bent steel plate. Weld toe of the bent steel sheet, was evaluated as "excellent" when present on the surface of the region not inclined bending steel sheet. Position of the weld toe of the bent steel sheet in the Z axis direction, and when the position of the tip end of the bent steel sheet than the position of the folding plate thickness central axis inclined non region of the steel sheet as "bad".
Folding weld toe of the steel sheet, the position of the weld toe of the bent steel sheet in no case (Z-axis direction at any position of the can, folded position of the inclined non region surface of the steel sheet, bending of the steel plate when in the position between the position of the thickness center axis in the region not tilted) was evaluated as "good".
[0109]
The results are shown in Table 1 ~ Table 3]. Incidentally, in the column of "steel" in Table 1] - [Table 3], "590" indicates that the plate thickness using two sheets of 590MPa grade non-plated steel plate of 3.2 mm, "980" is indicates that "plate thickness using two sheets of 980MPa grade galvanized steel sheet 1.8 mm.
[0110]
In the column of "welding wire", "780" indicates the 780MPa class welding wire, "490" indicates the 490MPa class welding wire.
In the column of "shielding gas", "Ar + 20% CO 2 " is, CO in Ar gas 2 gas show a mixed gas obtained by mixing 20 vol%, "Ar + 5% CO 2 " is, CO in Ar gas 2 gas 5 indicates a mixed gas obtained by mixing vol%, "Ar + 3% CO 2 " is, CO in Ar gas 2 shows a mixed gas obtained by mixing gas 3% by volume. "Ar + 2% O 2 " are, O in Ar gas 2 shows a mixed gas of the gas is mixed 2 vol%, "Ar + 1% O 2 " are, O in Ar gas 2 a mixed gas of the gas obtained by mixing 1 vol% show.
[0111]
"Bending angle", shows the bending angle α of the bent steel plate.
[0112]
In the column of "thickness deviation of the center", for experimental example of the numbers 4-28 (Table 2 and Table 3), the deviation of the thickness center axis of the plate thickness center axis and overlapped steel bending steel It indicates the amount, for example experiment numbered 1-3 (Table 1) shows a displacement amount of the thickness center axis of the two steel plates.
"+" Is bent with respect to the thickness center axis of the inclined non region of the steel sheet, one end region of the overlapping steel plate thickness center axis, the side weld toe is formed (the Z-axis positive indicating that the image is shifted direction). "-" is bent with respect to the thickness center axis of the inclined non region of the steel sheet, thickness center axis of the one end region of the overlapping steel plate, the negative direction side of the side (Z-axis root portion is formed ) to indicate that it is displaced.
[0113]
In Table 1] - [Table 3], these shift amount is (plate thickness t of the bent steel sheet average thickness t PB thickness t of the overlapping steel plate PL expressed in multiples to the average thickness of the) ing.
[0114]
The column of "x-position" indicates a lap steel position x. In the column of "g" indicates a gap between the root portion of the root portion and the overlapping steel plate of the steel plate bent in the thickness direction of the stacked steel plates. In the column of "L1" indicates a weld length.
In the column of "toe portion position" indicates the position of the weld toe of the bent steel sheet, in Table 1 ~ Table 3, "Yu" earlier its position, "good", "bad It is shown in ". In addition, in the column of "crack position", indicating the position at which fatigue crack was the first to occur. "Route" means that the fatigue crack occurs from the root portion, "toe" means that the fatigue crack from weld toe occurs.
[0115]
In the column of "improvement rate for a conventional" indicates the fatigue strength relative to the fatigue strength of the experimental example No. 1 (fatigue strength fatigue strength ÷ number 1 of each number). "Determination" indicates the criteria for fatigue strength as described above.
[0116]
[Table 1]

[0117]
[Table 2]

[0118]
[table 3]

[0119]
First, description will be given general lap fillet arc welded joint. [Table 1] is an experimental example of No. 1-3 general overlapped fillet arc welded joint, in which both were produced by performing the one-pass welding. However, as described below, in the experimental example No. 2, welding becomes poor in 1-pass welding, it could not produce a weld joint that will contribute to the determination of the fatigue strength.
[0120]
As shown in No. 1 of Table 1, the fatigue strength in the case of general lap fillet welding with a non-plated steel sheet 590MPa grade was 70 MPa. On the other hand, as shown in No. 2, in galvanized steel sheet 980MPa grade, a shift amount of the thickness center axis of the two steel plates Doing common overlapping fillet arc welding in the 1t, the two steel plates since there is no gap, blow holes are generated by zinc vapor was the welding defect.
[0121]
Therefore, as shown in No. 3, providing a 0.5mm gap between the two steel plates, but can not prevent the blowholes, the amount of deviation of the thickness center axis of the two steel plates is 2.3 mm ( = 1t + 0.5 mm), and the fatigue strength was lower than in experimental example No. 1. For this reason, became a "fail" in the determination conditions described above. That is, in the experimental example No. 3, despite using 980MPa grade steel showed lower fatigue strength than lap number 1 fillet joints using the 590MPa grade steel.
[0122]
Therefore, in this embodiment, as described above, in any of the non-plated steel plate and 980MPa grade galvanized steel sheet 590MPa grade, determination of the fatigue strength, relative to the fatigue strength in the experimental example No. 1 (Table see column "improvement rate for a conventional" in 1] - [Table 3]).
[0123]
Next, it overlapped corner for meat arc welded joint will be described using the folded steel plate. [Table 2] and a superposed corner experimental example meat arc welded joint with the bent steel sheet Nos. 4 to 28 of Table 3. In the experimental example No. 4 ~ 18, 22 ~ 28 performs one-pass welding, the experimental example No. 19-21 were two-pass welding. However, as described below, welding becomes poor in one pass welding in Experiment numbers 24 and 25, could not produce a weld joint that will contribute to the determination of the fatigue strength.
[0124]
As shown in No. 22, when the amount of deviation between the thickness center axis of the plate thickness center axis and overlapped steel bending steel sheet + 0.8 t (80% of the average thickness t) and large, the corner common overlapping although fatigue strength than the wall arc welded joint is higher, it becomes "fail" in the determination condition of fatigue strength as described above.
As shown in No. 23, the bending angle α is large, if the overlapping steel plate position x is relatively small, the thickness t of the steel sheet superimposed weld length L1 PL is less than 2 times the determination condition of fatigue strength as described above became a "fail" in.
[0125]
As shown in No. 24 and 25, bending angle α but is appropriate, when superimposed steel position x is large, the gap g between the root portion of the root portion and the overlapping steel plate bent steel sheet, the thickness of the overlapping steel plate t PL to become large as 1.3 times or more, a pinhole defect occurs in the weld toe of overlapped steel sheets became welding failure in one pass welding.
[0126]
Further, as shown in No. 26 and 27, if bending angle α is small, a large overlapping steel plate position x, weld toe of the bent steel sheet, positioned at the front end side of the region which is bent the bent steel plate.
In the experimental example No. 26, below the weld toe of the bent steel plate bending thickness center axis inclined non region of the steel plate (weld toe 530 of FIG. 5) (thickness center axis 510 of FIG. 5) It was a side (distal end side of the bent of folded steel plate area). Therefore, it is the position of the weld toe of the bent steel sheet poor, becomes fractured from low toe portion fatigue strength, becomes "fail" in the criteria for fatigue strength as described above.
[0127]
Also, number 27, CO in Ar gas 2 is an experimental example in which a mixed gas obtained by mixing gas 5 vol% as shielding gas, although the weld length L1 increases, weld toe of the bent steel plate thickness center axis of the area is not inclined folding steel (weld toe 530 of FIG. 5) from the lower side (thickness center axis 510 of FIG. 5) (the distal end side of the bent of folded steel plate area) because became, the position of the weld toe of the bent steel plate becomes defective. For this reason, the criterion of fatigue strength was a "fail".
[0128]
As shown in No. 28, when the amount of deviation between the thickness center axis of the plate thickness center axis and overlapped steel bending steel sheet is as large as -0.7t (70% of the average thickness t) are common overlapping although corner fatigue strength than the wall arc welded joint is higher, it becomes "fail" in the determination condition of fatigue strength as described above.
[0129]
On the other hand, as shown in No. 4-18, in the lap fillet arc welded joint according to the present invention, weldability was a "pass" in the "good", and determination condition fatigue strength described above. Further, as shown in No. 4-18, in the lap fillet arc welded joint according to the present invention, weldable and fatigue strength, thickness, type of the steel sheet, it can be seen that does not depend on the welding wire.
[0130]
For Experiment number 19-21 has been difficult construction in one-pass welding, FIG. 13 (a), the but is obtained by construction with two-pass welding shown in FIG. 13 (b), both , , and , criteria for fatigue strength as described above was passed.
In the experimental example No. 19, 21, as shown in FIG. 13 (a), to form a weld bead 430a in the first welding, to form a weld bead 430b at the second welding, the weld bead 430 did. In the experimental example No. 20, as shown in FIG. 13 (b), to form a weld bead 430a in the first welding, to form a weld bead 430b at the second welding, and the weld bead 430.
[0131]
The embodiments of the present invention described above are all merely illustrate concrete examples of implementing the present invention, the technical scope of the present invention should not be restrictively interpreted it is intended. That is, the present invention without departing from its spirit or essential characteristics thereof, can be implemented in various forms.
[0132]
Terms described above may be in a correspondence relationship as follows.
"The first metal plate" corresponds to, for example, bending a steel sheet 410.
"Second metal plate" corresponds to, for example, the superimposed steel plates 420.
"First direction" corresponds to, for example, the X-axis direction.
"Second direction", for example, corresponds to the Z-axis direction.
"Said the center of the second direction of the first of said bent following the region is a region of the metal plate, with the center of the second direction one end side area of the second metal plate, wherein shift amount in the second direction ", for example, corresponds to the amount of deviation between the thickness center axis of the plate thickness center axis and overlapping steel plate 420 of the bent steel plate 410.
"Section of the lap fillet arc welded joints", for example, correspond to the X-Z cross section of lap fillet arc welded joint (see FIG. 5, etc.).
Industrial Applicability
[0133]
Lap fillet arc welded joint according to the present invention is suitably used for performing lap fillet welding, even in a state in which a gap between metal plates, the stress concentration of the weld toe and root portion can be a small overlap fillet arc welded joint. Accordingly, the present invention has a high industrial applicability.
DESCRIPTION OF SYMBOLS
[0134]
400: member
410: bent steel plate
410a: folded regions are bent with one end of the steel plate
410b: folded following the area which has been bent the steel sheet region
420: Superimposing steel
420a: one end of the region of the overlapping steel plates
430 and 440: weld bead
510: bent steel sheet having a thickness of the central axis
520: superimposing steel sheet having a thickness of the central axis
530: bent steel plate weld toe
540: welding of overlapping steel toe portion
550: folded steel root portion
560: lap steel root section

The scope of the claims
[Requested item 1]
A first metal plate, a second metal plate, a lap fillet arc welded joint and a weld bead to be the first metal plate and the junction of the second metal plate,
said first of which region of one end side is bent metal plate,
the weld bead is located in a region including the second metal plate, the region between the said folded and has a region of the first metal plate ,
in a cross-sectional view of a cross-section perpendicular to the weld line of the weld bead,
in a first direction, the position of the tip of the bent and has a region of said first metal plate at one end of said second metal plate region and overlap
　in the second direction, the deviation amount between the center axis of the first of said one end region of the centering axis of the bent following the area region of the metal plate a second metal plate but half of the first metal plate and the average value of the thickness of the second metal plate A bottom,
said first direction, said a plate thickness direction perpendicular to the direction of the weld line along the direction and the second metal plate of the weld bead, the second direction is the second metal a plate thickness direction of the plate,
the length of the junction length from the root portion of the second metal plate to the weld toe of the first metal plate of the plate thickness of the second metal plate 2 and at more than double
the range from the first position of the weld toe of the metal plate is first position in the second direction to a second position,
said first position, said first a position on the plate surface of the area following the bent and has a region of first metal plate, a position on the plate surface on the side where the weld bead is formed,
the second position, the of the region following the bent and has a region of the first metal plate, the position der of the central axis in the second direction
Lap fillet arc welded joint, characterized in that.
[Requested item 2]
In a cross-sectional view of a cross-section perpendicular to the weld line of the weld bead,
said the first of said folded and has a region of the metal plate, the angle at which the bending angle of the plate surface of the second metal plate is 10 ° above 35 ° or less,
the joint has a length less than 4 times 2 times the thickness of the second metal plate,
said first of said root of said second metal plate and the root portion of the metal plate Department and the distance in the second direction is less than the thickness of said second metal plate
piled fillet arc welded joint according to claim 1, characterized in that.
[Requested item 3]
Representative value of the joint length is not less than twice the thickness of the second metal plate,
the representative value of the joint length, the joint length of the plurality of the cross section of the lap fillet arc welded joints determined based on the
overlapped fillet arc welded joint according to claim 1 or 2, characterized in that.
[Requested item 4]
Thickness of the second metal plate and the first metal plate is 1.6mm or more 3.4mm or less
overlapped fillet arc welding according to any one of claims 1 to 3, wherein the joint.
[Requested item 5]
Wherein the first metal plate a second metal plate is galvanized steel sheet
overlaid fillet arc welded joint according to any one of claims 1 to 4, wherein the.