Art
[1][Correction of 13.08.2018 under Rule 26]　
The present invention relates to a method of manufacturing and coating adhesion with the steel sheet for hot press forming after coating member having excellent corrosion resistance.
[2]
BACKGROUND
[3]
Recently, due to the high interest in the environment and the depletion of oil energy regulations on fuel efficiency of cars it is becoming increasingly powerful.
[4]
[5]
It is to reduce the thickness of the steel sheet is used as one method for improving the fuel economy of the vehicle. However, this may cause problems to the vehicle's safety when reducing the thickness, not necessarily improving the strength of the steel plate is supported on the material side It should be.
[6]
[7]
Such was the demand for high-strength steel continues to occur reason, there are various types of steel bars developed. However, these steel sheets have a problem that workability is poor because it has a high strength in itself. That it is, because it has a rating of the steel sheet strength and elongation multiplication always tends to take up a certain value, when the higher the strength of the steel sheet had a problem in that it reduces the elongation which is an index of workability.
[8]
[9]
There have been proposed for hot press molding method to solve these problems. Hot press molding is then processed into a good high temperature to process the steel sheet to form a cold tissue such as the martensite in the steel sheet by quenching it to a lower temperature, a method of increasing the strength of the final product. In this case also, as has the advantage of being able to minimize the problem of workability when producing a member having a high strength.
[10]
[11]
However, if in the hot press forming method has become a steel sheet surface oxide because the steel must be heated to a high temperature thus there is a problem that should be added to the process of removing an oxide on the surface of the steel sheet after the press forming.
[12]
[13]
As a way to solve this problem, the invention US Patent No. 6,296,805 call has been proposed. The invention is used in the process of heating and quenching the steel plate subjected to aluminum plating after hot press forming or molding temperature (briefly "after heat treatment"). The aluminum coating layer is not the steel sheet at the time of thermal oxidation due to the presence on the surface of the steel sheet.
[14]
[15]
However, even if the aluminum plating layer on the surface to do this steel sheet is not oxidized during heating member obtained after the heating and molding are still exposed to the corrosive environment. In particular, the possession of iron diffusion in the process of heating the coated steel sheet, aluminum plated layer on the surface of the steel sheet are formed a Fe-Al-based plated layer of a hard, in the case of Fe-Al-based plated layer has a crack caused in the coating layer due to weak as hard there is a possibility there is a possibility that the carrying steel plate exposed to a corrosive environment accordingly.
[16]
[17]
In order to prevent such that there be a seal layer forming hot press forming member, where it is required to have excellent coating adhesion.
[18]
Detailed Description of the Invention
SUMMARY
[19]
According to one aspect of the present invention has excellent coating adhesion and corrosion resistance, with the result that the excellent hot press steel sheet for hot press forming to produce a molded part is provided after the coating.
[20]
[21]
An object of the present invention is not limited to the above-described information. Those having ordinary skill in the art will not have any difficulty in solving an additional object of the present invention from a comprehensive overview of the invention herein.
[22]
Problem solving means
[23]
Steel sheet for hot press forming according to one aspect of the present invention possessing the steel sheet and a plating layer formed on a surface of the carrying plate, the area ratio of the void in the cross-section of the surface layer is observed by cutting the plated layer in the thickness direction, the entire surface layer a may be equal to or greater than 10% compared to area.
[24]
[25]
In one implementation example of the invention, the area ratio of the void in the cross-section of the surface layer is observed by cutting the plated layer in the thickness direction be equal to or greater than 15% compared to the area of ​​the entire surface layer.
[26]
[27]
In one implementation example of the invention, the coating layer may be an aluminum alloy plate layer.
[28]
[29]
In one implementation example of the invention, the aluminum alloy plate layer has a mean content of Fe of 30% by weight or more.
[30]
[31]
In one implementation example of the invention, the aluminum alloy plate layer has a mean content of Fe be at least 40% by weight.
[32]
[33]
In one implementation example of the present invention, the possession of the steel sheet in weight% C: 0.04 ~ 0.5%, Si: 0.01 ~ 2%, Mn: 0.01 ~ 10%, Al: 0.001 ~ 1.0%, P: 0.05% or less, S : not more than 0.02%, N: not more than 0.02%, the remainder may have a composition including Fe and other inevitable impurities.
[34]
[35]
In one implementation example of the invention, the composition of the possession of the steel sheet in weight%, Cr, the sum more than one member selected from the group consisting of Mo and W: 0.01 ~ 4.0%, Ti, Nb, from the group consisting of Zr and V 1 the sum of two or more: 0.001 ~ 0.4%, Cu + Ni: may further include one or more from among 0.0001 ~ 0.01%: 0.005 ~ 2.0%, Sb + Sn: 0.001 ~ 1.0%, and B.
[36]
[37]
Method of manufacturing a steel sheet for hot press forming member according to one aspect of the present invention is to obtain a carrying surface of the steel sheet to the aluminum plating and aluminum-coated steel sheet by taking volume; Step aluminum alloy plated steel sheet by annealing aluminum plated steel sheet; And a method for manufacturing a steel sheet for hot press forming member comprises the step of cooling the aluminum alloy-plated steel sheet, the aluminum coating weight is 30 ~ 200g / m to one side of the steel plate based on 2 a, and the winding tension during the winding 0.5 ~ 5kg / mm 2 with, and the annealing is carried out at a heating temperature range of 550 ~ 750 ℃ 30 bun ~ 50 hours at a appeal placed, when heated in room temperature during the annealing to the heating temperature, the average temperature increase rate 20 ~ 100 ℃ / h, but as a, a 400 ~ 500 ℃ average temperature rise rate of 1 ~ 15 ℃ / h of the interval, and the rate of temperature increase of the heating temperature of the heating temperature range -50 ℃ ~ to 1 ~ 15 ℃ / h, based the furnace appeal and the difference between the ambient temperature and the steel plate temperature at 5 ~ 80 ℃, can be cooled at a rate of 50 ℃ / h or less in the step of cooling the aluminum alloy-plated steel sheet to 500 ℃.
[38]
[39]
In one implementation example of the present invention, the possession of the steel sheet in weight% C: 0.04 ~ 0.5%, Si: 0.01 ~ 2%, Mn: 0.01 ~ 10%, Al: 0.001 ~ 1.0%, P: 0.05% or less, S : not more than 0.02%, N: not more than 0.02%, the remainder may have a composition including Fe and other inevitable impurities.
[40]
[41]
In one implementation example of the invention, the composition of the possession of the steel sheet in weight%, Cr, the sum more than one member selected from the group consisting of Mo and W: 0.01 ~ 4.0%, Ti, Nb, from the group consisting of Zr and V 1 the sum of two or more: 0.001 ~ 0.4%, Cu + Ni: may further include one or more from among 0.0001 ~ 0.01%: 0.005 ~ 2.0%, Sb + Sn: 0.001 ~ 1.0%, and B.
[42]
Effects of the Invention
[43]
According to one aspect of the invention, hot because of the press it includes a cavity is for forming the steel sheet surface layer, and the surface roughness of the member obtained after hot press forming may have a significantly high and good adhesion with paint, so that after a good paint corrosion resistance It can be obtained.
[44]
Brief Description of the Drawings
[45]
1 is a cross-sectional photograph observing the plated layer of a cut surface of the steel sheet according to one implementation example of the invention.
[46]
Figure 2 is a profile component analysis of the plating layer of the steel sheet produced according to Examples 1 to GDS analyzer.
[47]
Figure 3 is a scanning electron micrographs (back scattered electron images) of observing the cross section of the plating layer of the steel sheet produced according to Examples 1.
[48]
4 is a profile component analysis of the plating layer of the steel sheet produced according to Inventive Example 2 in GDS analyzer.
[49]
Figure 5 is a scanning electron micrographs (back scattered electron images) of observing the cross section of the plating layer of the steel sheet produced according to Inventive Example 2.
[50]
6 is a profile component analysis of the plating layer of the steel sheet produced according to Comparative Example 1 in GDS analyzer.
[51]
Figure 7 is a scanning electron micrograph of observing the cross section of the plating layer of the steel sheet produced according to Comparative Example 1.
[52]
8 is a profile component analysis of the plating layer of the steel sheet produced according to Comparative Example 2 in GDS analyzer.
[53]
Figure 9 is a scanning electron microscope observing the plated layer of the cross-section of the steel sheet produced according to Comparative Example 2.
[54]
10 is a profile component analysis of the plating layer of the steel sheet produced according to Comparative Example 3 in GDS analyzer.
[55]
Figure 11 is a scanning electron microscope observing the plated layer of the cross-section of the steel sheet produced according to Comparative Example 3.
[56]
Best Mode for Carrying Out the Invention
[57]
Hereinafter, the present invention will be described in detail.
[58]
[59]
La member in the present invention means a material for the part or parts produced by hot press forming. In addition, the steel sheets there is a case means that prior to hot press forming, and such a steel sheet having a coil form is wound during the production process this time is also referred to as a coil.
[60]
[61]
1 is a cross-sectional photograph observing the plated layer of a cut surface of the steel sheet according to one implementation example of the invention. It is seen in the figure, as the steel sheet of the present invention is composed of the plating layer formed on the surface of the substrate plate and carrying plate and has a plurality of voids (pore) in the surface layer part of the plated layer. This is a can not be observed phenomenon in the conventional hot press forming the aluminum-coated steel sheet for molding, while in the conventional aluminum-plated steel sheet a void in the surface layer by the molten aluminum plating does not substantially occur, the surface layer portion of the steel sheet according to the present implementation cases of the coating layer it is characterized mainly in that a plurality of voids is formed. Is referred to as a surface layer in this case is implemented within a region of 10㎛ depth from the surface (when the surface roughness is to measure the depth from the respective points of the rough surface).
[62]
[63]
If included in a large number of pores in the surface layer plated layer of the steel sheet, there is a steel sheet when heating the hot molding press, to be partially open in by the stress applied during pressing gap the surface layer, which serves to increase the roughness of the surface of the plating layer and the.
[64]
[65]
Hot press forming member for an aluminum-plated steel sheet obtained by hot press molding the alloy is produced to the surface. As a result, the alloy layer is obtained by comparison with non-alloyed Al plating layer is relatively stable is room for improving the adhesion with paint only conventional phosphating phosphate and reactive performed in order to improve the coating adhesion is weak because small. Of course, the hot press forming process, the roughness increases during alloying but in a room for improving the coating adhesion to a certain level as such improvements is limited.
[66]
[67]
Thus, the implementation in the case by having to form a cavity in the plating layer of the steel phase, as described above in order to improve this, is that the voids collapse during the press forming next to the one that contributes to the increase of the roughness.
[68]
[69]
The area ratio occupied by voids in the cross-section of the surface layer is observed by cutting a coating layer of the steel sheet in the thickness direction be equal to or greater than 10% compared to the area of ​​the entire surface layer For this purpose, and may be greater than 15%. In this case also, as in the case of the steel sheet to hot press molding is improved, the surface roughness can significantly improve the corrosion resistance after coating and coating adhesion accordingly. Need not be then coated in accordance with coating adhesion or it particularly restricted the upper limit of the surface roughness in terms of corrosion resistance, the void ratio may be determined in conventional 70% or less or 60% or less. Method of measuring the pore rate can be used a method of measuring the level of a portion where the pores are present, but by using a can be for a number of image analyzer (Image Analyzer) In one kinds implementation example of the invention.
[70]
[71]
In the present invention, in order to form such a high proportion of the pores of the surface layer portion of coating layer The surface of the steel sheet, it may be a plating layer of an aluminum alloy plate layer, in the implementation of one kinds of cases can be the Al-Fe alloy plating layer. According to one implementation example of the present invention Al-Fe alloy plating layer can be obtained by alloying the Al-plated steel sheet in an appropriate condition. That is, the present time invention to heat the Al-plated steel sheet in the appropriate conditions, is taking place diffusion between Al and carry the steel sheet of the plating layer Fe Al and there is Fe alloy, using a phenomenon in which a large number of pores formed in the surface layer part in the process, will be.
[72]
[73]
At this time, to the formation of voids, and it is equal to or greater than the average content of Fe 30% by weight of the coating layer, may be at least more preferably 40% or more, more preferably 50% by weight. In other words, since a sufficient alloying take place can be a gap is obtained at the surface layer, the average content of Fe in the plating layer may be 30%, 40% or 50% by weight or more. The upper limit of the average content of Fe need not particularly set, it may decide to 80% by weight or less when considering the efficiency of the alloy. The mean content of Fe is, but the measurement method as meaning the average of the Fe content in the whole plated layer may have a different, the implementation cases the glow discharge spectroscopy (Glow Discharge emission Spectrometry; briefly GDS) method as a steel sheet from the surface of the coating layer when the surface was analyzed by then integrating the curve of Fe content according to the depth (thickness) that appears can be used by dividing it to a coating layer thickness. The criteria for judging the interface between the plated layer and the steel sheet, but there can be several, patients in this implementation may provide a point of the content of Fe 92% of the base metal Fe content results from the GDS to the interface between the plated layer and the steel sheet.
[74]
[75]
Steel sheet of the present invention is not particularly limited if the composition as a steel sheet for hot press forming, using a hot press forming. However, when subject to one aspect of the present invention in weight percent (composition of the present invention do not or less, expressed specifically different steel sheet and the plating layer is to be noted that that, based on the weight), C: 0.04 ~ 0.5%, Si: may have the following composition containing less than 0.02%: 0.01 ~ 2%, Mn: 0.01 ~ 10%, Al: 0.001 ~ 1.0%, P: 0.05% or less, S: 0.02% or less and N.
[76]
[77]
C: 0.04~0.5%
[78]
The C may be added in an appropriate amount as an essential element in order to raise the strength of the heat-treated member. That is, the C is more than 0.04% may be added in order to ensure sufficient strength of the heat-treated member. In one kinds of implementation cases the lower limit of the C content may be 0.1%. However, if the content is too high, the production of cold-series high heat serialized strength so when cold rolling the thermal series as well be cold rolled Castle greatly inferior, because it significantly reduced that weldability, sufficient cold rolling and points It may be added to 0.5% or less in order to ensure the weldability. In addition, the C content is below 0.45% may also limit the content thereof to below 0.4%.
[79]
[80]
Si: 0.01 ~ 2%
[81]
The Si, as well as to be added to the deoxidizing agent in steel making, hot to the strength of the press-formed member suppress carbide generated affects most greatly, and the martensite raesseu (lath) after martensite generated grain boundaries carbon in the hot press forming It concentrated to serve to secure a retained austenite. Thus, Si may be added in an amount of 0.01% or greater. In addition, it is possible to set the upper limit of the Si content to 2% in order to secure a sufficient plating property when performing an aluminum plated steel plate after rolling. In one kinds implemented cases of the present invention may limit the Si content to less than 1.5%.
[82]
[83]
Mn: 0.01 ~ 10%
[84]
The Mn may be added in an amount of 0.01% or greater in order not only to obtain the solid solution strengthening effect to lower the critical cooling rate for obtaining the martensite in the hot press forming member. Further, by maintaining the strength of the steel plate properly secure the hot press molding process workability and reduce the manufacturing cost, and the Mn content in terms of improving the spot weldability can be 10% or less, one implementation example of the invention in can be less than 9%, alternatively no more than 8%.
[85]
[86]
Al: 0.001~1.0%
[87]
The Al may be in the deoxidizing action in the steel with a Si added in an amount more than 0.001% can improve the cleanliness of steel. Further, the content of Al in order to prevent the Ac3 temperature is too high to allow the heat required for hot press forming in a suitable temperature range may be less than 1.0%.
[88]
[89]
P: 0.05% or less
[90]
Wherein the P is present as an impurity in the cavity, it is preferably small as the content of the glass. Thus, in one implementation example of the invention P it may be contained in an amount of 0.05% or less. In another thing implementation example of the invention P it may be limited to not more than 0.03%. Because P is small, it is advantageous small as the impurity element is not necessary to specify the upper limit of its content in particular. However, in order to reduce the excessive content of P because it may be raised and the manufacturing cost, in the case considered it may be the lower limit of 0.001%.
[91]
[92]
S: 0.02% or less
[93]
And the maximum content since the S is an impurity in the steel, an element inhibiting the ductility, weldability and impact properties of the members to 0.02% (preferably 0.01% or less). In addition the minimum content is less than 0.0001%, so the production cost may be raised, in the cases of one kinds of implementation of the present invention may be the lower limit of the content is 0.0001%.
[94]
[95]
N: 0.02% or less
[96]
The N may include as elements contained as impurities in the steel slab reduce the sensitivity to cracks at the time of continuous casting, the lower the content is more glass in order to secure the impact properties, and thus to more than 0.02%. It is necessary to particularly specify a lower limit, and may in consideration of the increase in manufacturing costs set the N content in one implementation cases more than 0.001%.
[97]
[98]
As required in the present invention, the sum more than one member selected from the group consisting of Cr, Mo and W in addition to the composition of the aforementioned steel: 0.01 ~ 4.0%, Ti, Nb, and the sum at least one from the group consisting of Zr and V: 0.001 ~ 0.4%, Cu + Ni: may be further added with one or more of 0.0001 ~ 0.01%: 0.005 ~ 2.0%, Sb + Sn: 0.001 ~ 1.0%, and B.
[99]
[100]
Cr, the sum at least one member selected from the group consisting of Mo and W: 0.01 ~ 4.0%
[101]
The Cr, Mo and W, so can ensure hardenability and improving the strength and grain refinement through the precipitation strengthening effect, these can be added to one or more than 0.01% in an amount based on the sum. It is also possible to limit the content thereof to below 4.0% to ensure the welding of the members. On the other hand, if the content of these elements exceeds 4.0%, the effect may be no more increase in the anti also an increase in cost due to the addition of extra elements if the limit amount because weak below 4.0%.
[102]
[103]
Ti, Nb, the sum over the selected one kind of the group consisting of Zr and V: 0.001 ~ 0.4%
[104]
The Ti, Nb and V enhance the fine precipitates formed in the heat-treated member plate, and may be added more than 0.001% because it is effective in the retained austenite stability and improved impact toughness by grain refinement the at least one of these in a total amount of the content of have. However, the amount added is that the effect may result in an increase in cost in excess ferroalloy is added, as well as be saturated if it exceeds 0.4%.
[105]
[106]
Cu + Ni: 0.005 ~ 2.0%
[107]
The Cu and Ni is an element for improving the strength by forming a fine precipitate. The sum of one or more of these components in order to obtain the effect described above can be made less than 0.005%. However, if the value exceeds 2.0%, since an excessive increase in cost, the upper limit should be 2.0%.
[108]
[109]
Sb + Sn: 0.001 ~ 1.0%,
[110]
The Sb and Sn is concentrated on the surface, the annealing heat treatment for an Al-Si plating can be suppressed that the Si or Mn oxide formed on the surface improves the plating property. In order to obtain this effect may be added more than 0.001%. However, since that amount is exceeded 1.0%, as well as excessive costs ferroalloy slab employed in the grain boundaries can cause the hot-rolled coil edge (edge) to crack the upper limit of 1.0%.
[111]
[112]
B: 0.0001~0.01%
[113]
Wherein B is an element with a small amount of addition, as well as be able to improve the hardenability, it is segregated on old austenite grain boundaries to suppress the brittleness of hot press forming member according to the grain boundary segregation of P and / or S. Thus, B may be added more than 0.001%. However, when it exceeds 0.01%, not only the effect is saturated, it results in brittleness in the hot rolling may be the upper limit of 0.01%, one implementation of the cases may be the B content to 0.005% or less.
[114]
[115]
As the remaining portion other than the above components may be made of iron and inevitable impurities, if the components that may be included in the steel sheet for hot press forming is not specifically limited.
[116]
[117]
[0475] One example of a method of manufacturing a steel sheet for hot press forming according to one aspect of the present invention as follows. However, the method of manufacturing way of the steel sheet for hot press forming that is a steel sheet for hot press forming according to the present invention is used as one kinds of illustrative not necessarily should be made by the present manufacturing method, meet any production process, even the claims of the present invention If it is necessary to note that there is no problem in using to implement each implementation example of the invention.
[118]
[119]
Steel sheet of the present invention can be obtained by the use, and the hot-rolled or cold-rolled steel sheets possessing, subjected to molten aluminum plating on the surface of the carrying plate, the annealing treatment to the plated steel sheet.
[120]
[121]
[Aluminum plating process;
[122]
In one kinds implemented cases of the present invention prepare the carrying plate, and the aluminum plating process, the surface of the carrying plate with the appropriate conditions and volumes taken for obtaining the aluminum-plated steel sheet (coil) is performed.
[123]
[124]
One side of 30 ~ 200g / m per second to hold the steel sheet surface with a coating weight of aluminized
[125]
It can be an aluminum plating process on the surface of the rolled steel plate. Aluminum coatings are typically AlSi plating named type I (containing more than 80% Al and Si of 5 to 20%, and can also include additional elements as necessary), or, required to contain at least 90% of the Al is named type II plating it can be used both to include additional elements in accordance with the. It can be a molten aluminum-plated to form a plated layer, and may be an annealing treatment to a steel sheet prior to plating. Proper coating weight when plating one side of the reference to 200g ~ 30 / m 2 a. If the coating weight is too much, and it may take two hours to excessive alloying up to the surface, whereas if the coating weight is too low, it is difficult to obtain sufficient corrosion resistance.
[126]
[127]
After plating the take-up tension ~ 0.5 5 kg / mm 2 referred to as
[128]
When the steel sheet obtained by winding a coil after plating, and to control the winding tension of the coil. Carried out may vary the alloying behavior and surface quality of the coil during annealing process after the adjustment in accordance with the winding tension of the coil.
[129]
[130]
[Annealing treatment]
[131]
Subjected to annealing treatment under the following conditions with respect to the aluminum-coated steel sheet by the above-described process to obtain an aluminum alloy-plated steel sheet.
[132]
[133]
30 minutes at a range of 550 ~ 750 ℃ ​​in to appeal to 50 hours based embodiment
[134]
Aluminum-coated steel sheet (coil) is heated in (Batch annealing furnace to put appeal. When heating the steel sheet, annealing the target temperature and the holding time is in the range 550 ~ 750 ℃ ​​based on the steel sheet temperature within (in the present invention the temperature range in it is preferable that the material is continued for 30 minutes ~ 50 hours at called the heating temperature to a maximum temperature which is reached). also here referred to as the holding time is the time to the start after the coil temperature reaches the target temperature cooling. of the invention one kinds of implementation cases in may alloying can and if not sufficiently done is because the plating layer during roll leveling can be taken off the heating temperature for a sufficient alloyed with more than 550 ℃. in addition, and prevent the surface oxides are excessively produced the heating temperature in order to ensure that welding can be less than 750 ℃. in addition, at the same time to sufficiently ensure the productivity of the plated layer And the holding in order to prevent the time can be set to 30 minutes ~ 50 hours. One implementation cases of the temperature of the steel sheet of the present invention have the form of a pattern that the temperature continues to rise without cooling process until it reaches the heating temperature can.
[135]
[136]
To the average rate of temperature increase to 20 ~ 100 ℃ / h heated to the heating temperature
[137]
When heating the steel sheet in the above-described heating temperature, in order to ensure sufficient productivity and uniformly alloying the coating layer around the steel sheet (coil) in the steel sheet (coil) temperature reference for the entire temperature interval (interval to the heating temperature from room temperature) the average rate of temperature increase can be such that the 20 ~ 100 ℃ / h. In addition, while able to control the overall average rate of temperature rise is above the numerical range, the one kinds implementation example of the invention was to achieve to a control with a temperature rising rate of the specific temperature range object of the present invention, as will be described later. In another thing implemented cases of the present invention may set an average rate of temperature rise of the whole temperature range to 70 ℃ /.
[138]
[139]
Heating to an average temperature increase rate of 400 ~ 500 ℃ interval during the temperature increase by 1 ~ 15 ℃ / h
[140]
For while the rolling oil is left at this temperature range in one kinds implemented cases of the present invention, which is vaporized a rolling oil entrained during rolling avoid causing such surface staining to ensure sufficient productivity, the average temperature rise rate of 400 ~ 500 ℃ during the temperature increase period 1 and can be heated by a 15 ℃ / h. In one kinds implementation example of the invention, and the lower limit of the average temperature rise rate of the heating was 400 ~ 500 ℃ interval to a 4 ℃ / hr, the lower limit of the other thing implementation cases the average temperature rising rate of 400 ~ 500 ℃ interval during the temperature increase It may be a 5 ℃ / hr.
[141]
[142]
During the temperature increase an average heating temperature of the heating temperature range -50 ℃ ~ elevated temperature by heating the speed to 1 ~ 15 ℃ / h
[143]
Alloyed during sticking preventing the (co days the surface is a surface defect is attached drop by alloying), and the average rate of temperature increase of the heating temperature of -50 ℃ ~ a heating temperature during the temperature increase period in order to allow the pores and can be formed sufficiently, sufficient productivity a can be heated to a 1 ~ 15 ℃ / h. In one kinds implementation example of the invention the lower limit of the average rate of temperature increase of the interval may be set to 4 ℃ / h, may also be implemented in another thing cases set a lower limit of the average rate of temperature increase of said interval to 5 ℃ / h.
[144]
[145]
Should the difference between the temperature in the atmosphere of the steel sheet temperature to appeal placed in 5 ~ 80 ℃
[146]
Heating of the general appeal placed takes the way of heating a steel sheet (coil) through the atmosphere of a temperature rise in the annealing than a method of heating a steel sheet (coil) directly. The difference between the ambient temperature and the steel sheet temperature in this case may be the difference between the ambient temperature and the coil temperature to but avoiding, minimizing location-specific material and coating quality deviation plates, based on the heat treatment target temperature is reached the time to less than 80 ℃ have. Ideally, the temperature difference is small and that by using a slower rate of temperature increase as possible, so that may be difficult to meet the average rate of temperature rise conditions, given this can be more than 5 ℃. Here, the temperature of the steel sheet is meant a measure of the temperature (which means the lowest part in a coil), a charged plate (coil), a bottom portion, and the ambient temperature means a temperature measured at the center of the inner space of the furnace .
[147]
[148]
[Cooling step]
[149]
[150]
After annealing by cooling at a rate of 500 ℃ 50 ℃ / h or less
[151]
After holding for a predetermined time at a target temperature of the aluminum alloy-plated steel sheet (coil) it is cooled. A cooling method can be applied a variety of methods such as ronaeng, air-cooled, water-cooled, there is no particular limitation on the average cooling rate of the entire cooling period, it is safe to rapid cooling in order to improve productivity. However, the cooling rate of the sticking temperature range prevents the defect and then heated to 500 ℃ to fully form the air gap, while ensuring uniformity of the material may be less than 50 ℃ / h. If the lower limit is not particularly limited and can be in consideration of the productivity to a 1 ℃ / h or more.
[152]
Mode for the Invention
[153]
It will be described the present invention to the following examples in more detail. However, the embodiment of the following examples is to be noted in that not intended to limit the may make the scope of the present invention to refine to illustrate the invention. The scope of the present invention is because it is determined by what is reasonable to infer from this information and set forth in the claims.
[154]
[155]
(Example)
[156]
[157]
Producing a steel sheet
[158]
[159]
Examples 1
[160]
To having a composition shown in Table 1 to prepare a cold-rolled steel sheet for hot press forming. With the surface of the steel sheet Al-9% Si-2.5% Fe composition was coated to the surface of the steel type I in the plating bath. When the plating coating weight per side one side is 70g / m 2 was controlled by, a take-up tension after plating 2.2kg / mm 2 it was wound by the coil adjusted.
[161]
[162]
TABLE 1
element C And Mn Al P S N Additional elements
content(%) 0.21 0.2 1.3 0.03 0.01 0.003 0.005 0.03, B, 0,002 Cr 0.2

[163]
Under the following conditions based on the appeal to the plated steel sheet it was heated to 650 ℃.
[164]
The overall average heating rate of up to 650 ℃: 20 ℃ / h
[165]
400 ~ 500 ℃ average temperature rising rate of the temperature range: 10 ℃ / h
[166]
600 ~ 650 ℃ average temperature rising rate of the temperature range: 10 ℃ / h
[167]
The temperature difference between the atmosphere and the coil at a heating temperature: 30 ℃
[168]
[169]
It was continued for 10 hours at the same temperature after heating, and then cooled after the steel sheet by 40 ℃ / h average cooling rate up to 500 ℃, cooled to 55 ℃ / h average cooling rate of up to 100 ℃ to obtain a steel sheet for hot press forming .
[170]
[171]
Results The analysis of the plating layer of the steel sheet to a GDS analyzer was also obtained in the form of components, such as the profile 2, the average was calculated based on this Fe content is 51.5% by weight. Of the steel sheet cross-sectional shape is found to be as shown in Fig. 3 had a plating layer is formed on the outer surface of the substrate steel sheet, the area ratio of voids formed in the portion corresponding to the surface layer to the thickness direction 10㎛ point from the surface of the formed plated layer 22.8% there was.
[172]
[173]
To honor two
[174]
The steel type I in a plating bath having Al-9% Si-2.5% Fe composition to the surface of the steel sheet having a composition of Table 1 was coated the surface. When the plating coating weight per side one side is 80g / m 2 was adjusted was adjusted to, a take-up tension after plating 2kg / mm 2 was wound by the coil adjusted.
[175]
[176]
In a appeal since the plated steel plate placed in the following conditions and heated to 700 ℃.
[177]
The overall average heating rate of up to 700 ℃: 20 ℃ / h
[178]
400 ~ 500 ℃ average temperature rising rate of the temperature range: 12 ℃ / h
[179]
650 ~ 700 ℃ average temperature rising rate of the temperature range: 8 ℃ / h
[180]
The temperature difference between the atmosphere and the coil at a heating temperature: 40 ℃
[181]
[182]
It was maintained at the same temperature for 1 hour after the heating, and then cooled after the steel sheet by 30 ℃ / h average cooling rate up to 500 ℃, cooled to 57 ℃ / h average cooling rate of up to 100 ℃ to obtain a steel sheet for hot press forming .
[183]
[184]
A plating layer of the steel sheet could be obtained form the component profile of the same and Fig. 4 the results analyzed in GDS analyzer, the average calculated based on this Fe content was 53.7% by weight. Of the steel sheet cross-sectional shape is found to be as shown in FIG. 5 was a plating layer is formed on the outer surface of the substrate steel sheet, the area ratio is 28.5% of the pores formed in the portion corresponding to the surface layer to the thickness direction 10㎛ point from the surface of the formed plated layer there was.
[185]
[186]
Comparative Example 1
[187]
But to the same manner as Example 1 was carried out, only the aluminum-plated steel sheet and the plating is not carried out the heating and cooling in Comparative Example 1.
[188]
[189]
A plating layer of the steel sheet could be obtained in the form of a component profile as shown in Fig. 6 the results analyzed in GDS analyzer was an average calculated based on this Fe content is 23.6% by weight. Of the steel sheet cross-sectional configuration is confirmed that pores do not substantially formed at the portion corresponding to the surface layer portion of the outer surface to hold the thickness direction 10㎛ point was a plating layer is formed, from the surface of the plated layer formed on the steel sheet as shown in Fig. 7 there was. The area ratio of the pores formed was 0%.
[190]
[191]
Comparative Example 2
[192]
The foot, but the same as the honor 2 was an aluminum-plated steel sheet plated only exemplary and are not carried out the heating and cooling in Comparative Example 2.
[193]
[194]
A plating layer of the steel sheet could be obtained form the component profile of the same and Fig. 8 the results analyzed in GDS analyzer was an average calculated based on this Fe content is 21% by weight. Of the steel sheet cross-sectional configuration is confirmed that as shown in FIG. 9 had a plating layer is formed on the outer surface of the substrate plate, that gap is not substantially formed at the portion corresponding to the surface layer to the thickness direction 10㎛ point from the surface of the formed plated layer there was. The area ratio of the pores formed was 0%.
[195]
[196]
Comparative Example 3
[197]
The steel type I in a plating bath having Al-9% Si-2.5% Fe composition to the surface of the steel sheet having a composition of Table 1 was coated the surface. When the plating coating weight per side one side is 90g / m 2 was adjusted was adjusted to, a take-up tension after plating 2kg / mm 2 was wound by the coil adjusted.
[198]
[199]
In a appeal since the plated steel plate placed in the following conditions and heated to 650 ℃.
[200]
The overall average heating rate of up to 650 ℃: 50 ℃ / h
[201]
400 ~ 500 ℃ average temperature rising rate of the temperature range: 10 ℃ / h
[202]
600 ~ 650 ℃ average temperature rising rate of the temperature range: 70 ℃ / h
[203]
The temperature difference between the atmosphere and the coil at a heating temperature: 30 ℃
[204]
[205]
It was continued for 10 hours at the same temperature after heating, since then cooling the steel sheet to 45 ℃ / h average cooling rate up to 500 ℃, cooled to 60 ℃ / h average cooling rate of up to 100 ℃ to obtain a steel sheet for hot press forming .
[206]
[207]
A plating layer of the steel sheet could be obtained form the component profile of the same in Fig. 10 analyzes this result to a GDS analyzer, the average calculated based on this Fe content was 48.4% by weight. Of the steel sheet cross-sectional shape is found to be as shown in FIG. 11 was a plating layer is formed on the outer surface of the substrate steel sheet, the area ratio is 3.5% of the pores formed in the portion corresponding to the surface layer to the thickness direction 10㎛ point from the surface of the formed plated layer there was.
[208]
[209]
Hot press forming
[210]
[211]
The Examples 1, 2 and Comparative Examples 1 to were the three plates of the holding and then heated to 950 ℃ 5 minutes at this temperature, subjected to hot press forming to rapidly cooled under pressure by a press after obtain a hot press molded.
[212]
[213]
By observing a cross-section of a member obtained was observed with a surface roughness (Ra), the results are shown in Table 2 below.
[214]
[215]
TABLE 2
division The surface roughness (Ra)
Examples 1 2.01
To honor two 2.23
Comparative Example 1 1.12
Comparative Example 2 1.27
Comparative Example 3 1.48

[216]
In contrast as can be found in Table 2, Inventive Examples 1 and 2 are each a surface roughness (Ra) of 2.01 and 2.23㎛ Comparative Example 1, Comparative Example 2 and Comparative Example 3, the surface roughness (Ra) of 1.12, 1.27 and it was only 1.48㎛.
[217]
[218]
Extent by carrying out the above-described phosphate treatment and electrodeposition coating on each foot member obtained from the fame and the comparative examples to form a four-way blemish on the surface of the steel sheet, and then the composite corrosion test (Cyclic corrosion test) the blister occurs in cross-Hm a was observed. Composite corrosion test was a one cycle 24 of a "humid atmosphere exposed 2 hours cooled 3 hours salt spray exposure 2 hours drying one hour humid atmosphere exposure 6 hours drying 2 hours humid atmosphere exposure 6 hours - dried for 2 hours, the time and held a total of 50 cycles. Examples 1 and 2 can both confirm that the maximum width of the block list is 1mm or less, whereas, in Comparative Examples 1, 2 and 3 is the maximum width of the block list that the corrosion resistance after painting poor compared with the invention example as 3.2, 2.9 and 2.4mm respectively, there was.
[219]
[220]
Thus, it was confirmed the beneficial effects of the present invention.

Claims

[Claim 1]Including possession of the steel sheet and the plated layer formed on a surface of the carrying plate, and the cross-sectional area ratio of paint adhesion and corrosion resistance after painting 10% or more area compared to the entire surface layer occupied by the pores in the surface layer is observed by cutting the plated layer in the thickness direction, excellent steel sheet for hot press forming member.
[Claim 2]
The method of claim 1 wherein 15% or more coating adhesion and corrosion resistance after coating with excellent hot press molded steel sheet for use in area compared to the area ratio of the whole surface layer occupied by the voids in the cross-section of the surface layer is observed by cutting the plated layer in the thickness direction.
[Claim 3]
According to claim 1, wherein said plating layer is an aluminum alloy plate layer of paint adhesion and corrosion resistance after coating with excellent hot press molded steel sheet.
[Claim 4]
According to claim 3, wherein the aluminum alloy plating layer is an average Fe content of not less than 30% by weight, coating adhesion and corrosion resistance after coating with excellent hot press molded steel sheet for use in the.
[Claim 5]
According to claim 3, wherein the aluminum alloy plating layer is an average Fe content of not less than 40% by weight, coating adhesion and corrosion resistance after coating with excellent hot press molded steel sheet for use in the.
[Claim 6]
The method of claim 1, wherein the carrying plate in weight% C: 0.04 ~ 0.5%, Si: 0.01 ~ 2%, Mn: 0.01 ~ 10%, Al: 0.001 ~ 1.0%, P: 0.05% or less, S: 0.02 % or less, N: 0.02% or less, the balance Fe and other inevitable impurities, with the composition containing the coating material adhesion and corrosion resistance after coating with excellent hot press molded steel sheet.
[Claim 7]
The method of claim 6, wherein the composition of the possession of the steel sheet in weight%, Cr, Mo, and the sum from the group consisting of W or more selected one kinds: 0.01 ~ 4.0%, Ti, Nb, at least one from the group consisting of Zr and V sum: 0.001 ~ 0.4%, Cu + Ni: 0.005 ~ 2.0%, Sb + Sn: 0.001 ~ 1.0%, and B: On the of 0.0001 ~ 0.01% coating adhesion further comprising at least one application and having excellent hot press forming corrosion members steel sheet.
[Claim 8]
Step aluminum coated surface of the steel sheet by taking possession of the ticket, and to obtain an aluminum-plated steel sheet; Step by annealing aluminum plated steel sheet to obtain an aluminum alloy-coated steel sheet; And a method for manufacturing a steel sheet for hot press forming member comprises the step of cooling the aluminum alloy-plated steel sheet, the aluminum coating weight is 30 ~ 200g / m to one side of the steel plate based on 2 a, and the winding tension during the winding 0.5 ~ 5kg / mm 2 with, and the annealing is carried out at a heating temperature range of 550 ~ 750 ℃ 30 bun ~ 50 hours at a appeal placed, when heated in room temperature during the annealing to the heating temperature, the average temperature increase rate 20 ~ 100 ℃ / h, but as a, a 400 ~ 500 ℃ average temperature rise rate of 1 ~ 15 ℃ / h of the interval, and the rate of temperature increase of the heating temperature of the heating temperature range -50 ℃ ~ to 1 ~ 15 ℃ / h, based the furnace appeal ambient temperature and the steel plate and the temperature difference between a 5 ~ 80 ℃, the aluminum alloy plating in the step of cooling the steel sheet to 500 ℃ after paint coating adhesion and to cool at a rate of 50 ℃ / h or less hot press forming member excellent in corrosion resistance method for manufacturing a steel sheet for use.
[Claim 9]
The method of claim 8, wherein the carrying plate in weight% C: 0.04 ~ 0.5%, Si: 0.01 ~ 2%, Mn: 0.01 ~ 10%, Al: 0.001 ~ 1.0%, P: 0.05% or less, S: 0.02 % or less, N: method of not more than 0.02%, the balance Fe and other coating adhesion with the steel sheet for hot press forming member excellent corrosion resistance after coating having a composition that includes unavoidable impurities.
[Claim 10]
Of claim 9, wherein the composition of the possession of the steel sheet in weight%, Cr, Mo, and the sum from the group consisting of W or more selected one kinds: 0.01 ~ 4.0%, Ti, Nb, at least one from the group consisting of Zr and V sum: 0.001 ~ 0.4%, Cu + Ni: 0.005 ~ 2.0%, Sb + Sn: 0.001 ~ 1.0%, and B: On the of 0.0001 ~ 0.01% coating adhesion further comprising at least one application and having excellent hot press forming corrosion method of producing a steel sheet member.