[0001]The present invention, Al-based plated steel sheet, to hot pressing method and automotive parts of the Al-based plated steel sheet.
　This application, claims to 04 May 18, 2012, and Japanese Patent Application No. 2012-095014, filed in Japan, on 04 May 25, 2012, priority based on has been and Japanese Patent Application No. 2012-100266, filed in Japan and, the contents of which are incorporated here.
BACKGROUND
[0002]

　Recently, for the prevention of environmental protection and global warming, but there is an increasing inhibit request the consumption of fossil fuels, the demand has affected to various manufacturing industries. For example, rather than the exception for the automobile that are essential to the day-to-day life and activities as a means of transportation, such as improvement of fuel consumption due to the weight of the vehicle body is being sought. However, in the automobile, to simply reduce the weight of the vehicle body is not allowed on the product quality, it is necessary to ensure proper safety.
[0003]
Many automotive components are iron, are formed in particular steel, to reduce the mass of the steel sheet, it is important for reducing vehicle weight. However, as mentioned above, it is not allowed to simply reduce the mass of the steel sheet, it is required to ensure the mechanical strength of the steel sheet. Such demand for steel plate, not automobile manufacturing industry alone, are similarly made in various manufacturing industries.
[0004]
Therefore, by increasing the mechanical strength of the steel sheet, even thinner than the steel sheet that was previously used, the steel sheet capable of enhancing maintain or mechanical strength, research and development have been conducted.
[0005]

In general, materials having a high mechanical strength, in a molding process of bending, etc. Since the shape fixability is lowered, the case of processing into complex shapes, processing itself becomes difficult. As a means for solving the problems of the moldability, so-called, a "hot press method (hot stamping method, a hot press method, die quenching method, or also referred to as press hardening)."
[0006]
The hot pressing process, the material is a molded object, once, and press working is softened by heating to a high temperature, then cooled. According to this hot pressing process, the material, once so softened by heating to a high temperature, it is possible to easily press-working, further, by hardening by cooling after the molding, increasing the mechanical strength of the material. Accordingly, by hot pressing, it is possible to obtain a good shape fixability and high moldings mechanical strength is achieved.
[0007]
However, the case of applying the hot press method to a steel sheet, for example, since the heating to temperatures higher than 800 ° C., the iron surface is oxidized scale (oxides) is produced. Thus, after hot pressing, a step of removing the scale (descaling process) is required, the productivity is lowered. Further, when the member that requires corrosion resistance, after processing, may be necessary to add anti-rust treatment or metallization to the surface of the member, and a surface cleaning step, the surface treatment step is required, also the productivity is lowered.
[0008]
As a method of suppressing such a decrease in productivity, there is a method of applying a coating to advance the steel sheet. Generally, as a coating material for steel plates, such as organic materials and inorganic materials, various materials are used. Among them, zinc (Zn) based plated steel sheet with a sacrificial protection effect on the steel sheet, from the viewpoint of corrosion prevention performance and production technology, widely used in the automobile steel sheets.
[0009]
However, the heating temperature in the hot press (700 ~ 1000 ℃), the decomposition temperature and the organic material is higher than the melting point of the metal material such as Zn-based, when heated, the plated layer of the surface melted, evaporated, the surface sometimes properties are significantly deteriorated.
[0010]
Therefore, used as a steel sheet subjected to hot pressing, for example, organic materials coated or steel having a melting point subjected to metallization high aluminum (Al) system compared to the metallization of Zn-based, so-called, an Al-based plated steel sheet it is desirable to.
[0011]
When applying a metal coating of the Al-based steel sheet, it is possible to prevent the scale generated on the surface of the steel sheet, since steps such as descaling step is unnecessary, the productivity is improved. Further, since the metallization of the Al-based also anticorrosive effect is also improved corrosion resistance after painting.
[0012]
Patent Document 1, the metallization of the Al-based, a method of applying is disclosed an Al-based plated steel sheet subjected to a steel plate of a predetermined component composition to hot press.
[0013]
However, when applying a metal coating of the Al-based steel sheet, by hot pressing prior to the heating conditions, the Al-based metallization is melted, iron (Fe) to diffuse a steel plate and aluminum and compounds Al- Fe compounds are formed, to the surface of the steel sheet, there is a case where Al-Fe compound (hereinafter sometimes referred to as "Al-Fe alloy layer") are stacked. Al-Fe alloy layer are the rigid, in contact with the mold during press working, there is a case where machining scratches are generated on the surface of the steel sheet.
[0014]
Originally, Al-Fe alloy layer is relatively surface hardly slip, poor lubrication. Furthermore, Al-Fe alloy layer are the hard, relatively cracks easily enters cracks in the plating layer, the plating layer is then powdering, moldability is likely to decrease. Additionally, or adhering powder Al-Fe alloy peeled from Al-Fe alloy layer in the mold, is abraded strongly surface of Al-Fe alloy layer, powder of Al-Fe alloy adheres to the mold or Then, the quality of the press-molded product is reduced.
[0015]
Therefore, it is necessary to remove a powder of Al-Fe alloy adhesion to the mold during repair and contribute to productivity reduction and cost increase.
[0016]
Furthermore, Al-Fe compounds, because poor reactivity with the phosphate treatment, coating (phosphate coating) the chemical conversion treatment is a pretreatment electrodeposition coating is not generated. Al-Fe alloy layer, even without the chemical conversion coating, the coating adhesion is good, by forming the Al-Fe alloy layer having a sufficient adhesion amount, but also a good corrosion resistance after painting, Al- increasing the amount of adhered Fe alloy layer, thereby causing the mold adhesion described above.
[0017]
The cause of the mold adhesion, as described above, peeling and the Al-Fe alloy layer, such as a surface abrasion of the Al-Fe alloy layer. The improved lubricity of the surface film, the latter mold adhesion but (rubbing adhesion) is improved, the improvement of the former of the mold adhesion (peel adhesion) is relatively small. The improvement in the former of the mold adhesion, reducing the adhesion amount of Al-Fe alloy layer is most effective. However, reducing the amount of adhered Al-Fe alloy layer, corrosion resistance decreases.
[0018]
In contrast, Patent Document 2, for the purpose of preventing occurrence of processing flaws, on a steel sheet of a given component composition is subjected to metallization of the Al-based, further on the metal coating of the Al-based, silicon (Si ), zirconium (Zr), titanium (Ti), and an inorganic compound layer, an organic compound layer containing at least one phosphorus (P), or, to form their composite compound film is disclosed.
[0019]
In such a surface film formed steel sheet surface film even at the time of press working after heating remains, it is possible to prevent the occurrence of machining flaws during pressing. Incidentally, Patent Document 2, since the surface film acts as a lubricant during pressing, but moldability is described to be improved, in fact, sufficient lubricity can be obtained, a new lubricant and, there is a need for an alternative means.
[0020]
Patent Document 3, in the hot press of galvanized steel sheet, a method of solving the surface deterioration due to evaporation of zinc plating layer is disclosed. Specifically, a high melting point of zinc oxide (ZnO) layer on the surface of the galvanized layer was produced as a barrier layer to prevent evaporation of the underlying zinc plating layer.
[0021]
However, the technique of Patent Document 3 is one that assumes a zinc plating layer. With regard to Al, but allows inclusion of up to 0.4% in the galvanizing layer, Al concentration is the lower is better, substantially, the technology does not assume the metallization of the Al-based. Incidentally, the problem of the technique of Patent Document 3, because it is the evaporation of Zn galvanized layer, the high melting point Al-based metal coating is an issue which can not naturally occur.
[0022]
Patent Document 4, a wurtzite type compound coated on the surface of the Al-based plated steel sheet, a technique for improving the hot lubricity and chemical conversion treatability is disclosed. This technique is effective in improving the lubricity, but also improves the corrosion resistance after painting, because of the lubricity improving the adhesion amount of the coating is 2 g / m in Zn terms 2 requires approximately, more to obtain a stable lubricity, 3 g / m 2 is required to be about. However, the 3 g / m 2 is about 1.5μm in terms of the adhesion amount of the coating of the thickness of the film. In such a thickness (deposition amount 3 g / m 2 if more than), that film resistance increases, decreases the spot weldability, as a result, a possibility that the cross tensile strength decreases is assumed. Therefore, at a coverage of smaller amounts of coating techniques for improving the lubricity it is demanded.
CITATION
Patent Document
[0023]
Patent Document 1: Japanese Patent 2000-38640 JP
Patent Document 2: Japanese Patent 2004-211151 JP
Patent Document 3: Japanese Patent 2003-129209 JP
Patent Document 4: International Publication WO2009 / 131 233 pamphlet
Summary of the Invention
Problems that the Invention is to Solve
[0024]
As described above, plated steel sheets subjected to Al-based plating refractory (Al-based plated steel sheet), the corrosion resistance are promising as automotive steel sheets is required, various proposals for application to hot press It has been made. However, conventional Al-based plated steel sheet, because can not be obtained good lubricity to Al-Fe alloy layer formed on the surface, poor press formability during hot pressing, applicable to hot pressing a complicated shape it was difficult to.
[0025]

　The present invention has been made in view of the circumstances described above, has a good lubricity than conventional, and moldability and which can realize an improvement in productivity Al-based plated steel sheet during hot pressing, the hot pressing method, and an object of the invention to provide a car part made from the hot press method.
Means for Solving the Problems
[0026]
The present invention adopts the following means in order to achieve the object according to the above-mentioned problems are eliminated. That,
(1) Al-based plated steel sheet according to one embodiment of the present invention, steel plate and; formed on one surface or both surfaces of the steel sheet, and Al-based plating layer containing 85% or more of at least Al in mass%; the Al It comprises; laminated on the surface of the system plating layer, and a surface coating layer containing ZnO and one or more lubricity enhancing compound.
[0027]
(2) In the Al-based plated steel sheet according to (1), wherein the lubricity enhancing compound may be a compound containing one or more transition metal elements.
[0028]
(3) In the Al-based plated steel sheet according to the above (2), wherein the transition metal element, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Mo, W, La, and, of Ce may be any one or more of them.
[0029]
(4) In the Al-based plated steel sheet according to the above (2), in the surface coating layer, the mass ratio with respect to the ZnO of the lubricity enhancing compound containing the transition metal element may be 1-40%.
[0030]
(5) In the Al-based plated steel sheet according to (1), wherein the lubricity enhancing compound may be a compound containing one or more typical elements.
[0031]
In Al-based plated steel sheet according to (6) above (5), the typical element, Mg, Ca, Sr, Ba, P, Sn, and may be any one or more of Ge.
[0032]
(7) In the Al-based plated steel sheet according to (5), in the surface coating layer, the mass ratio with respect to the ZnO of the lubricity enhancing compound containing the typical element may be 5-30%.
[0033]
(8) In the Al-based plated steel sheet according to any one of the above (1) to (7), wherein the surface coating layer is, 0.3 ~ 7 g / m with Zn terms 2 contain the ZnO of it may be.
[0034]
(9) In the Al-based plated steel sheet according to any one of the above (1) to (8), wherein the surface coating layer is, though the mass ratio with respect to the ZnO is contained 5-30% of the organic compound further it may be.
[0035]
　Further,
the hot pressing process of the Al-based plated steel sheet according to one embodiment of the (10) The present invention, an Al-based plated steel sheet according to any one of the above (1) to (9), and heated after blanking , then, it is press-molded.
[0036]
(11) hot pressing method of Al-based plated steel sheet according to (10), said at press forming prior to the heating, the Al-based peak metal temperature of from 10 ° C. lower temperature plate temperature is from 50 ° C. of the plated steel sheet the average heating rate to reach may be 10 ~ 300 ° C. / sec.
[0037]
(12) In the hot pressing method of Al-based plated steel sheet according to (11), the heating before the press molding may be performed by electrical heating or induction heating.
[0038]
　Furthermore,
automotive parts according to one embodiment of the present invention (13) is produced by hot pressing method of Al-based plated steel sheet according to any one of the above (10) to (12).
Effect of the invention
[0039]
According to the present invention has good lubricating properties than conventional, and moldability and productivity possible Al-based plated steel sheet realize improvement of at hot pressing, a method of hot pressing, and hot pressing the It can provide automotive parts manufactured by the method.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040]
A layer structural diagram of the Al-based plated steel sheet according to the first embodiment of FIG. 1A] present invention.
A layer structural diagram of the Al-based plated steel sheet according to the second embodiment of FIG. 1B] present invention.
As an example of the automobile parts [2] The present invention is a diagram showing an external view of a center pillar stiffener.
It is a diagram showing an embodiment of FIG. 3] Al-based apparatus for evaluating the hot lubricity of the plated steel sheet.
Is a diagram showing the relationship between the [4] and the content of zinc oxide surface coating layer (Zn equivalent amount) and the film peeling rate.
It is a diagram showing a relationship between [5] and the content of zinc oxide surface coating layer (Zn equivalent amount) and the hot lubricity (coefficient of friction).
[6] and the content of zinc oxide surface coating layer (Zn equivalent amount) and is a diagram showing the relationship between the intensity of the spot joint.
DESCRIPTION OF THE INVENTION
[0041]
It will be described in detail with reference to the drawings an embodiment of the present invention.
First Embodiment
　First, a description will be given of a first embodiment of the present invention. Figure 1A is a diagram showing a layer structure of the Al-based plated steel sheet 10 according to the first embodiment. As shown in Figure 1A, the Al-based plated steel sheet 10 according to the first embodiment, the steel plate 11, the Al-based plating layer 12 formed on one side (e.g., upper surface) of the steel sheet 11, the Al-based plating layer 12 and a formed surface coating layer 13. in the surface.
　In FIG. 1A, on one side of the steel sheet 11, but illustrates a case where Al-based plating layer 12 and the surface coating layer 13 is formed, Al-based plating layer on both surfaces of the steel plate 11 12 and the surface coating layer 13 There may be formed.
[0042]
　Steel 11 serves as a substrate of Al-based plated steel sheet 10, the required mechanical properties (tensile strength, yield point, elongation, diaphragm, hardness, impact value, fatigue strength, and the like creep strength of the machine having the characteristics) about the deformation and fracture. The steel plate 11 is, for example, by mass%, of from 0.1 to 0.4% carbon (C), 0.01 ~ 0.6% of silicon (Si), 0.5 ~ 3% of manganese (Mn) 0.01 to 0.1% titanium (Ti), and contain such 0.0001 to 0.1% of boron (B), and containing the remainder of iron (Fe) and unavoidable impurities.
[0043]
The following describes the role of each element contained in the steel sheet 11. In the following description,% means mass%.
[0044]
Carbon is an element for ensuring the mechanical strength of the steel sheet 11. If the carbon content of the steel sheet 11 is less than 0.1%, no sufficient mechanical strength can be obtained. On the other hand, when the carbon content of the steel sheet 11 is more than 0.4%, although the hardness of the steel sheet 11 (mechanical strength) is increased, the melting cracking is likely to occur in the steel plate 11. Therefore, the carbon content of the steel sheet 11 is preferably 0.1 to 0.4%.
[0045]
Silicon, like carbon, is an element for ensuring the mechanical strength of the steel sheet 11. If the silicon content of the steel sheet 11 is less than 0.01%, the strength improvement effect is not exhibited, sufficient mechanical strength can be obtained. Meanwhile, silicon, because even oxidizable elements, the silicon content of the steel sheet 11 is more than 0.6%, and reduced wettability when performing the hot dip plated steel sheet 11, non-plating occurs. Thus, silicon content of the steel sheet 11 is preferably 0.01 to 0.6%.
[0046]
Manganese increases the hardenability of the steel sheet 11, which is an element for increasing the strength of the steel plate 11. Further, manganese combines with sulfur is unavoidable impurities in the steel sheet 11 (S) generates a manganese sulfide (MnS), also serves to prevent hot shortness of the steel sheet 11 by sulfur. If the manganese content of the steel sheet 11 is less than 0.5%, its addition effect is not exhibited. On the other hand, when the manganese content of the steel sheet 11 is more than 3%, the residual γ phase of the steel sheet 11 is large and becomes the strength decreases. Therefore, manganese content of the steel sheet 11 is preferably 0.5 to 3%.
[0047]
Titanium is a strength improving element, also, is an element for improving the heat resistance of the Al-based plating layer 12. If the titanium content of the steel sheet 11 is less than 0.01%, no strength improving effect and heat resistance improving effect is obtained. On the other hand, when the titanium content of the steel sheet 11 is more than 0.1%, carbides and nitrides are generated steel sheet 11 ends up softening, required mechanical strength can not be obtained. Therefore, the titanium content of the steel sheet 11 is preferably from 0.01 to 0.1%.
[0048]
Boron increases the hardenability of the steel sheet 11, which is an element for improving the strength of the steel sheet 11. If the boron content of the steel sheet 11 is less than 0.0001%, the strength improvement effect is not exhibited. On the other hand, when the boron content of the steel sheet 11 is more than 0.1%, inclusions are generated, the fatigue strength of the steel sheet 11 is reduced. Accordingly, the boron content of the steel sheet 11 is preferably from 0.0001 to 0.1 percent.
[0049]
Incidentally, the steel sheet 11, the inevitable impurities incorporated during the manufacturing process, may be contained in an amount that does not impair the mechanical properties of the steel sheet 11.
[0050]
Steel 11 of the chemical composition, by quenching in the hot-pressing method, the mechanical strength, rises above about 1500 MPa. In hot pressing method, the steel sheet 11, since the press-formed in a state of being softened, it is easily molded. Further, the steel sheet 11 may be thin in order to reduce weight, maintain high mechanical strength.
[0051]
Al-based plating layer 12 is formed on one surface (e.g., upper surface) of the steel sheet 11, containing at least aluminum (Al) mass% or more and 85%. The Al-based plating layer 12 is, for example, it is preferably formed by a hot dipping method, the forming method is not limited to hot dipping.
[0052]
Al-based plating layer 12 has only to contain at least aluminum 85% or more as described above, may contain components other than aluminum. Components other than aluminum is not particularly limited, silicon is preferred for the following reasons.
[0053]
Silicon, when hot dipping of a steel sheet 11, an alloy layer of iron and aluminum (hereinafter referred to as Fe-Al alloy layer) is an element having a function of suppressing generation of. If the silicon content of the Al-based plating layer 12 is less than 3%, the Fe-Al alloy layer at the time of hot dipping the steel sheet 11 is grown thick, the plated layer cracking is promoted at the time of processing, possibly corrosion resistance is impaired is there. On the other hand, the silicon content of the Al-based plating layer 12 exceeds 15%, workability and corrosion resistance of the Al-based plating layer 12 is decreased. Hence, silicon content of the Al-based plating layer 12 is preferably 3 to 15%.
[0054]

　Al-based plating layer 12 of the chemical composition, prevention and serves to prevent corrosion of the steel sheet 11, a hot press before the heating due to the scale on the surface of the steel sheet 11 (oxide of iron) is generated the role also be responsible.　
[0055]

　Therefore, by forming the Al-based plating layer 12 on the steel plate 11, the scale removal process, surface cleaning step, can be omitted and the surface treatment process, the productivity of the Al-based plated steel sheet 10 is improved. Also, Al-based plating layer 12 is coated and formed of an organic material, other metal-based material (e.g., Zn-based materials) because of its high melting point than the coating formed by the time of hot press, it is possible to work at elevated temperatures.　
[0056]
A part of the aluminum contained in the Al-based plating layer 12, at the time or hot pressing melting plating, to iron and alloying of the steel sheet 11. Therefore, Al-based plating layer 12 is not necessarily limited to component composition is formed by the constant single layer, in some cases partially containing alloyed layer (alloy layer).
Further, the amount of deposition of the Al-based plating layer 12 to the steel sheet 11, 80 g / m on one surface 2 If it is, the film thickness of the Al-based plating layer 12 of each surface is about 15 [mu] m.
[0057]
　Surface film layer 13 is laminated on the surface of the Al-based plating layer 12 contains at least zinc oxide (ZnO). The surface coating layer 13, for example, aqueous suspension of fine particles of zinc oxide, a roll coater or the like, is formed by being applied to the surface of the Al-based plating layer 12. The surface coating layer 13, hot lubricity during pressing of the Al-based plated steel sheet 10, and has the effect of improving the reactivity with the chemical conversion treatment liquid.
[0058]
Surface film layer 13, in addition to the zinc oxide mentioned above, further contain one or more lubricity enhancing compound. The lubricity enhancing compound is preferably one or more transition metal elements is a compound containing a (third group in the periodic table element belonging to Group 11).
[0059]
Furthermore, the transition metal elements, titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium ( Zr), molybdenum (Mo), tungsten (W), lanthanum (La), and more preferably any one or more of cerium (Ce).
In particular, nickel, titanium, zirconium, manganese, and, lubricity improving effect of a compound containing any one or more of copper is remarkable. Compounds of these elements, oxides, nitrides, sulfides, or phosphate and the like are preferable.
[0060]
The compounds of the transition metal element, but contributes reason to improvement of lubricity at the time of hot pressing is not clear, only with the compound of the transition metal element, since the lubricating property improving effect can not be obtained, and zinc oxide It believed to be combined or synergistic effects of.
[0061]
The essentially responsible for the lubricity improving effect is a zinc oxide, by addition of the compound of the transition metal elements, during hot pressing, the composite oxide and a compound of zinc oxide and the transition metal element reacts There is formed, as a result, lubricity is estimated to be improved.
[0062]
Zinc oxide, the surface film layer 13 containing a compound of the above-mentioned transition metal elements (lubricity enhancing compound), for example, application of a paint containing zinc oxide and lubricity enhancing compound, the baking and drying after coating It is formed on the surface of the Al-based plating layer 12.
[0063]
As a method for coating zinc oxide and lubricity enhancing compound, for example, zinc oxide, a suspension containing the lubricity enhancing compound containing a transition metal element, to produce a coating material by mixing with an organic binder, a method of applying the coating to the surface of the Al-based plating layer 12, it is possible to use a coating method according to powder coating.
[0064]
The lubricity enhancing compound containing a transition metal element described above, for example, nickel sulfate, manganese sulfate, titanium fluoride, zirconium nitrate, or copper sulfate or the like. The organic binder, for example, a polyurethane resin, a polyester resin, it is preferable to use an acrylic resin, or a silane coupling agent or the like.
[0065]
The above lubricity enhancing compounds and organic binder, respectively, is preferably a water-soluble to allow mixing of the suspension containing zinc oxide. Thus, the coating material obtained by mixing the suspension and the organic binder containing zinc oxide and lubricity enhancing compound is applied to the surface of the Al-based plated steel sheet 12.
[0066]
The particle size of the zinc oxide is not particularly limited, a diameter of about 50 ~ 1000 nm is preferable. The particle size of the zinc oxide is the particle size after subjected to heat treatment. Specifically, retaining 5-6 minutes at 900 ° C. in a furnace, it defines the particle size after quenching with mold was observed with SEM or the like.
[0067]
In the surface coating layer 13, the content of lubricity enhancing compound containing a transition metal element is preferably 1 to 40% by mass ratio of zinc oxide. When the content of the lubricating enhancing compounds is less than 1%, the effect of improving the lubricity is not sufficiently obtained at the time of hot press. On the other hand, when the content of the lubricity improver compound exceeds 40%, the adhesion of the surface coating layer 13 after heating is reduced.
[0068]
The content of the organic binder such as a resin component or a silane coupling agent in the surface coating layer 13 (organic compound), by mass ratio of zinc oxide is preferably 5-30%. When the content of the organic binder is less than 5%, the binder effect is insufficient, the coating film before the heating is likely to peel. In order to be able to binder effect stably, the content of the organic binder is more than 10% by mass ratio of zinc oxide is more preferable. When the content of the organic binder exceeds 30%, the occurrence of smell becomes remarkable when heating is not preferable.
[0069]
The present inventors have found that silicon described in Patent Document 2, zirconium, titanium, and inorganic compound layer, an organic compound layer containing at least one phosphorus, or, even compared to those of the composite compound layer, present towards the surface coating layer 13 in the embodiment it is confirmed more that lubricity is high. Therefore, according to the Al-based plated steel sheet 10 of the present embodiment than conventional has good lubricity can be achieved an improvement in moldability and productivity during hot pressing.
[0070]
Surface film layer 13, 0.3 ~ 7g / m zinc terms 2 preferably contains zinc oxide.
[0071]

　Figure 4 is a diagram showing the relationship between the content of zinc oxide in the surface coating layer 13 (the zinc equivalent amount) and the film peeling rate. Decapsulation rate, the amount of zinc was stripped from the surface coating layer 13 by rubbing test, a value obtained by dividing an amount of zinc contained in the surface coating layer 13 prior to rubbing test, is used as an evaluation index of lubricity .　
[0072]
Figure 4 As shown in, and the content of zinc oxide in the surface coating layer 13 is 0.3 ~ 7 g / m 2 If it is, the film peeling rate is 15% or less, lubricity of the surface film layer 13 is a good is there. And the content of zinc oxide in the surface coating layer 13 is 7 g / m 2 by weight, the surface coating layer 13 is thick, the film peeling rate increases rapidly, weldability and coating adhesion is reduced.
[0073]

　Accordingly, in one surface of the surface coating layer 13 of the steel sheet 11, the content of zinc oxide, 0.3 ~ 7 g / m in terms of zinc, based 2 it is desirable. Further, the content of zinc oxide in the surface film layer 13, 0.5 ~ 2 g / m 2 and more desirably, other lubricity during hot pressing, weldability and coating adhesion becomes better.　
[0074]
Zinc oxide, baking and drying process after application of the paint containing lubricity enhancing compounds and organic binder, for example, a method using a hot air furnace, an induction heating furnace, or near-infrared furnace or the like, or a combination of these furnaces it may be a method to use. Depending on the type of organic binder, instead of baking and drying after paint application, ultraviolet, or may be employed curing method using electron beam or the like. In addition, the method of forming the surface coating layer 13 is not limited to the above method, it may be selected from various film forming methods.
[0075]
If you do not use organic binder, a surface coating layer 13, adhesion between the Al-based plating layer 12 before heating is slightly lowered, partially peeled when rubbed with a strong force. Thus, the surface coating layer 13 of Al-based plated steel sheet 10, since exhibit good lubricity during hot pressing to improve formability of Al-based plated steel sheet 10 at the time of hot pressing, also hot corrosion resistance of the Al-based plated steel sheet 10 after pressing is improved.
[0076]
The surface coating layer 13 of Al-based plated steel sheet 10 has the effect of suppressing adhesion to the mold of the Al-based plated steel sheet 10. Even if you Al-based plating layer 12 is pulverized, the surface coating layer 13 containing zinc oxide surface, powder subsequent mold (Al-Fe powder and the like) prevents to adhesion. Thus, the step of removing the Al-Fe alloy powder which is adhesion to the mold is not required, the productivity is improved.
[0077]
Surface coating layer 13, during hot pressing, so also serves as a protective layer to prevent the scratches are generated on the steel plate 11 and / or Al-based plated layer 12, formed of Al-based plated steel sheet 10 is more improves. Further, the surface coating layer 13 has an effect of suppressing deterioration of spot weldability and coating adhesion etc. of the Al-based plated steel sheet 10. The formation of the chemical conversion film to the Al-based plated steel sheet 10, since the corrosion resistance after painting of the Al-based plated steel sheet 10 is significantly improved, thereby reducing the adhesion of the surface coating layer 13. As a result, during rapid pressing of the Al-based plated steel sheet 10, Al-Fe alloy powder was peeled from the Al-based plated steel sheet 10 is suppressed to be adhesion to the mold, thereby further improving productivity.
Incidentally, the adhesion amount of the surface coating layer 13 to the steel sheet 11 (Al-based plating layer 12) of 1 g / m of Zn terms 2 If it is, the thickness of the surface coating layer 13 is about 0.5 [mu] m.
[0078]
　Al-based plated steel sheet 10 of the present embodiment, in a variety of ways, but can be processed and molding is suitable for molding by hot pressing method. The following describes hot pressing method of the Al-based plated steel sheet 10 in this embodiment.
[0079]
In the hot pressing process of the Al-based plated steel sheet 10, firstly, it is softened by heating an Al-based plated steel sheet 10 after blanking. The Al-based plated steel sheet 10 is softened, after press-molded into a desired shape and cooled. Because once softening the Al-based plated steel sheet 10, it is possible to easily subsequent press forming. Thereafter, Al-based plated steel sheet 10 is hardened by heating and cooling, the steel sheet having a high mechanical strength of at least 1500 MPa.
[0080]
As the heating method in the hot pressing method, ordinary electric furnace, radiant tube furnace, or may employ a heating method using infrared rays or the like. When the Al-based plated steel sheet 10 is heated above the melting point of aluminum, Al-based plating layer 12 is molten, aluminum and iron is diffused to each other, an alloy layer of aluminum and iron (Al-Fe alloy layer), or, aluminum, an alloy layer of iron and silicon (Al-Fe-Si alloy layer) is produced. These Al-Fe alloy layer, and, Al-Fe-Si alloy layer has a high melting point, respectively, is about 1150 ° C..
[0081]

　In Al-based plated steel sheet 10, Al-Fe alloy layer, and a compound forming an Al-Fe-Si alloy layer there are a plurality, these compounds are high-temperature heating, or, at prolonged heating, the iron concentration changes to high compound. Desired surface state as the final product of Al-based plated steel sheet 10, in a state alloyed to the surface, and a state not high iron concentration in the alloy layer.　
[0082]

　If aluminum is not alloyed is left, the only remaining portion of the aluminum rapidly corroded easily occurs blister coating film after coating. Conversely, even if too high iron concentration of Al-Fe alloy layer, decreases the corrosion resistance of the Al-Fe alloy layer itself tends to occur blister coating film after coating. This is because the corrosion resistance of the Al-Fe alloy layer is dependent on the aluminum concentration in the alloy layer.　
[0083]
Therefore, in order to ensure the corrosion resistance after painting, there is desired alloying state, the alloying condition is determined by heating conditions and coating weight.
[0084]
In hot pressing method of the present embodiment, setting the average heating rate up to the plate temperature of the Al-based plated steel sheet 10 reaches 10 ° C. lower temperature than the peak metal temperature of from 50 ° C. to 10 ~ 300 ° C. / sec can do. The average heating rate, affects the productivity of the Al-based plated steel sheet 10, general average heating rate in the case of atmospheric heating, about 5 ° C. / sec at a high temperature. The average heating rate of more than 100 ° C. / sec can be achieved by electrical heating or high-frequency induction heating.
[0085]

　When high average heating rate of the above is achieved, the productivity is improved. The average rate of Atsushi Nobori, so influences the composition and thickness of the Al-Fe alloy layer is an important factor in controlling the quality of the product. For Al-based plated steel sheet 10 of the present embodiment, since the heating rate can be increased to 300 ° C. / sec, and the productivity is improved, and can control the quality of products in a wider range.　
[0086]
Hot pressing prior to the heating, based on the principle of hot pressing, it is necessary to heat at the austenite region. The maximum temperature reached in the heating (peak metal temperature) is usually, 900 ~ 950 ° C.. In the hot press method of the present embodiment, the maximum temperature is not particularly limited, preferable because no sufficient hardness is obtained at less than 850 ° C.. Also, Al-based plating layer 12 must be changed to Al-Fe alloy layer is not preferable less than even 850 ° C. In this sense.
[0087]
When the heating temperature exceeds 1000 ° C., alloying excessively proceeds and iron concentration of Al-Fe alloy layer is increased, corrosion resistance after painting is lowered. Corrosion resistance after painting, and heating rate, so also on the amount of deposition of the Al-based plating layer 12, can not be said sweepingly, in consideration of the economical efficiency, heating at temperatures above 1000 ° C. preferably Absent.
[0088]

　As described above, according to the Al-based plated steel sheet 10 according to the first embodiment, the zinc oxide, the surface coating layer 13 containing a lubricity improver compound of the Al-based plating layer 12 containing a transition metal element because it is formed on the surface than conventional earn good lubricity can be achieved an improvement in moldability and productivity during hot pressing.
Further, according to the Al-based plated steel sheet 10 according to the first embodiment, improvement of corrosion resistance after chemical conversion treatability and coating after hot pressing can be realized.　
[0089]
Incidentally, the formation of the surface coating layer 13 chemical conversion treatability are improved (adhesion of the chemical conversion film is improved) reason is not clear. However, chemical conversion treatment reaction, while a reaction that proceeds as a wake etching reaction to the material with acid, zinc oxide contained in the surface coating layer 13 is an amphoteric compound which is soluble in acid. Therefore, zinc oxide contained in the surface coating layer 13 can easily react with the chemical conversion treatment solution is considered as the reason for the chemical conversion treatment improvement.
[0090]
Furthermore, automotive Al-based plated steel sheet 10 of the present embodiment, can be molded into machine parts of various shapes by the application of hot pressing method described above, to be particularly lightweight, request high rigidity and high corrosion resistance it is suitable for parts of production. As the auto parts, for example door impact beams and bumper beams, or include press molding parts such as the center pillar reinforcement.
Figure 2 shows, as an example of the automobile parts is a diagram showing an external view of a center pillar stiffener. As shown in FIG. 2, the center pillar reinforcing member 100 is a molded automotive parts such that the vertically long shape when viewed from the upper end 111 is fixed to the vehicle roof side rail, a lower end 112 is an automobile It is fixed to the bottom of the sill. By manufacturing the center pillar reinforcing member 100 by molding the Al-based plated steel sheet 10 of the present embodiment, it is possible to enhance the collision safety of automobiles.
[0091]
Second Embodiment
　Next, a description of a second embodiment of the present invention. Figure 1B is a diagram showing a layer structure of the Al-based plated steel sheet 20 according to the second embodiment. As shown in FIG. 1B, the Al-based plated steel sheet 20 according to the second embodiment, the steel plate 21, the Al-based plating layer 22 formed on one side (e.g., upper surface) of the steel plate 21, the Al-based plating layer 22 and a formed surface coating layer 23 on the surface.

In FIG. 1B, on one side of the steel sheet 21, but illustrates a case where Al-based plating layer 22 and the surface coating layer 23 is formed, Al-based plating layer on both surfaces of the steel plate 21 22 and the surface coating layer 23 There may be formed.
[0092]
　Steel 21 serves as a substrate of Al-based plated steel sheet 20, the required mechanical properties (tensile strength, yield point, elongation, diaphragm, hardness, impact value, fatigue strength, mechanical such as creep strength having the characteristics) about Do deformation and fracture. The steel plate 21 is, for example, by mass%, of from 0.1 to 0.4% carbon (C), 0.01 ~ 0.6% of silicon (Si), 0.5 ~ 3% of manganese (Mn) 0.01 to 0.1% titanium (Ti), and contain such 0.0001 to 0.1% of boron (B), and containing the remainder of iron (Fe) and unavoidable impurities.
[0093]
　The following describes the role of each element contained in the steel sheet 21. In the following description,% means mass%.　
[0094]

　Carbon is an element for ensuring the mechanical strength of the steel sheet 21. If the carbon content of the steel plate 21 is less than 0.1%, no sufficient mechanical strength can be obtained. On the other hand, when the carbon content of the steel sheet 21 is more than 0.4%, although the hardness of the steel sheet 21 (mechanical strength) is increased, the melting cracking is likely to occur in the steel plate 21. Therefore, the carbon content of the steel sheet 21 is preferably 0.1 to 0.4%.　
[0095]

　Silicon, like carbon, is an element for ensuring the mechanical strength of the steel sheet 21. If the silicon content of the steel sheet 21 is less than 0.01%, the strength improvement effect is not exhibited, sufficient mechanical strength can be obtained. Meanwhile, silicon, because even oxidizable elements, the silicon content of the steel sheet 21 is more than 0.6%, and reduced wettability when performing molten Al plated steel sheet 21, non-plating occurs. Thus, silicon content of the steel plate 21 is preferably 0.01 to 0.6%.　
[0096]

　Manganese increases the hardenability of the steel sheet 21, a reinforcing element for increasing the strength of the steel plate 21. Further, manganese, because it generates the unavoidable impurities in the steel sheet 21 Sulfur (S) with a compound to manganese sulfide (MnS), also serves to prevent hot shortness of the steel plate 21 by sulfur. If the manganese content of the steel sheet 21 is less than 0.5%, its addition effect is not exhibited. On the other hand, when the manganese content of the steel sheet 21 is more than 3%, the residual γ phase of the steel sheet 21 is large and becomes the strength decreases. Therefore, the manganese content of the steel sheet 21 is desirably from 0.5 to 3%.　
[0097]

Titanium is a strength enhancing element, also, is an element for improving the heat resistance of the Al-based plating layer 22. If the titanium content of the steel sheet 21 is less than 0.01%, no strength improving effect or oxidation resistance improving effect is obtained. On the other hand, when the titanium content of the steel sheet 21 is more than 0.1%, carbides and nitrides are generated steel 21 ends up softening, required mechanical strength can not be obtained. Therefore, the titanium content of the steel plate 21 is preferably from 0.01 to 0.1%.　
[0098]

Boron increases the hardenability of the steel sheet 21, which is an element for improving the strength of the steel sheet 21. If the boron content of the steel sheet 21 is less than 0.0001%, the strength improvement effect is not exhibited. On the other hand, when the boron content of the steel sheet 21 is more than 0.1%, inclusions are generated, the fatigue strength of the steel sheet 21 is reduced. Accordingly, the boron content of the steel plate 21 is preferably 0.0001 to 0.1 percent.　
[0099]

Incidentally, the steel sheet 21, the inevitable impurities incorporated during the manufacturing process, may be contained in an amount that does not impair the mechanical properties of the steel sheet 21.　
[0100]

　Steel 21 of the chemical composition, by quenching in the hot-pressing method, the mechanical strength, rises above about 1500 MPa. In hot pressing method, the steel sheet 21, since the press-formed in a state of being softened, it is easily molded. Further, the steel plate 21, be thinned for weight reduction, which maintains high mechanical strength.　
[0101]

　Al-based plating layer 22 is formed on one side of the steel sheet 21 (upper surface) is a plating layer containing at least aluminum (Al) mass% or more and 85%. The Al-based plating layer 22 is, for example, it is preferably formed by a hot dipping method, the forming method is not limited to hot dipping.　
[0102]

　Al-based plating layer 22 has only to contain at least aluminum 85% or more as described above, may also contain components other than aluminum. Components other than aluminum is not particularly limited, silicon is preferred for the following reasons.　
[0103]
Silicon, when hot-dip plating of the steel sheet 21, an alloy layer of iron and aluminum (hereinafter referred to as Fe-Al alloy layer) is an element having a function of suppressing generation of. If the silicon content of the Al-based plating layer 22 is less than 3%, the Fe-Al alloy layer at the time of hot-dip plating of the steel sheet 21 is grown thick, the plated layer cracking is promoted at the time of processing, possibly corrosion resistance is impaired is there. On the other hand, the silicon content of the Al-based plating layer 22 exceeds 15%, workability and corrosion resistance of the Al-based plating layer 22 is decreased. Hence, silicon content of the Al-based plated layer 22 is desirably 3-15%.
[0104]

　Al-based plating layer 22 of the chemical composition, prevention and serves to prevent corrosion of the steel sheet 21, a hot press before the heating due to the scale on the surface of the steel sheet 21 (oxide of iron) is generated the role also be responsible.　
[0105]

　Therefore, by forming the Al-based plating layer 22 on the steel plate 21, the scale removal process, surface cleaning step, can be omitted and the surface treatment process, the productivity of the Al-based plated steel sheet 20 is improved. Also, Al-based plating layer 22 is coated and formed of an organic material, other metal-based material (e.g., Zn-based materials) because of its high melting point than the coating formed by the time of hot press, it is possible to work at elevated temperatures.　
[0106]

　A part of the aluminum contained in the Al-based plating layer 22, at the time or hot pressing melting plating, to iron and alloying of the steel sheet 21. Therefore, Al-based plating layer 22 is not necessarily limited to component is formed in a constant single layer, in some cases partially containing alloyed layer (alloy layer).
　Further, the amount of deposition of the Al-based plating layer 22 to the steel sheet 21, 80 g / m on one surface 2 If it is, the film thickness of the Al-based plating layer 22 of each surface is about 15 [mu] m.　
[0107]
　Surface film layer 23 is laminated on the surface of the Al-based plating layer 22, a surface coating layer containing at least zinc oxide (ZnO). For example, aqueous suspension of fine particles of zinc oxide, a roll coater or the like, by being applied to the surface of the Al-based plating layer 22, the surface coating layer 23 on the surface of the Al-based plating layer 22 is formed. The surface coating layer 23, lubricity during hot pressing of the Al-based plated steel sheet 20, and has the effect of improving the reactivity with the chemical conversion treatment liquid.
[0108]
　Surface film layer 23, in addition to the zinc oxide mentioned above, further contain one or more lubricity enhancing compound. In the first embodiment, using a compound containing a transition metal element as a lubricity enhancing compound, in the second embodiment, as lubricity enhancing compound, in addition to lubricity improving effect, Al-based plated steel sheet during heating with improved effect of Atsushi Nobori characteristics of 20 (the effect of improving heating rate), one or more typical elements (the group 1 and group 2 and elements belonging to group 12 - group 18 in the periodic table) the compound containing used.

In particular, typical elements described above, magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), phosphorus (P), tin (Sn), and any one or more of germanium (Ge) it is preferable that.
Compounds of these typical element is desirably an oxide, for example, magnesia, or calcia, and the like are preferable. These compounds have a high emissivity is believed that the heat in the heating furnace efficiently absorb. In particular, in a heating furnace, using a heating element which emits far-infrared rays, Atsushi Nobori characteristics are remarkably improved. The reason is, the oxide containing zinc oxide, is estimated to be because have high emissivity for wavelengths in the far infrared range.　
[0109]
Zinc oxide, the surface film layer 23 comprising a compound of the above-mentioned typical element (lubricity enhancing compound), for example, application of a paint containing zinc oxide and lubricity enhancing compound, the baking and drying after coating, Al It is formed on the surface of the system plating layer 22.
[0110]

As a method for coating zinc oxide and lubricity enhancing compound, for example, zinc oxide, a suspension containing the lubricity enhancing compounds containing group elements, to produce a coating material by mixing with an organic binder, this a method of applying paint to the surface of the Al-based plating layer 22, it is possible to use a coating method according to powder coating.　
[0111]
The lubricity enhancing compound containing a typical element of the, for example, magnesia (MgO), calcia (CaO), or forsterite (Mg 2 SiO 4 ) or the like is preferably used. As the organic binder, for example, a polyurethane resin, a polyester resin, it is preferable to use an acrylic resin, or a silane coupling agent or the like. The above lubricity enhancing compounds and organic binder, respectively, is preferably a water-soluble to allow mixing of the suspension containing zinc oxide. Thus, the coating material obtained by mixing the suspension and the organic binder containing zinc oxide and lubricity enhancing compound is applied to the surface of the Al-based plated steel sheet 22.
[0112]

The particle size of the zinc oxide is not particularly limited, a diameter of about 50 ~ 1000 nm is preferable. The particle size of the zinc oxide is the particle size after subjected to heat treatment. Specifically, retaining 5-6 minutes at 900 ° C. in a furnace, it defines the particle size after quenching with mold was observed with SEM or the like.　
[0113]

　The particle size of the lubricity enhancing compound containing a typical element in the surface coating layer 23 is also not particularly limited, zinc comparable oxidation is desired.　
[0114]

　In the surface coating layer 23, the content of lubricity enhancing compound containing a typical element, preferably 5-30% by mass ratio of zinc oxide. When the content of the lubricating enhancing compounds is less than 5%, the improvement effect (improvement rate of temperature increase) of Atsushi Nobori characteristics in the heating furnace can not be obtained sufficiently. On the other hand, when the content of the lubricity improver compound exceeds 30%, it is easy reactivity with the chemical conversion solution after heating is impaired.　
[0115]

　The content of the organic binder such as a resin component or a silane coupling agent in the surface coating layer 23 (organic compound) is desirably 5-30% by mass ratio of zinc oxide. When the content of the organic binder is less than 5%, the binder effect is not obtained sufficiently, it is easy to take the coating before heating. In order to be able to binder effect stably, the content of the organic binder is more preferably 10% or more by mass ratio of zinc oxide. On the other hand, if the content of the organic binder exceeds 30%, the odor generation during heating becomes significant, which is not preferable.　
[0116]
The present inventors have found that silicon described in Patent Document 2, zirconium, titanium, and inorganic compound layer, an organic compound layer containing at least one phosphorus, or, even compared to those of the composite compound layer, present towards the surface coating layer 23 in the embodiment it is confirmed more that lubricity is high. Therefore, according to the Al-based plated steel sheet 20 of the present embodiment than conventional has good lubricity can be achieved an improvement in moldability and productivity during hot pressing.
[0117]

　Surface film layer 23, 0.3 ~ 7g / m zinc terms 2 preferably contains zinc oxide.　
[0118]

　And the content of zinc oxide in the surface film layer 23, in terms of zinc, based 0.3 g / m 2 If it is above, lubricity improving effect appears. On the other hand, the content of zinc oxide in the surface film layer 23, 7 g / m in terms of zinc, based 2 exceeds, becomes thick Al-based plating layer 22 and the surface coating layer 23, weldability and coating adhesion is reduced.　
[0119]

　Accordingly, the content of zinc oxide in the surface film layer 23, the surface coating layer 23 of one side, 0.3 ~ 7 g / m in terms of zinc, based 2 is desirable. Ensuring lubrication during hot pressing, From the standpoint of ensuring good weldability and coating adhesion, and the content of zinc oxide in the surface film layer 13 is 0.5 ~ 2 g / m 2 , especially preferred it is.　
[0120]

　Zinc oxide, baking and drying process after application of the paint containing lubricity enhancing compounds and organic binder, for example, a method using a hot air furnace, an induction heating furnace, or near-infrared furnace or the like, or a combination of these furnaces it may be a method to use. Depending on the type of organic binder, instead of baking and drying after paint application, ultraviolet, or may be employed curing method using electron beam or the like. In addition, the method of forming the surface coating layer 23 is not limited to the above method, it may be selected from various film forming methods.　
[0121]

　If you do not use organic binder, a surface coating layer 23, adhesion between the Al-based plating layer 22 before heating is slightly lowered, partially peeled when rubbed with a strong force. Thus, the surface coating layer 23 of Al-based plated steel sheet 20, since exhibit good lubricity during hot pressing to improve formability of Al-based plated steel sheet 20 at the time of hot pressing, also hot corrosion resistance of the Al-based plated steel sheet 20 after pressing is improved.　
[0122]

　The surface coating layer 23 of Al-based plated steel sheet 20 has the effect of suppressing adhesion to the mold of the Al-based plated steel sheet 20. Even if you Al-based plating layer 22 is pulverized, the surface coating layer 23 containing zinc oxide surface, powder subsequent mold (Al-Fe powder and the like) prevents to adhesion. Thus, the step of removing the Al-Fe alloy powder which is adhesion to the mold is not required, the productivity is improved.　
[0123]

　Surface coating layer 23, during hot pressing, since scratches in the steel plate 21 and / or Al-based plated layer 22 also serves as a protective layer to prevent the occurrence of more formability of Al-based plated steel sheet 20 improves. Further, the surface coating layer 23 has an effect of suppressing deterioration of spot weldability and coating adhesion etc. of the Al-based plated steel sheet 20. The formation of the chemical conversion film to the Al-based plated steel sheet 20, since the corrosion resistance after painting of the Al-based plated steel sheet 20 is significantly improved, thereby reducing the adhesion of the surface coating layer 23. As a result, during rapid pressing of the Al-based plated steel sheet 20, Al-Fe alloy powder was peeled from the Al-based plated steel sheet 20 is suppressed to be adhesion to the mold, thereby further improving productivity.
　Incidentally, the adhesion amount of the surface coating layer 23 to the steel sheet 21 (Al-based plating layer 22) of 1 g / m of Zn terms 2 If it is, the thickness of the surface coating layer 23 is about 0.5 [mu] m.　
[0124]
　Al-based plated steel sheet 20 of the present embodiment, in a variety of ways, but can be processed and molding is suitable for molding by hot pressing method. The following describes hot pressing method of the Al-based plated steel sheet 20 in this embodiment.
[0125]

　In the hot pressing process of the Al-based plated steel sheet 20, firstly, it is softened by heating an Al-based plated steel sheet 20 after blanking. The softened Al-based plated steel sheet 20 was, after press-molded into a desired shape and cooled. Because once softening the Al-based plated steel sheet 20, it is possible to easily subsequent press forming. Al-based plated steel sheet 20 is hardened by heating and cooling, the steel sheet having a high mechanical strength of at least about 1500 MPa.　
[0126]

　As the heating method in the hot pressing method, ordinary electric furnace, radiant tube furnace, or may employ a heating method using infrared rays or the like. When the Al-based plated steel sheet 20 is heated above the melting point of aluminum, Al-based plating layer 22 is molten, aluminum and iron is diffused to each other, an alloy layer of aluminum and iron (Al-Fe alloy layer), or, aluminum, an alloy layer of iron and silicon (Al-Fe-Si alloy layer) is produced. These Al-Fe alloy layer, and, Al-Fe-Si alloy layer has a high melting point, respectively, is about 1150 ° C..　
[0127]

　In Al-based plated steel sheet 20, Al-Fe alloy layer, and a compound forming an Al-Fe-Si alloy layer there are a plurality, these compounds are high-temperature heating, or, at prolonged heating, the iron concentration changes to high compound. Desired surface state as the final product of Al-based plated steel sheet 20, in a state alloyed to the surface, and a state not high iron concentration in the alloy layer.　
[0128]

　If aluminum is not alloyed is left, the only remaining portion of the aluminum rapidly corroded easily occurs blister coating film after coating. Conversely, even if too high concentration of iron in the alloy layer in corrosion resistance of the alloy layer itself is lowered, it tends to occur blister coating film after coating. This is because the corrosion resistance of the alloy layer depends on the aluminum concentration in the alloy layer.　
[0129]

　Therefore, in order to ensure the corrosion resistance after painting, there is desired alloying state, the alloying condition is determined by heating conditions and coating weight.　
[0130]

　In hot pressing method of the present embodiment, setting the average heating rate up to the plate temperature of the Al-based plated steel sheet 20 reaches 10 ° C. lower temperature than the peak metal temperature of from 50 ° C. to 10 ~ 300 ° C. / sec can do. The average heating rate, affects the productivity of the Al-based plated steel sheet 20, general average heating rate in the case of atmospheric heating, about 5 ° C. / sec about at high temperatures. The average heating rate of more than 100 ° C. / sec can be achieved by electrical heating or high-frequency induction heating.　
[0131]
When high average heating rate of the above is achieved, the productivity is improved. The average rate of Atsushi Nobori, so influences the composition and thickness of the alloy layer is an important factor in controlling the quality of the product. For Al-based plated steel sheet 20 of the present embodiment, since the heating rate can be increased to 300 ° C. / sec, and the productivity is improved, and can control the quality of products in a wider range.

claims

And the steel sheet;
　formed on one surface or both surfaces of the steel sheet, and Al-based plating layer containing at least Al mass% or more and 85%;
　laminated on the surface of the Al-based plating layer, improved ZnO and one or more lubricious ; and a surface coating layer containing the compound
Al-based plated steel sheet, characterized in that it comprises a.
[Requested item 2]
　The lubricity enhancing compounds, Al-based plated steel sheet according to claim 1, characterized in that a compound containing one or more transition metal elements.
[Requested item 3]
　Wherein the transition metal element, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Mo, W, La, and, to claim 2, characterized in that any one or more of Ce Al-based plated steel sheet according.
[Requested item 4]
　In the surface coating layer, Al-based plated steel sheet according to claim 2, wherein the mass ratio relative to the ZnO of the lubricity enhancing compound containing the transition metal element is 1 to 40%.
[Requested item 5]
　The lubricity enhancing compounds, Al-based plated steel sheet according to claim 1, characterized in that a compound containing one or more typical elements.
[Requested item 6]
　The typical element is, Mg, Ca, Sr, Ba, P, Sn, and, Al-based plated steel sheet according to claim 5, characterized in that any one or more of Ge.
[Requested item 7]
　In the surface coating layer, Al-based plated steel sheet according to claim 5, wherein the mass ratio relative to the ZnO of the lubricity enhancing compound containing the typical element is 5 to 30%.
[Requested item 8]
　The surface coating layer, 0.3 ~ 7g / m in Zn terms 2 Al-based plated steel sheet according to any one of claims 1 to 7, characterized in that it contains the ZnO of.
[Requested item 9]
　The surface coating layer, Al-based plated steel sheet according to any one of claims 1 to 8, characterized in that the mass ratio relative to the ZnO is further contain an organic compound of 5-30%.
[Requested item 10]
　The Al-based plated steel sheet according to any one of claims 1 to 9, and heated after blanking, then hot pressing method of the Al-based plated steel sheet, characterized in that the press-molding.
[Requested item 11]
　In heating before the press molding, the average heating rate up to the plate temperature of the Al-based plated steel sheet to reach the peak metal temperature of from 10 ° C. lower temperature from 50 ° C. is a 10 ~ 300 ° C. / sec hot pressing method of Al-based plated steel sheet according to claim 10, wherein.
[Requested item 12]
　Hot pressing method of Al-based plated steel sheet according to claim 11, characterized in that the electrical heating or induction heating heating before the press forming.
[Requested item 13]
　Automobile parts, characterized in that it is manufactured by hot pressing method of Al-based plated steel sheet according to any one of claims 10-12.