Invention name: Hot stamp molded article
Technical field
[0001]
　The present invention relates to a hot stamped article.
　The present application claims priority based on Japanese Patent Application No. 2019-157205 filed in Japan on August 29, 2019, the contents of which are incorporated herein by reference.
Background technology
[0002]
　In recent years, it has been required to curb the consumption of chemical fuels in order to protect the environment and prevent global warming. Such a request is no exception to, for example, automobiles, which are indispensable for daily life and activities as a means of transportation. In response to such demands, automobiles are being considered for improving fuel efficiency by reducing the weight of the vehicle body. Since most of the structure of an automobile is made of iron, especially a steel plate, thinning the steel plate to reduce the weight has a great effect on reducing the weight of the vehicle body. However, if the thickness of the steel sheet is simply reduced to reduce the weight of the steel sheet, there is a concern that the strength of the structure will decrease and the safety will decrease. Therefore, in order to reduce the thickness of the steel sheet, it is required to increase the mechanical strength of the steel sheet used so as not to reduce the strength of the structure.
　Therefore, research and development are being carried out on a steel sheet that can maintain or increase its mechanical strength even if it is thinner than the previously used steel sheet by increasing the mechanical strength of the steel sheet. Requests for such steel sheets are made not only in the automobile manufacturing industry but also in various manufacturing industries.
[0003]
　In general, a material having high mechanical strength tends to have low shape freezing property in molding processing such as bending, and when processing into a complicated shape, the processing itself becomes difficult. As one of the means for solving this problem of moldability, there is a so-called "hot pressing method (hot stamping method, high temperature pressing method, diquenching method)". In this hot pressing method, the material to be molded is once heated to a high temperature, and the material softened by heating is pressed and molded, or then cooled at the same time as molding.
[0004]
　According to this hot pressing method, the material is once heated to a high temperature to be softened and pressed in a state where the material is softened, so that the material can be easily pressed. Therefore, by this hot press working, a press-molded product having both good shape freezing property and high mechanical strength can be obtained. In particular, when the material is steel, the mechanical strength of the press-molded product can be increased by the quenching effect due to cooling after molding.
[0005]
　However, when this hot pressing method is applied to a steel sheet, for example, by heating to a high temperature of 800 ° C. or higher, iron or the like on the surface is oxidized to generate scale (oxide). Therefore, after hot pressing, a step of removing this scale (descaling step) is required, and the productivity is lowered. Further, for a member or the like that requires corrosion resistance, since it is necessary to apply a rust preventive treatment or a metal coating to the surface of the member after processing, a surface cleaning step and a surface treatment step are required, which also reduces productivity.
[0006]
　As an example of a method for suppressing such a decrease in productivity, it is considered to improve the corrosion resistance and omit the descaling step by applying a coating such as plating to the steel sheet before hot stamping.
[0007]
　As such a plated steel material, for example, in Patent Document 1, an Al—Zn-based alloy plating layer containing Al: 20 to 95% by mass, Ca + Mg: 0.01 to 10% by mass, and Si is provided on the surface of a steel sheet. A plated steel sheet for hot pressing, which is characterized by having, is disclosed. According to Patent Document 1, scale formation is suppressed during heating before hot pressing, plating does not adhere to the die during hot pressing, and the obtained hot pressed member has a good appearance. It is disclosed that it has excellent coating adhesion and corrosion resistance.
[0008]
　Further, Patent Document 2 discloses a plated steel material in which a plating layer containing an Al—Fe alloy layer and a Zn—Mg—Al alloy layer is provided on the surface of the steel material, and the corrosion resistance is dramatically improved.
[0009]
　Members obtained by hot stamping plated steel materials as described above are often applied to automobile parts, and when applied as automobile parts, the members are generally subjected to chemical conversion treatment. However, in Patent Document 1 and Patent Document 2, no studies have been made on the characteristics when the chemical conversion treatment film is formed.
　As a result of studies by the present inventors, even if a member obtained by hot stamping a steel sheet having a plating layer containing Al or Zn is subjected to zinc phosphate treatment, which is a general chemical conversion treatment for automobiles, It was found that the zinc phosphate film is difficult to form, or even if it is formed, the adhesion of the coating film when an electrodeposition coating film or the like is formed on the surface may not be sufficient.
[0010]
　Patent Document 3 discloses a method of treating the surface of a zinc-aluminum-magnesium alloy plated steel sheet with a metal surface treatment agent. In Patent Document 3, by containing a fluorine compound in the chemical conversion treatment liquid, a reaction layer containing fluorides of Al and Mg is formed on the surface of the plating layer of the plated steel plate by the chemical conversion treatment, and the chemical conversion film and the surface of the plating layer adhere to each other. It is disclosed that the power can be further enhanced.
[0011]
　However, Patent Document 3 does not study the adhesion of the coating film when an electrodeposition coating film or the like is formed on the chemical conversion coating film.
Prior art literature
Patent documents
[0012]
Patent Document 1: Japanese Patent Application Laid-Open No. 2012-112010
Patent Document 2: Japanese Patent Application Laid-Open No. 2017-66459
Patent Document 3: Japanese Patent Application Laid-Open No. 2016-89232
Outline of the invention
Problems to be solved by the invention
[0013]
　The present invention has been made in view of the above problems. An object of the present invention is to provide a hot stamp molded product having a chemical conversion-treated film having suppressed scale and excellent adhesion to a coating film.
Means to solve problems
[0014]
　By controlling the composition balance of the plating layer of the molten Zn-Al-Mg plated steel sheet and the conditions at the time of manufacturing, the present inventions have a hot chemical conversion coating film which suppresses scale and has excellent coating adhesion. It was found that a stamped product can be obtained.
　The present invention has been completed based on the above findings, and the gist thereof is as follows.
[0015]
(1) The hot stamp molded body according to one aspect of the present invention includes a base material made of steel, a plating layer formed on the surface of the base material, and a chemical conversion treatment film formed on the surface of the plating layer. The chemical composition of the plating layer is, in mass%, Al: 20.00 to 45.00%, Fe: 10.00 to 45.00%, Mg: 4.50 to 15.00%, Si: 0.10 to 3.00%, Ca: 0.05 to 3.00%, Sb: 0 to 0.50%, Pb: 0 to 0.50%, Cu: 0 to 1.00%, Sn: 0 ~ 1.00%, Ti: 0 to 1.00%, Sr: 0 to 0.50%, Cr: 0 to 1.00%, Ni: 0 to 1.00%, Mn: 0 to 1.00% , The balance is Zn and impurities, and the chemical conversion coating film contains Mg: 5.0 to 50.0% and Ca: 0.5 to 5.0% in mass%. The one-sided adhesion amount of the chemical conversion treatment film is 0.1 to 10.0 g / m 2 .
(2) In the hot stamp molded product according to (1) above, the chemical composition of the plating layer is mass%, Al: 25.00 to 35.00%, Mg: 6.00 to 10.00%. , 1 or 2 may be contained.
(3) In the hot stamp molded product according to the above (1) or (2), the amount of the chemical conversion-treated film adhered to one side thereof may be 1.5 to 8.0 g / m 2 .
The invention's effect
[0016]
　According to the above aspect of the present invention, it is possible to provide a hot stamp molded product having a chemical conversion treatment film having suppressed scale and excellent coating film adhesion.
A brief description of the drawing
[0017]
FIG. 1 is a schematic view showing a hot stamp molded body according to the present embodiment.
FIG. 2 is a diagram showing an example of the structure of a chemical conversion-treated film of a hot stamped molded product according to the present embodiment.
[Fig. 3] Example No. It is a figure which shows an example of the structure of the chemical conversion treatment film of the hot stamping compact of 12 (comparative example).
Embodiment for carrying out the invention
[0018]
　A hot stamped body according to an embodiment of the present invention (a hot stamped body according to the present embodiment) will be described with reference to the drawings.
　With reference to FIG. 1, the hot stamp molded body 1 according to the present embodiment has a base material 2 made of steel, a plating layer 3 formed on the surface of the base material 2, and a chemical conversion formed on the surface of the plating layer 3. A treatment film 4 is provided. In FIG. 1, the plating layer 3 and the chemical conversion treatment film 4 are formed on only one side of the base material 2, but may be formed on both sides.
[0019]

　The base material 2 is made of steel. The base material 2 is, for example, a hot stamping member obtained by hot stamping a steel plate. Therefore, although it has a plate shape in FIG. 1, the shape is not limited.
　Further, in the hot stamp molded body 1 according to the present embodiment, the plating layer 3 and the chemical conversion treatment film 4 are important, and the chemical composition and the like of the base material 2 are not particularly limited. For the base material 2, the steel to be subjected to plating, hot stamping, and chemical conversion treatment may be determined according to the product to be applied, the required strength, the plate thickness, and the like. For example, as the base material, a hot-rolled steel sheet described in JIS G3193: 2008 or a cold-rolled steel sheet described in JIS G3141: 2017 can be used.
[0020]

[Chemical composition]
　Hereinafter,% of the chemical composition of the plating layer and the chemical conversion treatment film is mass% unless otherwise specified.
[0021]
Al: 20.00 to 45.00%,
　Al is an essential element for improving the corrosion resistance of the plating layer 3. Further, when the Al content is less than 20.00%, Ca and Al are mainly used as a source of Ca to the chemical conversion treatment layer while suppressing evaporation of Zn and Mg during heating of the hot stamp. Intermetallic compounds are not sufficiently formed on the surface of the plating layer. As a result, the scale of the chemical conversion treatment film 4 formed on the plating layer 3 becomes large. Therefore, the Al content is set to 20.00% or more. It is preferably 25.00% or more.
　On the other hand, even if the Al content exceeds 45.00%, it becomes difficult to form an intermetallic compound mainly composed of Ca and Al on the surface of the plating layer 3 during heating of the hot stamp. As a result, the scale of the chemical conversion treatment film 4 becomes large. Therefore, the Al content is set to 45.00% or less. It is preferably 35.00% or less.
[0022]
Fe: When the plated steel sheet is heated during hot stamping of 10.00 to 45.00%
　, Fe diffuses from the base material 2 to the plating layer 3, so that the plating layer 3 of the hot stamping compact 1 always contains Fe. ..
　When the Fe content is less than 10.0%, the spot weldability and the weldability tend to deteriorate, so the Fe content is set to 10.00% or more.
　On the other hand, if the Fe content is too high, the corrosion resistance tends to deteriorate, so the Fe content is set to 45.00% or less.
[0023]
Mg: 4.50 to 15.00%
　Mg is an element that contributes to the improvement of the corrosion resistance of the plating layer 3. Further, Mg has an effect of suppressing LME cracking because it binds to the Zn component in the plating layer 3 to prevent the generation of liquid phase Zn when the hot stamp is heated. Further, in the hot stamp molded body 1 according to the present embodiment, Mg is an element that diffuses into the chemical conversion treatment film 4 and enhances the adhesion to the coating film. In order to obtain these effects, the Mg content is set to 4.50% or more. When the Mg content is less than 4.50%, the adhesion to the coating film is lowered. The Mg content is preferably 6.0% or more.
　On the other hand, when the Mg content exceeds 15.00%, sacrificial anticorrosion works excessively, and the corrosion resistance of the plating layer 3 tends to decrease. Further, a large amount of Mg-based intermetallic compounds that reduce the chemical conversion treatment property are formed in the plating layer 3, and as a result, the scale of the chemical conversion treatment film 4 becomes large and the coating film adhesion deteriorates. Therefore, the Mg content is set to 15.00% or less. It is preferably 10.00% or less.
[0024]
Si: 0.10 to 3.00%
　Si is an element that forms a compound together with Mg and contributes to the improvement of corrosion resistance. Further, Si suppresses the formation of an excessively thick alloy layer formed between the surface of the steel sheet and the plating layer when forming the plating layer on the steel sheet, and the adhesion between the steel sheet and the plating layer is suppressed. It is also an element that has the effect of increasing the plating. If the Si content is less than 0.10%, these effects cannot be sufficiently obtained. Therefore, the Si content is set to 0.10% or more.
　On the other hand, when the Si content exceeds 3.00%, Mg 2 Si, Mg 2 Ca, or (Mg, Ca) 2 Si is formed, and the Mg content and Ca content contained in the chemical conversion coating film 4 are formed. Is insufficient, and the adhesion of the coating film is lowered. Further, if the Si phase is excessively generated, the chipping resistance and the seizure resistance are lowered. Therefore, the Si content is set to 3.00% or less.
[0025]
Ca: 0.05 to 3.00%
　In the hot stamp molded body 1 according to the present embodiment, Ca is an element that diffuses into the chemical conversion treatment film 4 and enhances the adhesion to the coating film. If the Ca content is less than 0.05%, the scale of the chemical conversion treatment film 4 becomes large. Therefore, the Ca content is set to 0.05% or more.
　On the other hand, when the Ca content exceeds 3.00%, an intermetallic compound containing Ca as a main component, which lowers the chemical conversion treatment property, is formed, so that the Mg content and Ca content of the chemical conversion treatment film are insufficient and the Ca content is insufficient. The scale becomes large and the adhesion to the coating film decreases. Therefore, the Ca content is set to 3.00% or less.
[0026]
　The plating layer 3 of the hot stamp molded body 1 according to the present embodiment basically contains the above-mentioned elements, and the balance is made of Zn and impurities.
　However, the plating layer 3 may contain Sb, Pb, Cu, Sn, Ti, Sr, Cr, Ni, and Mn in the following range in addition to the above elements. Since these elements do not necessarily have to be contained, the lower limit is 0%. The total content of these elements is preferably 5.00% or less.
[0027]
Sb: 0 to 0.50%
Pb: 0 to 0.50%
Cu: 0 to 1.00%
Sn: 0 to 1.00%
Ti: 0 to 1.00%
　Sb, Pb, Cu, Sn and Ti are , It is replaced with Zn in the plating layer 3 and forms a solid solution in the MgZn 2 phase , but if it is within a predetermined content range, it does not adversely affect the characteristics of the hot stamp molded body 1. Therefore, these elements may be contained in the plating layer 3. However, when the content of each element is excessive, oxides of these elements are precipitated when the hot stamp is heated, and the surface properties of the hot stamp molded product 1 tend to deteriorate and the chemical conversion treatment property tends to deteriorate. .. Further, when the contents of Pb and Sn are excessive, the weldability and the LME resistance are also deteriorated.
　Therefore, the contents of Sb and Pb are 0.50% or less, respectively, and the contents of Cu, Sn, and Ti are 1.00% or less, respectively. The content of Sb and Pb is preferably 0.20% or less. The content of Cu, Sn and Ti is preferably 0.80% or less, more preferably 0.50% or less.
[0028]
Sr: 0 to 0.50%
　Sr is an element effective for suppressing the formation of top dross formed on the plating bath during production. Further, Sr is an element that suppresses color change of the plated steel sheet after the heat treatment because it suppresses atmospheric oxidation during the heat treatment of the hot stamp. Therefore, Sr may be contained. In order to obtain the above effects, the Sr content is preferably 0.05% or more.
　On the other hand, when the content of Sr is excessive, the swelling width of the coating film and the flow rust are adversely affected in the corrosion test. Therefore, the Sr content is set to 0.50% or less. The Sr content is preferably 0.30% or less, more preferably 0.10% or less.
[0029]
Cr: 0 to 1.00%
Ni: 0 to 1.00%
Mn: 0 to 1.00%
　In a plated steel sheet, Cr, Ni and Mn are concentrated near the interface between the plating layer and the base material and plated. It is an element that has the effect of eliminating spangles on the layer surface. Therefore, one or more selected from Cr, Ni and Mn may be contained in the plating layer 3. When these effects are obtained, the contents of Cr, Ni and Mn are preferably 0.01% or more, respectively.
　On the other hand, when the content of these elements is excessive, the swelling width of the coating film and the flow rust increase, and the corrosion resistance tends to deteriorate. Therefore, the contents of Cr, Ni and Mn are set to 1.00% or less, respectively. The contents of Cr, Ni and Mn are preferably 0.50% or less, more preferably 0.10% or less, respectively.
[0030]
　The average composition of the plating layer is measured by melting and peeling the plating layer and then analyzing the content of elements contained in the peeled plating layer by inductively coupled plasma atomic emission (ICP) analysis. The peeling of the plating layer may be performed, for example, by immersing the plating layer in 10% hydrochloric acid containing an inhibitor that suppresses corrosion of the base iron (pickling suppression inhibitor: manufactured by Asahi Chemical Co., Ltd.), and determining that the dissolution is completed when the foaming stops. ..
[0031]
　The structure of the plating layer is not limited, but includes, for example, an Fe—Al phase, a Zn—Mg phase, and a Zn—Al—Mg phase. The amount of the plating layer adhered is not limited, but is preferably 10 to 120 g / m 2 . The amount of adhesion of the plating layer can be determined from the change in weight before and after melting the plating layer at room temperature by the above method.
[0032]

[Consists of zinc phosphate crystals containing Mg: 5.0 to 50.0% and Ca: 0.5 to 5.0% by mass]
　Usually, it has a plating layer containing Al. An oxide mainly composed of Al 2 O 3 is formed on the surface (surface of the plating layer) of the hot stamped molded product obtained by hot stamping the steel material. Al 2 O 3 formed on the surface of the plating layer hinders the formation of a chemical conversion treatment film. The ratio of plating increases.
　On the other hand, in the hot stamp molded body according to the present embodiment, by plating by a method as described later, an oxide mainly containing Ca and Mg is formed on the surface of the plated steel material after hot stamping to be subjected to chemical conversion treatment. A film is formed. When this steel material is subjected to zinc phosphate treatment (chemical conversion treatment), Mg and Ca diffuse into the chemical conversion treatment film, and by mass%, Mg: 5.0 to 50.0% and Ca: 0.5 to 5 A chemical conversion-treated film 4 composed of zinc phosphate crystals containing 0.0% is formed. FIG. 2 shows a representative microstructure photograph of the chemical conversion-treated film 4 of the hot stamp molded body 1 according to the present embodiment. The chemical conversion-treated film 4 is composed of zinc phosphate crystals 11 containing Mg: 5.0 to 50.0% and Ca: 0.5 to 5.0%, and the zinc phosphate crystals 11 have a crystal grain size. It is scaly with a major axis of 10 μm or less and a minor axis of 5 μm or less. Further, when such zinc phosphate crystals 11 are formed, the ratio of scale is 10% or less. Further, since the chemical conversion-treated film containing Mg itself has excellent corrosion resistance, it contributes to the improvement of post-coating adhesion (coating film adhesion) as compared with the chemical conversion-treated film containing no Mg.
　If the oxide film of Mg and Ca is not sufficiently formed on the surface of the steel material to be subjected to the chemical conversion treatment, Al oxide is formed and the scale of the chemical conversion treatment film 4 becomes large. If the content of Mg and Ca in the chemical conversion-treated film is low, the corrosion resistance of the chemical conversion-treated film is lowered, so that the adhesion of the coating film is lowered.
　On the other hand, if the content of Mg and Ca is high, the corrosion resistance of the chemical conversion coating film is rather lowered, so that the adhesion of the coating film is lowered.
　Depending on the hot stamping conditions and the thickness of the plating layer, Fe diffused into the plating layer by alloying may be present in the chemical conversion treatment film of zinc phosphate crystals.
[0033]
　The chemical composition of the chemical conversion coating is such that the plating layer is not dissolved and only the chemical conversion coating is dissolved, for example, 20% chromium acid is used to dissolve the solution, and the solution in which the chemical conversion coating is dissolved is analyzed by ICP, and the average of the chemical conversion coating is averaged. Obtained by measuring the composition. Alternatively, it can be measured by preparing a calibration curve in advance and quantitatively analyzing it with fluorescent X-rays.
[0034]
[One-sided adhesion amount is 0.1 to 10 g / m 2 ] When
　the one-sided adhesion amount of the chemical conversion treatment film 4 is less than 0.1 g / m 2 , the coating film adhesion (when a coating film is formed on the surface of the chemical conversion treatment film). The effect of improving (adhesion) is not sufficiently obtained. On the other hand, if the amount of adhesion on one side exceeds 10 g / m 2 , cracks are likely to occur in the chemical conversion-treated film when it is subjected to bending or the like, which causes peeling of the coating film. Therefore, the amount of adhesion on one side is set to 0.1 to 10 g / m 2 . Preferably, it is 1.5 to 8.0 g / m 2 .
[0035]
　When determining the amount of adhesion on one side by the method of dissolving, seal the opposite surface and end surface with tape other than the surface to be measured, and immerse in the solution to obtain a release liquid of only the measurement surface before and after dissolution. It can be obtained from the change in weight.
　When measuring with fluorescent X-rays, the amount of adhesion on only one side is required.
[0036]
　In the hot stamp molded body 1 according to the present embodiment, an oxide film may be further provided between the plating layer 3 and the chemical conversion treatment film 4. This oxide film is made of, for example, calcium oxide or magnesium oxide.
[0037]

　The hot stamp molded product according to the present embodiment can obtain the effect as long as it has the above-mentioned characteristics regardless of the manufacturing method. However, a production method including the following steps is preferable because stable production can be performed.
　That is, in the hot stamp molded body according to the present embodiment,
(I) a plating step of immersing the steel material in a plating bath to obtain a plated steel material having a plating layer, and
(II) hot stamping the plated steel material after the plating step. It is equipped with a hot stamping step and
(III) a chemical conversion treatment step for performing a chemical conversion treatment on the plated steel material after hot stamping . Cool to room temperature so that the cooling rate is 10 ° C./sec or more, the average cooling rate of 450 to 350 ° C. is 7 ° C./sec or less, and the average cooling rate of 350 to 150 ° C. is 4 ° C./sec or less. It can be obtained by a manufacturing method.

[0038]

[Immersion in plating bath] In the
　plating process, a steel material such as a steel plate to be a raw plate is immersed in a plating bath to form a plating layer on the surface.
　Regarding the conditions for immersion in the plating bath, for example, the surface of the original plating plate is heat-reduced at 600 to 940 ° C, air-cooled with N2 gas , the temperature of the steel material reaches the bath temperature + 20 ° C, and then 500 to 750. Immerse in a plating bath at a bath temperature of ° C. for about 0.2 to 6 seconds.
　If the immersion time is less than 0.2 seconds, the plating layer may not be sufficiently formed. On the other hand, if the immersion time exceeds 6 seconds, the plating layer and the steel material are excessively alloyed, and a large amount of Fe is contained in the plating layer. When excess Fe is contained in the plating layer, it becomes difficult to suppress the evaporation of Zn and Mg during the heating of the hot stamp. Therefore, when the immersion time is more than 6 seconds, the chemical conversion treatment film having a predetermined composition cannot be obtained by the subsequent chemical conversion treatment step, and the coating film adhesion of the hot stamp molded product is lowered.
　The plating bath may be set to contain Zn, Al, Mg and other elements according to the composition of the target plating layer 3. The composition of the plating bath contains, for example, Al: 30.00 to 75.00%, Mg: 4.00 to 17.00%, Si: 0.20 to 2.00%, and is used in the plating layer as needed. It contains arbitrary elements to be contained, and the balance is Zn and impurities.
[0039]
[Cooling]
Average cooling rate from bath temperature to 450 ° C: 10 ° C / sec or more
　In the method for manufacturing a hot stamped compact according to the present embodiment, the average temperature range up to 450 ° C after the plated steel material is pulled up from the plating bath. Cool so that the cooling rate is 10 ° C./sec or higher. By setting the average cooling rate in this temperature range to 10 ° C./sec or more, it is possible to suppress the formation of Al oxide on the surface of the plated steel material.
[0040]
Average cooling rate of 450 to 350 ° C.: 7 ° C./sec or less Following
　the above cooling, cooling is performed so that the average cooling rate in the temperature range of 450 ° C. to 350 ° C. is 7 ° C./sec or less.
　By controlling the solidification structure by lowering the cooling rate in this temperature range, oxides of Mg and Ca having a low Al content (for example, 10% or less) are formed on the surface in the subsequent hot stamping step. Will be done. As a result, when the chemical conversion treatment is performed, a chemical conversion treatment film containing Mg and Ca can be obtained with less scale.
　Further, in the case of a zinc-based plating layer, there is a concern that Zn (zinc) evaporates due to hot stamping, but in the solidified structure controlled as described above, although the detailed mechanism is not clear, an element having a high vapor pressure. Al, Zn, Ca and / or Si-containing intermetallic compounds having the effect of suppressing the evaporation of Zn and Mg are preferentially generated in the vicinity of the surface of the plating layer, whereby the heating of the hot stamp is continued. Evaporation of Zn and Mg at that time can be suppressed.
[0041]
Average cooling rate of 350 to 150 ° C.: 4 ° C./sec or less Following
　the above cooling, when the average cooling rate of 350 ° C. to 150 ° C. is set to 4 ° C./sec or less, the solid solution of Al and Zn contained in the solidified structure is formed. Separation into the Al phase and the Zn phase lowers the melting point of the plating layer, and the intermetallic compound containing Al, Zn, Ca and / or Si moves to the surface of the plating layer in a molten state during hot stamp heating. It will be easier to do. As a result, it becomes possible to suppress the evaporation of Zn and Mg more efficiently, and it becomes possible to form a chemical conversion treatment film containing Mg and Ca.
　However, even if the average cooling rate of 350 ° C. to 150 ° C. is 4 ° C./sec or less, if the cooling rate in a part of the temperature range is high, a preferable metal structure cannot be obtained. Therefore, the average cooling rate of 350 ° C. to 150 ° C. is 4 ° C./sec or less, the average cooling rate of 350 ° C. to 250 ° C. is 4 ° C./sec or less, and the average cooling rate of 250 to 150 ° C. is 4 ° C./sec. It is preferably less than a second.
[0042]

　Hot stamping is performed on the plated steel material (a steel material having a base material and a plating layer formed on the surface thereof) after the plating process.
　The conditions for hot stamping are not limited, but for example, a method of heating a plated steel sheet to 750 to 1200 ° C., holding it for 0 to 8 minutes, and then sandwiching the plated steel sheet with a flat plate mold at a temperature of about room temperature to quench it can be mentioned. Be done.
[0043]

　A chemical conversion treatment is performed on the molded product after hot stamping. The chemical conversion treatment is not limited, and a known zinc phosphate treatment may be used.
[0044]
　According to the above-mentioned manufacturing method, the hot stamp molded product according to the present embodiment can be obtained.
Example
[0045]
　Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.
[0046]
　Tables 1 to 3 show examples disclosed in the present invention. Various Zn-Al-Mg-based plating baths were built and subjected to hot stamp heating. A steel plate having a thickness of 1.6 mm (including C: 0.2% and Mn: 1.3%) was used as the plating original plate. After cutting the original plate to 100 mm × 200 mm, plating was performed with a batch-type hot-dip plating test device manufactured in-house. The plate temperature was measured using a thermocouple spot-welded to the center of the original plating plate. Before immersion in the plating bath, the surface of the plating original plate is heat-reduced at 800 ° C. in an N 2-5% H 2 gas atmosphere in a furnace with an oxygen concentration of 20 ppm or less, and air-cooled with N 2 gas to
　raise the immersion plate temperature to +20. After reaching ℃, it was immersed in a plating bath having a bath temperature shown in Table 2 for about 3 seconds. After soaking in the plating bath, it was pulled up at a pulling speed of 20 to 200 mm / sec. 　At the time of pulling up, the amount of plating adhered was controlled by N 2 wiping gas as shown in Table 2. After pulling up the steel sheet from the plating bath, it was cooled from the plating bath temperature to room temperature under the conditions shown in Table 2. 　The produced plated steel sheet was subjected to hot stamp heating and die quenching. As for the heating conditions, the plated steel sheet is inserted into a heating furnace at 900 ° C, and after the temperature of the plated steel sheet reaches the temperature inside the furnace of -10 ° C, it is retained for 0 to 8 minutes, and then the flat plate mold is at a temperature of about room temperature. A molded product was produced by sandwiching a plated steel sheet with a steel sheet and quenching it. 　As a result of investigation by the above-mentioned method, the chemical composition of the plating layer after hot stamping was as shown in Table 1.

　No. No. 31 was hot stamped on a commercially available alloyed hot-dip galvanized steel sheet.
[0047]
　After that, a sample of 50 x 100 mm (x plate thickness) was taken from the steel material after hot stamping, and this sample was subjected to zinc phosphate treatment (SD5350 system: standard manufactured by Nippon Paint Industrial Coding Co., Ltd.) for chemical conversion. A treated film was formed.
[0048]
[table 1]

[0049]
[Correction under Rule 91 19.10.2021]　
[Table 2]

[0050]
In order to investigate the chemical conversion treatment film, the prepared sample was dissolved with 20% chromic acid, the solution in which the chemical conversion treatment film was dissolved was subjected to ICP analysis, and the average composition of the chemical conversion treatment film was measured. In addition, the amount of adhesion per side was measured from the weight change before and after dissolution.
　Moreover, the ratio (area%) of the scale of the chemical conversion treatment film was measured by observing the surface of the plated steel sheet on which the chemical conversion treatment film was formed by SEM. At that time, in the SEM observation field of view, the area ratio of the region where the steel plate was exposed was defined as the ratio of the scale. When the ratio of the scale was 10 area% or less, it was judged that the scale was suppressed.
　The sample after the chemical conversion treatment was cut into 25 mm (C direction) × 15 mm (L direction) to obtain an SEM image of the sample surface. Based on this SEM image, the shape of zinc phosphate crystals was observed. As a result, in the example of the invention, it was confirmed that the zinc phosphate crystal was scaly with a major axis of 10 μm or less and a minor axis of 5 μm or less.
[0051]

　As described above, the coating film adhesion of the hot stamped product is such that the sample 50 × 100 mm is treated with zinc phosphate (SD5350 system: Nippon Paint Industrial Coding Co., Ltd. standard). After that, electrodeposition coating (PN110 Power Nix Gray-: Nippon Paint Industrial Coding Co., Ltd. standard) was performed so that the coating film thickness was 20 μm, and baking was performed at a baking temperature of 150 ° C. for 20 minutes. After that, the coated galvanized steel sheet with cross-cut scratches (40 x √2 mm, 2 pieces) reaching the base iron was immersed in 5% NaCl salt water at 55 ° C. for 1000 hours, and then the electrodeposition coating film was peeled off by tape peeling. It was evaluated from the area ratio of the part where the peeling occurred and the red rust occurrence situation.
　"AA" when the peeling area is 5% or less, "A" when the peeling area is more than 5% to 10%, and "B" when the peeling area is more than 10% or red rust has occurred. did.
[0052]
　The results are shown in Table 3.
[0053]
[Table 3]

[0054]
　No. which is an example of the present invention. In 3, 5 to 10, 17 to 20, 23 to 26, 28, and 29, a plated steel sheet is prepared under appropriate manufacturing conditions and hot stamped so that a chemical conversion coating containing Mg and Ca is formed on the plated layer. Was formed in. As a result, it had excellent coating film adhesion.
　FIG. 2 shows No. 1 in Tables 1 to 3. 10 SEM images (BSE images). Zinc phosphate crystals were formed on the surface of the sample, and no skeleton without zinc phosphate crystals was observed. As a result of ICP analysis, zinc phosphate crystals contained 33.5% of Mg and 2.6% of Ca.
　On the other hand, in the comparative example in which the chemical composition of the plating layer was outside the scope of the present invention or the production method was not preferable, the composition of the chemical conversion coating film and / or the area ratio of the scale was large, and the adhesion to the coating film was low. For example, No. In No. 12, as shown in FIG. 3, the zinc phosphate film 13 did not contain Ca and Mg, and a large amount of scale 12 was also observed.
　In addition, No. 1 which was hot stamped on a commercially available alloyed hot-dip galvanized steel sheet. Even at 28, the coating film adhesion was inferior.
Code description
[0055]
　　1 Hot stamp molded body
　　2 Base material
　　3 Plating layer
　　4 Chemical conversion coating
　　11 Zinc phosphate crystals containing Mg and Ca
　　12 Scale
　　13 Zinc phosphate crystals not containing Mg and Ca
The scope of the claims
[Claim 1]
　It comprises a base material made of steel,
　a plating layer formed on the surface of the base material,
　and a chemical conversion treatment film formed on the surface of the plating layer,
and the chemical composition of the plating layer is 　Al
　in mass%.
: 20.00 to 45.00%,
　Fe: 10.00 to 45.00%,
　Mg: 4.50 to 15.00%,
　Si: 0.10 to 3.00%,
　Ca: 0.05 to 3 .00%,
　Sb: 0 to 0.50%,
　Pb: 0 to 0.50%,
　Cu: 0 to 1.00%,
　Sn: 0 to 1.00%,
　Ti: 0 to 1.00%,
　Sr : 0 to 0.50%,
　Cr: 0 to 1.00%,
　Ni: 0 to 1.00%,
　Mn: 0 to 1.00%, and 　the
balance is Zn and impurities.
However, it is composed of zinc phosphate crystals containing Mg: 5.0 to 50.0% and Ca: 0.5 to 5.0% in mass%, and the
　amount of one-sided adhesion of the chemical conversion coating film is 0.1. ~ 10.0 g / m 2 ,
A hot stamp molded body characterized by that.
[Claim 2]
　The chemical composition of the plating layer is characterized by containing one or two types of
　Al: 25.00 to 35.00% and
　Mg: 6.00 to 10.00% in mass%. The hot stamp molded body according to claim 1.

[Claim 3]
The hot stamp molded product according to claim 1 or 2, wherein 　the one-sided adhesion amount of the chemical conversion-treated film is 1.5 to 8.0 g / m 2 .