CN-117222774-B - Steel sheet for hot stamping and hot stamping member

Abstract

A steel sheet for hot stamping, comprising a surface-treated coating layer having a portion having a surface emissivity of 60% or more at a wavelength of 8.0 [ mu ] m at 25 ℃, and a portion not having the surface-treated coating layer, wherein the surface-treated coating layer contains carbon black and 1 or more oxides selected from the group consisting of Zr oxide, zn oxide and Ti oxide, and wherein the carbon black and the oxides are dispersed throughout the surface-treated coating layer, and wherein the surface-treated coating layer has a silica content of 0 to 0.3g/m 2 , and wherein the carbon black and the oxides are adhered in amounts of X CB (g/m 2 )、X Oxide (g/m 2 ) to satisfy the following formula. 118.9≤ 24280/{ 6700/(100+76X CB )+18000/(130+65×X Oxide ) }.

Inventors

• Miki tsuki
• Kaminishi Kenta
• FUJITA SOSHI
• Futa masahiro

Assignees

• 日本制铁株式会社

Dates

Publication Date

20260512

Application Date

20210408

Claims (10)

1. 1. A steel sheet for hot stamping, which comprises, on at least one surface side of a single steel sheet, a portion having a surface-treated coating, the portion having a emissivity of 60% or more at a wavelength of 8.0 [ mu ] m at 25 ℃, and a portion not having the surface-treated coating, The surface-treated coating film contains carbon black and 1 or more oxides selected from the group consisting of Zr oxide, zn oxide and Ti oxide, and the carbon black and the oxides are dispersed throughout the surface-treated coating film, The content of the silicon dioxide of the surface treatment coating film is 0-0.3 g/m 2 , When the amounts of carbon black and the oxide to be adhered are X CB （g/m 2 ）、X Oxide （g/m 2 ), the following formula (1) is satisfied, 118.9.Ltoreq. 24280/{ 6700/(100+76X CB ）+18000/（130+65×X Oxide ) }≤332.0 of the formula (1).
2. 2. The steel sheet for hot stamping according to claim 1, wherein the surface-treated coating film contains 5.0 to 40.0% by volume of the carbon black and 1.0 to 30.0% by volume of the oxide.
3. 3. The steel sheet for hot stamping according to claim 1 or 2, wherein a ratio X Oxide /X CB of the carbon black adhering amount X CB （g/m 2 ) to the oxide adhering amount X Oxide （g/m 2 ) is 0.20 to 200.00.
4. 4. The steel sheet for hot stamping according to any one of claims 1 to 3, wherein an adhesion amount X CB of the carbon black is 0.030g/m 2 or more and an adhesion amount X Oxide of the oxide is 0.030g/m 2 or more.
5. 5. The steel sheet for hot stamping according to any one of claims 1 to 4, wherein the surface-treated coating has a emissivity of 60% or more at a wavelength of 8.0 μm at 700 ℃.
6. 6. The steel sheet for hot stamping according to any one of claims 1 to 5, wherein a metal plating layer is provided between the base material of the steel sheet and the surface-treated coating film on one or both surfaces of the steel sheet for hot stamping.
7. 7. The steel sheet for hot stamping according to any one of claims 1 to 6, wherein the oxide has an adhesion amount X Oxide of 0.300g/m 2 or less.
8. 8. A hot stamping member comprising a part having a surface treatment coating film on the surface of a steel sheet, and a part having no surface treatment coating film, wherein the hot stamping member comprises parts having different strengths and provided by one steel sheet, The surface treatment coating film contains 1 or more oxides selected from the group consisting of Zr oxide, zn oxide and Ti oxide, and the oxide has an adhesion amount X Oxide of 0.030g/m 2 or more, The content of the silicon dioxide of the surface treatment coating film is 0-0.3 g/m 2 .
9. 9. The hot stamping member according to claim 8, wherein when vickers hardness specified in JIS Z2244 (2009) is measured, there are a portion showing a maximum hardness HVmax and a portion showing a minimum hardness HVmin, and a difference Δvv between the maximum hardness HVmax and the minimum hardness HVmin is 150 or more.
10. 10. The hot stamped member according to claim 9, wherein both the location exhibiting the greatest hardness HVmax and the location exhibiting the least hardness HVmin are present within an area composed of a common raw material.

Description

Steel sheet for hot stamping and hot stamping member Technical Field The present invention relates to a steel sheet for hot stamping and a hot stamped member. Background In recent years, in order to protect the environment and prevent global warming, there has been an increasing demand for suppressing chemical fuel consumption, which has an influence on various manufacturing industries. For example, automobiles, which are indispensable for daily life and activities as a moving mechanism, are not exceptional, and improvement in fuel efficiency and the like by weight reduction of a vehicle body and the like are demanded. However, in automobiles, simply reducing the weight of the vehicle body may cause a decrease in safety, and thus is not allowed in terms of product quality. Therefore, in the case of reducing the weight of the vehicle body, it is necessary to ensure proper safety. The structure of an automobile is often made of iron, particularly steel sheet, and it is important to reduce the weight of the steel sheet for weight reduction of the automobile body. In addition, such a requirement for a steel sheet is also present in various industries, as well as in the automobile industry. In order to meet such a demand, it is considered to reduce the thickness of the steel sheet if only the weight of the steel sheet is reduced. However, thinning the plate thickness of the steel plate causes a decrease in the strength of the structure. Accordingly, in recent years, research and development have been conducted on steel sheets capable of maintaining or improving the mechanical strength of a structure made of steel sheets by improving the mechanical strength of the steel sheets even when the steel sheets are thinner than those used before. In general, a material having high mechanical strength tends to have a reduced shape retention in a molding process such as bending. Therefore, in the case of processing into a complicated shape, the processing itself becomes difficult. One of the methods for solving the problem of formability is a so-called "hot stamping method (also called hot stamping method, high temperature stamping method, press quenching method)". In this hot stamping method, a material to be formed is heated to a high temperature to transform the material into a structure called austenite (austenitization), a steel sheet softened by heating is stamped and formed, and after forming, the steel sheet is cooled. According to this hot stamping method, since the material is temporarily heated to a high temperature to soften it, the material can be easily stamped. Further, the mechanical strength of the material can be improved by the quenching effect by cooling after molding. Therefore, by the hot stamping method, a molded article having good shape retention and high mechanical strength can be obtained. On the other hand, depending on the components, it is sometimes required to have both a portion having high strength and a portion having low strength. This is because, on the one hand, high strength is required for protecting the person and, on the other hand, lower strength is required for absorbing energy at the time of collision in a portion other than the person to be protected. From the above point of view, for example, patent document 1 below describes a member obtained by joining at least 2 Zn-based plated steel sheets having different steel components. Patent document 2 below describes a technique of separately producing a cooled structure by setting a difference in average cooling rate and cooling stop temperature according to a difference in position of a steel sheet. In addition, patent document 3 below describes a technique of controlling the temperature of a die to temper a local portion after martensitic transformation, thereby improving ductility. Prior art literature Patent literature Patent document 1 International publication No. 2016/139953 Patent document 2 Japanese patent application laid-open No. 2014-161854 Patent document 3 Japanese patent laid-open publication 2016-41440 Disclosure of Invention Problems to be solved by the invention However, in order to manufacture the member described in patent document 1, it is necessary to manufacture steel sheets having different strengths, and therefore, a joining step is required in addition to increasing the load on manufacture, which is not economical. In addition, if the method described in patent document 2 is used, 2 kinds of cooling molds are required, which is economically disadvantageous or it is difficult to ensure manufacturing robustness, which is not preferable. In addition, even when the technique described in patent document 3 is used, it is not preferable because it is difficult to secure manufacturing robustness as in patent document 2. As can be seen from this, a technique capable of performing hot stamping while suppressing an increase in cost and ensuring product robustness has been demanded. The present invention has been made