Steel sheet

一种钢板、化学组成的技术,应用在高强度钢板领域,能够解决兼顾强度成型性的提高困难、无法得到充分的特性、成型性扩孔性困难等问题,达到优异外观、优异强度及成型性、抑制表面缺陷的效果

Active Publication Date: 2019-03-01
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, it is difficult to achieve both strength improvement and formability improvement
Technologies aiming at both strength improvement and formability improvement have been proposed, but sufficient properties cannot be obtained by these technologies
In addition, in recent years, further improvement in strength has been required, and technologies aimed at improving formability have been proposed, but it is difficult to improve formability, especially hole expandability.
On the other hand, with the improvement of the productivity of the steel plate, the excellent hole expandability under the condition of increasing the test speed in the quality investigation of the steel plate is expected, but the hole expandability when the processing speed is fast is difficult for the conventional steel plate. Sexual enhancement is difficult

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0153] Next, examples of the present invention will be described. The conditions in the examples are an example of conditions adopted for confirming the feasibility and effects of the present invention, and the present invention is not limited to the examples of conditions. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.

no. 1 Embodiment

[0155] Slabs having the chemical compositions shown in Table 1 were produced, and after heating the slabs to 1250° C. for 1 hour, multiaxial compression processing was performed under the conditions shown in Table 2. Next, the slab was reheated to 1250° C., and rough rolled to obtain a rough rolled sheet. Thereafter, the rough-rolled steel sheet was reheated at 1250° C. for 1 hour, and finish-rolled under the conditions shown in Table 2 to obtain a hot-rolled steel sheet. It should be noted that, in this experiment, in the arrangement of the experimental equipment, since the temperature of the slab had to be lowered, reheating was carried out. heating. In the finish rolling, the first rolling was performed in 4 steps, the second rolling was performed in 2 steps, and after coiling, it was kept at the coiling temperature for 1 hour. Thereafter, the hot-rolled steel sheets were pickled, and cold-rolled at the rolling reductions shown in Table 2 to obtain cold-rolled steel sheet...

no. 2 Embodiment

[0171] Slabs having the chemical compositions shown in Table 5 were produced, and after heating the slabs to 1250° C. for 1 hour, multiaxial compression processing was performed under the conditions shown in Table 6. Next, the slab was reheated to 1250° C. and rough-rolled to obtain a rough-rolled sheet. Thereafter, the rough-rolled steel sheet was reheated at 1250° C. for 1 hour, and finish-rolled under the conditions shown in Table 6 to obtain a hot-rolled steel sheet. It should be noted that, in this experiment, in the arrangement of the experimental equipment, since the temperature of the slab had to be lowered, reheating was carried out. heating. In the finish rolling, the first rolling was performed in 4 steps, the second rolling was performed in 2 steps, and after coiling, it was kept at the coiling temperature for 1 hour. Thereafter, the hot-rolled steel sheets were pickled, and cold-rolled at the rolling reductions shown in Table 6 to obtain cold-rolled steel sheets...

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Abstract

A steel sheet has a specified chemical composition and has a steel structure such that, in area ratio, 5%-80% is ferrite and 20%-95% is a hard structure made of bainite, martensite or retained austenite or a chosen combination of same, and the standard deviation for the hard structure line fraction on a line in a plane orthogonal to the thickness direction is 0.050 or less in the range of depths from the surface of 3t / 8 to t / 2 when t is the thickness of the steel sheet.

Description

technical field [0001] The present invention relates to a high-strength steel sheet suitable for mechanical structural parts such as automobile body structural parts. Background technique [0002] In order to suppress the emission of carbon dioxide gas from automobiles, weight reduction of automobile bodies using high-strength steel sheets has been progressing. In addition, in order to ensure the safety of passengers, more and more high-strength steel plates are being used in vehicle bodies. In order to further reduce the weight of the vehicle body, it is important to further improve the strength. On the other hand, depending on the parts of the vehicle body, excellent formability is required. For example, high-strength steel sheets for frame-based parts are required to have excellent elongation and hole expandability. In particular, high-strength steel sheets used as structural members of automobiles, that is, machine parts (subframes) and reinforcements (reinforcing mem...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C22C38/58C21D9/46
CPCC22C38/00C22C38/58C21D9/46C21D6/005C21D6/008C21D8/0205C21D8/0226C21D8/0236C21D8/0263C21D2211/001C21D2211/002C21D2211/008C22C38/001C22C38/002C22C38/005C22C38/02C22C38/04C22C38/06C22C38/08C22C38/12C22C38/14C22C38/16C22C38/18C21D2211/005
Inventor 薮翔平上西朗弘林宏太郎
Owner NIPPON STEEL CORP
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