Method for producing high-strength steel plate having superior deep drawing characteristics

A technology of high-strength steel plate and manufacturing method, applied in manufacturing tools, chemical instruments and methods, coatings, etc., can solve problems such as uncontrollable increase of r value

Inactive Publication Date: 2014-04-23
JFE STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The purpose of bending is to introduce dislocations into the steel plate and promote the precipitation of carbides. For this technology, it is impossible to control the texture of the parent phase ferrite to increase the r value

Method used

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  • Method for producing high-strength steel plate having superior deep drawing characteristics

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Embodiment

[0105] Next, examples of the present invention will be described.

[0106]Molten steel having the composition shown in Table 1 was melted in a converter, and slabs were produced by continuous casting. These billets were heated to 1250° C. and rough rolled to form thin slabs, followed by finish rolling under the conditions shown in Table 2, and then coiled to obtain hot-rolled sheets. After pickling this hot-rolled sheet, cold rolling was performed at a rolling ratio of 65% to form a cold-rolled sheet with a sheet thickness of 1.2 mm. On the continuous annealing line, the cold-rolled sheet was annealed at the annealing temperature shown in Table 2, and strain was applied under the conditions in Table 2 at this time. The amount of strain applied to the steel sheet is adjusted by adjusting the tensile stress generated by the tension applied to the steel sheet or the bending stress generated by rolling up to the roll. Regarding the tensile stress, the actual tension is measured ...

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Abstract

Provided is a high-strength steel sheet having excellent deep drawability with a tensile strength of 390 to 700 MPa and an r-value of 1.1 or more in the orientation in which the r-value is lowest. A steel slab formed of a composition containing, by mass, 0.0005% to 0.040% of C, 1.5% or less of Si, 0.5% to 3.0% of Mn, 0.005% to 0.1% of P, 0.01% or less of S, 0.005% to 0.5% of Al, 0.005% or less of N, and one or more of 0.5% or less of Nb, 0.5% or less of Ti, and 0.5% or less of V is subjected to finish rolling by hot rolling at a finish rolling delivery temperature of 800°C or higher, coiling at 550°C to 720°C, and cooling to form a hot-rolled steel sheet. The hot-rolled steel sheet is pickled and cold-rolled to a rolling reduction of 50% to 85% to form a cold-rolled steel sheet. The cold-rolled steel sheet is annealed at an annealing temperature of 760°C to 950°C. In this step, a strain of 0.1% to 2.0% is applied in the temperature range of 700°C to the annealing temperature.

Description

[0001] Technical area [0002] The present invention relates to a method for producing a high-strength steel sheet having a tensile strength of 390 MPa to 700 MPa and excellent deep drawability, which is useful for applications such as steel sheets for automobiles. Background technique [0003] In recent years, from the viewpoint of protecting the global environment, in order to limit CO 2 emissions, requiring improvements in the fuel efficiency of automobiles. Furthermore, in order to ensure the safety of passengers during a collision, it is also required to improve the safety centering on the collision characteristics of the automobile body. Therefore, the weight reduction of the vehicle body for the purpose of improving the fuel efficiency of the vehicle and the strengthening of the vehicle body for the purpose of improving the crash performance of the vehicle are being actively promoted. [0004] In order to satisfy both weight reduction and reinforcement of automobile b...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D9/48C22C38/14C22C38/38
CPCC21D8/0236C22C38/14C23C2/00C22C38/02C21D8/0273C23C2/02C21D9/48C22C38/12C22C38/04C21D2211/005C22C38/44C22C38/26C22C38/06C21D8/0226B32B15/013C22C38/28C22C38/001C22C38/24C22C38/38C23C2/024C23C2/0224C21D8/02
Inventor 奥田金晴田中靖
Owner JFE STEEL CORP
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