发明授权
- 专利标题: High strength steel sheet and method for manufacturing the same
- 专利标题(中): 高强度钢板及其制造方法
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申请号: US09827597申请日: 2001-04-05
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公开(公告)号: US06663725B2公开(公告)日: 2003-12-16
- 发明人: Tadashi Inoue , Hiroyasu Kikuchi , Sadanori Imada , Takayuki Odake
- 申请人: Tadashi Inoue , Hiroyasu Kikuchi , Sadanori Imada , Takayuki Odake
- 优先权: JP11-261418 19990916; JP2000-075482 20000317; JP2000-191410 20000626; JP2000-216316 20000717; JP2000-259595 20000829
- 主分类号: C22C3840
- IPC分类号: C22C3840
摘要:
The present invention relates to a high strength steel sheet consisting essentially of 0.04 to 0.1% C, 0.5% or less Si, 0.5 to 2% Mn, 0.05% or less P, 0.005% or less 0, 0.005% or less S, by weight, having 10 &mgr;m or less of average ferritic grain size, and 20 mm/mm2 or less of generation frequency A, which generation frequency A is defined as the total length of a banded secondary phase structure observed per 1 mm2 of steel sheet cross section along the rolling direction thereof. The steel sheet is manufactured by, for example, a method comprising the steps of: hot-rolling a continuously cast slab having the composition described above at temperatures of Ar3 transformation point or above directly or after reheating thereof; and cooling the hot-rolled steel sheet within 2 seconds down to the temperatures of from 600 to 750° C. at cooling speeds of from 100 to 2,000° C./sec, followed by coiling the cooled steel sheet at temperatures of from 450 to 650° C. The present invention provides a high strength steel sheet having strengths of 340 MPa or more and having excellent stretch flanging performance, ductility, and shock resistance, providing a sufficient coil shape with good surface properties, even when hot dip zinc-coating is applied.
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