Invention Grant
- Patent Title: Bainite-containing-type high-strength hot-rolled steel sheet having excellent isotropic workability and manufacturing method thereof
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Application No.: US15411372Application Date: 2017-01-20
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Publication No.: US10364478B2Publication Date: 2019-07-30
- Inventor: Tatsuo Yokoi , Hiroshi Shuto , Riki Okamoto , Nobuhiro Fujita , Kazuaki Nakano , Takeshi Yamamoto
- Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
- Applicant Address: JP Tokyo
- Assignee: NIPPON STEEL CORPORATION
- Current Assignee: NIPPON STEEL CORPORATION
- Current Assignee Address: JP Tokyo
- Agency: Birch, Stewart, Kolasch & Birch, LLP
- Priority: JP2011-079658 20110331
- Main IPC: C21D9/46
- IPC: C21D9/46 ; C21D8/02 ; C22C38/06 ; C22C38/58 ; C22C38/00 ; C22C38/02 ; C22C38/04 ; C22C38/08 ; C22C38/12 ; C22C38/14 ; C22C38/16 ; C22C38/28 ; C22C38/38 ; C22C38/18 ; C21D6/00

Abstract:
The present invention provides a bainite-containing-type high-strength hot-rolled steel sheet. The steel sheet, containing C: greater than 0.07 to 0.2%, Si: 0.001 to 2.5%, Mn: 0.01 to 4%, P: 0.15% or less, S: 0.03% or less, N: 0.01% or less, Al: 0.001 to 2% and a balance being composed of Fe and impurities, has an average value of pole densities of the {100} to {223} orientation group at a sheet thickness center portion being a range of ⅝ to ⅜ in sheet thickness from the surface of the steel sheet is 4.0 or less, and a pole density of the {332} crystal orientation is 4.8 or less, an average crystal grain diameter is 10 μm or less and vTrs is −20° C. or lower, and a microstructure is composed of 35% or less in a structural fraction of pro-eutectoid ferrite and a balance of a low-temperature transformation generating phase.
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