发明授权
- 专利标题: High-strength steel pipe excellent in low temperature toughness and toughness at weld heat-affected zone
- 专利标题(中): 焊接热影响区的低温韧性和韧性优良的高强度钢管
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申请号: US10444743申请日: 2003-05-23
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公开(公告)号: US07601231B2公开(公告)日: 2009-10-13
- 发明人: Takuya Hara , Hitoshi Asahi
- 申请人: Takuya Hara , Hitoshi Asahi
- 申请人地址: JP Tokyo
- 专利权人: Nippon Steel Corporation
- 当前专利权人: Nippon Steel Corporation
- 当前专利权人地址: JP Tokyo
- 代理机构: Baker Botts LLP
- 优先权: JP2002-152379 20020527; JP2002-377829 20021226
- 主分类号: C22C38/04
- IPC分类号: C22C38/04 ; C22C38/14 ; C22C38/12
摘要:
A high-strength steel pipe excellent in weldability on site and a method for producing the steel pipe by improving the reliability of the low temperature toughness of a steel are provided. For example, the steel pipe includes elements to enhance hardenability for furthering high-strengthening and also improving toughness at a weld heat affected zone subjected to double or more layer welding. In the method, the steel is made to consist of a structure composed of bainite and/or martensite by containing prescribed amounts of C, Si, Mn, P, S, Ni, Mo, Nb, Ti, Al and N, and, as occasion demands, one or more of B, V, Cu, Cr, Ca, REM, and Mg, and regulating C, Si, Mn, Cr, Ni, Cu, V and Mo. Such elements enhancing hardenability, by a specific relational expression. The diameter of prior austenite grains may be regulated in a prescribed range. The method may include heating a casting to a temperature not lower than the Ac3 point, hot rolling such casting, and thereafter cooling the resulting hot-rolled steel plate at a prescribed cooling rate.