发明申请
- 专利标题: Low-carbon free cutting steel
- 专利标题(中): 低碳自由切割钢
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申请号: US10898963申请日: 2004-07-27
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公开(公告)号: US20050025658A1公开(公告)日: 2005-02-03
- 发明人: Naoki Matsui , Takayuki Nishi , Toru Kato , Koji Watari , Tatsuya Hasegawa
- 申请人: Naoki Matsui , Takayuki Nishi , Toru Kato , Koji Watari , Tatsuya Hasegawa
- 申请人地址: JP Osaka-shi
- 专利权人: Sumitomo Metal Industries, Ltd.
- 当前专利权人: Sumitomo Metal Industries, Ltd.
- 当前专利权人地址: JP Osaka-shi
- 优先权: JP2003-285463 20030801
- 主分类号: C22C38/00
- IPC分类号: C22C38/00 ; C22C38/04 ; C22C38/14 ; C22C38/60
摘要:
The invention provides a low-carbon free cutting steel containing no lead and is at least comparable in machinability to the conventional leaded free cutting steels and composite free cutting steels and furthermore has excellent finished surface characteristics. The steel is a low-carbon free cutting steel which comprises, on the percent by mass basis, C: 0.05 to under 0.20%, Mn: 0.4-2.0%, S: 0.21-1.0%, Ti: 0.002-0.10%, P: 0.001-0.30%, Al: not higher than 0.2%, 0: 0.001-0:03% and N: 0.0005-0.02%, with the balance being Fe and impurities, and which satisfies the relations (a) and (b) given below concerning the inclusions contained in the steel: (A+B)/C≧0.8 (a), NA≧5 (b), wherein, A: the total area occupied by substantial MnS with Ti carbide and/or Ti carbonitride included therein among the inclusions not smaller than 1 μm in circle-equivalent diameter per mm2 of a cross section parallel to the direction of rolling; B: the total area occupied by substantial MnS with neither Ti carbide nor Ti carbonitride included therein among the inclusions not smaller than 1 μm in circle-equivalent diameter per mm2 of a cross section parallel to the direction of rolling; C: the total area occupied by all the inclusions not smaller than 1 μm in circle-equivalent diameter per mm2 of a cross section parallel to the direction of rolling; NA: the number of substantial MnS inclusions with Ti carbide and/or Ti carbonitride included therein among the inclusions not smaller than 1 μm in circle-equivalent diameter per mm2 of a cross section parallel to the direction of rolling.