公开(公告)号：EP0987341A4

公开(公告)日：2006-04-05

申请号：EP99939203

申请日：1999-03-05

申请人： JFE STEEL CORP

发明人： NAMIKAWA MISAO ,  TAKADA YOSHIKAZU ,  KASAI SHOJI ,  NINOMIYA HIRONORI ,  YAMAJI TSUNEHIRO ,  HIRATANI TATSUHIKO

IPC分类号： C21D8/12 ,  C22C38/00 ,  C22C38/02 ,  C23C10/08 ,  C23C10/46 ,  C23C10/60 ,  C23C16/24 ,  C23C16/56

CPC分类号： C23C16/56 ,  C21D8/1255 ,  C22C38/004 ,  C22C38/02 ,  C23C10/08 ,  C23C10/46 ,  C23C10/60 ,  C23C16/24

摘要： A silicon steel sheet having low iron loss of high frequency has a surface layer of the steel sheet which has Si concentration higher than Si concentration of a center portion of the steel sheet. Si concentration of sheet thickness center is 3.4 wt. % or more and Si concentration of the surface layer of the steel sheet is 5 wt. % or more. Si concentration in a surface layer portion is 5 to 8 wt. %. The production method comprises siliconizing treatment and diffusing treatment. Velocity of siliconizing and diffusing are controlled, and Si concentration distribution in the sheet thickness direction of the steel sheet is controlled.