公开(公告)号：EP1577406A1

公开(公告)日：2005-09-21

申请号：EP03808901.7

申请日：2003-10-17

申请人： National Institute for Materials Science

发明人： TORIZUKA, Shiro ,  NAGAI, Kotobu ,  KOMATSU, Takafumi ,  MIYASHITA, Naohisa ,  TAKAGI, Fumito ,  MATSUZAWA, Masaaki ,  MIYASAKA, Yoshimasa ,  HATANO, Yoshiki ,  FUJIMORI, Chiaki ,  OSAKA, Masayoshi ,  UEMATSU, Masaaki ,  HAMA, Hajime

IPC分类号： C21D9/00 ,  C21D1/06 ,  C22C38/00 ,  C22C38/58 ,  C23C8/32 ,  F16B25/00 ,  F16B33/06

CPC分类号： C22C38/06 ,  C21D9/0093 ,  C22C38/02 ,  C22C38/04 ,  C23C8/26 ,  F16B25/00 ,  F16B33/06

摘要： A screw or a tapping screw, comprising an ultra fine structure steel having ferrite grains of 3 µm or smaller in average grain size and a nitrided layer on a surface part, wherein a strength is increased, a surface hardness is increased, and the surface hardness and an inside hardness are kept in balance, whereby a novel tapping screw and novel general screws can be provided.