Title:
耐遅れ破壊特性に優れた高強度鋼材と高強度ボルト、及び、その製造方法
Document Type and Number:
Japanese Patent JP5177323
Kind Code:
B2
Abstract:
A high strength steel material which is excellent in delayed fracture resistance containing, by mass%, C: 0.10 to 0.55%, Si: 0.01 to 3%, and Mn: 0.1 to 2%, further containing one or both of V: 1.5% or less and Mo: 3.0% or less, the contents of V and Mo satisfying V+1/2Mo>0.4%, further containing one or more of Cr: 0.05 to 1.5%, Nb: 0.001 to 0.05%, Cu: 0.01 to 4%, Ni: 0.01 to 4%, and B: 0.0001 to 0.005%, and having a balance of Fe and unavoidable impurities, the structure being a mainly tempered martensite structure, the surface of the steel material being formed with (a) a nitrided layer having a thickness from the surface of the steel material of 200 µm or more and a nitrogen concentration of 12.0 mass% or less and higher than the nitrogen concentration of the steel material by 0.02 mass% or more and (b) a low carbon region having a depth from the surface of the steel material of 100 µm or more to 1000 µm or less and having a carbon concentration of 0.05 mass% or more and 0.9 time or less the carbon concentration of the steel material.
Inventors:
Daisuke Hirakami
Senda Senda
Toshizo Tarui
Senda Senda
Toshizo Tarui
Application Number:
JP2012502334A
Publication Date:
April 03, 2013
Filing Date:
March 11, 2011
Export Citation:
Assignee:
Nippon Steel & Sumitomo Metal Corporation
International Classes:
C22C38/00; C21D1/06; C21D1/76; C21D9/00; C21D9/52; C22C38/58; C23C8/26
Domestic Patent References:
| JP2009299180A | 2009-12-24 | |||
| JPH10141341A | 1998-05-26 | |||
| JPH10226817A | 1998-08-25 | |||
| JPH10251803A | 1998-09-22 | |||
| JP2009299180A | 2009-12-24 | |||
| JPH10141341A | 1998-05-26 | |||
| JPH10226817A | 1998-08-25 | |||
| JPH10251803A | 1998-09-22 |
Attorney, Agent or Firm:
Atsushi Aoki
Takashi Ishida
Tetsuji Koga
Hiroshi Kamematsu
Yuki Yamada
Nakamura Asayuki
Nagasaka Tomoyasu
Takashi Ishida
Tetsuji Koga
Hiroshi Kamematsu
Yuki Yamada
Nakamura Asayuki
Nagasaka Tomoyasu