Title:
METHOD FOR PRODUCING HIGH STRENGTH BOLT EXCELLENT IN DELAYED FRACTURE RESISTANCE AND RELAXATION RESISTANT CHARACTERISTIC
Document Type and Number:
Japanese Patent JP3940270
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To provide a useful method for producing a high strength bolt excellent in both of a delayed fracture resistance and a relaxation resistant characteristic, although this bolt has such high strength level as ≥1,200 N/mm2 tensile strength.
SOLUTION: A steel material for bolt contains 0.50-1.0% C, ≤0.5% Si, 0.2-1% Mn and restrains P and S to ≤0.03%, respectively, and after applying a deep drawing work to the steel material having <20% area ratio of the total of pro-eutectoid ferrite, pro-eutectoid cementite, bainite and martensite and the balance pearlite structure, a bluing treatment is applied in the temperature range of 100-400°C to the one formed as the bolt-shape by cold-heading so as to have ≥1,200 N/mm2 tensile strength, and also, excellent delayed fracture resistance and relaxation resistant characteristic.
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Inventors:
Seiichi Koike
Takashima Mitsuo
Katsuhiro Tsukiyama
Yuichi Namimura
Nobuhiko Ibaraki
Takashima Mitsuo
Katsuhiro Tsukiyama
Yuichi Namimura
Nobuhiko Ibaraki
Application Number:
JP2001083281A
Publication Date:
July 04, 2007
Filing Date:
March 22, 2001
Export Citation:
Assignee:
Honda motor industry stock company
Saga Iron Works Co., Ltd.
KABUSHIKI KAISHA KOBE SEIKO SHO
Saga Iron Works Co., Ltd.
KABUSHIKI KAISHA KOBE SEIKO SHO
International Classes:
C21D9/00; F16B31/02; C21D1/26; C21D8/06; C22C38/00; C22C38/04; C22C38/06; C22C38/30; F16B35/00; (IPC1-7): C21D9/00; C21D1/26; F16B31/02; F16B35/00; //C21D8/06; C22C38/00; C22C38/04; C22C38/30
Domestic Patent References:
| JP11315347A | ||||
| JP8003640A |
Attorney, Agent or Firm:
Kyuichi Ueki
Etsushi Kotani
Etsushi Kotani