Title:
HIGH STRENGTH STEEL FOR BOLT EXCELLENT IN COLD WORKABILITY AND DELAYED FRACTURE RESISTANCE
Document Type and Number:
Japanese Patent JP3246266
Kind Code:
B2
Abstract:
PURPOSE: To produce a high strength steel for bolts excellent in cold workability and delayed fracture resistance by specifying the compsn. of a Cr-Mo low alloy steel.
CONSTITUTION: The compsn. of a steel is constituted of the one contg., by weight, 0.15 to 0.50% C, ≤0.10% Si, 0.30 to 0.55% Mn, ≤0.010% P, ≤0.010% S, 0.30 to 1.5% Cr, 0.01 to 0.6 % Mo, 0.03 to 0.10% Ti, 0.01 to 0.05% Al, 0.002 to 0.010% N and 0.0005 to 0.003% B, in which K value prescribed by the formula I satisfies the range of 0.40 to 0.60%, and N value prescribed by the formula II satisfies the range of ≥0.10%, and the balance Fe with inevitable impurities. Preferably, 0.01 to 0.1% Nb and/or 0.01 to 0.1% Y is moreover added thereto. Furthermore, this steel is worked into a bolt, which is thereafter hardened and is tempered at ≥400° to regulate its tensile strength to 1000 to 1500N/mm2.
Inventors:
Yuichi Namimura
Takehiko Kato
Hasegawa Toyofumi
Takehiko Kato
Hasegawa Toyofumi
Application Number:
JP9869495A
Publication Date:
January 15, 2002
Filing Date:
April 24, 1995
Export Citation:
Assignee:
KABUSHIKI KAISHA KOBE SEIKO SHO
International Classes:
F16B31/00; C22C38/00; C22C38/28; C22C38/32; (IPC1-7): C22C38/00; C22C38/32
Attorney, Agent or Firm:
Kyuichi Ueki
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