Title:
PRODUCTION OF ULTRAHIGH STRENGTH STEEL SHEET EXCELLENT IN HYDROGEN EMBRITTLEMENT RESISTANCE
Document Type and Number:
Japanese Patent JP3406094
Kind Code:
B2
Abstract:
PURPOSE: To produce an ultrahigh strength steel sheet excellent in hydrogen embrittlement resistance by subjecting a slab of a steel containing specific amounts of C, Si, Mn, P, S, Ca, and Fe to hot rolling under specific conditions and to cold rolling and then subjecting the resultant sheet to continuous annealing and tempering treatments under respectively specified conditions.
CONSTITUTION: A slab of a steel, having a composition consisting of, by weight, 0.08-0.3% C, <1% Si, 1.5-3% Mn, ≤0.02% P, ≤0.01% S, 0.001-0,01% Ca, and the balance essentially Fe, is used. This steel slab is hot-rolled at ≥1100°C heating temp. and ≤600°C coiling temp. After acid pickling, cold rolling is carried out. The resultant sheet is soaked at a temp. betweeen the Ac1 point and 1000°C and annealed continuously. The sheet is cooled slowly firstly and then cooled from a temp. not lower then the Ar1 point down to a temp. not higher than the Ms point at ≥70°C/sec cooling rate. Then, tempering treatment is performed at 150-400°C for 1-20min. By this method, the ultrahigh strength steel sheet, containing ≥40% martensitic structure by volume ratio and having ≥1180MPa strength, can be obtained.
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Inventors:
Satohiro Nakajima
Fukuki Tanaka
Atsushi Miyamoto
Masataka Mizuno
Fukuki Tanaka
Atsushi Miyamoto
Masataka Mizuno
Application Number:
JP27686594A
Publication Date:
May 12, 2003
Filing Date:
November 10, 1994
Export Citation:
Assignee:
KABUSHIKI KAISHA KOBE SEIKO SHO
International Classes:
C21D8/02; C21D9/46; C22C38/00; C22C38/04; C22C38/14; (IPC1-7): C21D9/46; C21D8/02; C22C38/00; C22C38/04; C22C38/14
Domestic Patent References:
| JP3277743A | ||||
| JP4268016A | ||||
| JP6299248A | ||||
| JP5328515A | ||||
| JP5644723A | ||||
| JP55134155A | ||||
| JP59104428A | ||||
| JP6338520A |
Attorney, Agent or Firm:
Itsuro Makino