| 摘要 |
PROBLEM TO BE SOLVED: To stably produce a steel thin sheet having high tensile strength and fracture elongation and furthermore excellent in corrosion resistance by specifying the componental compsn. of a quasi-stable austenitic stainless steel, the amt. of strain induced martensite and the grain size of austenite before the formation of the above phases. SOLUTION: A quasi-stable austenitic stainless steel contg., by weight, 0.01 to 0.2% C, 0.05 to 3% Si, 0.08 to 3% Mn, 6 to 7.4% Ni, 13 to 20% Cr and 0.05 to 0.5% Cu is used. This steel is produced into a steel thin sheet by the process of cold rolling before final annealing-final annealing-final cold rolling-aging treatment. Then, the cold rolling ratio in the final cold rolling is regulated to >=40%, the temp. in the final annealing is regulated to 950 to 1,000 deg.C, and the time therefor is regulated to the range of 1 to 30sec. By this method, the objective steel thin sheet composed of the steel having the above compsn. and contg. strain induced martensitic phases by >=30vol.%, and in which the grain size of austenite before the formation of the strain induced martensitic phases is regulated to <=15μcan be obtd.
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