| 摘要 |
PURPOSE: To produce a martensitic stainless steel excellent in hot workability, sulfide stress cracking resistance, and toughness. CONSTITUTION: A steel, which has a composition consisting of, by weight, 0.1-0.3% C, 0.01-1.0% Si, 0.1-1.0% Mn, <=0.02% P, <=0.01% S, 11-14% Cr, <0.05% Ni, 0.015-0.1% N, and the balance Fe with impurities or further containing 0.001-0.3% each of one or more kinds among Ca, Mg, and REM, and satisfyingγval.=13C+11.5N-Cr>=-10.86, is used. This steel is hot-worked, cooled down to room temp., heated to 880-1050 deg.C, cooled down to a cooling stoppage temp. of 600-350 deg.C at a rate of >=2 deg.C/sec, air-cooled to room temp., and tempered at a temp. not higher than Ac1 . By this method, the steel, superior to the conventional steel in toughness and sulfide stress cracking resistance in a state of the chemical composition of the conventional steel such as AISI420, can be obtained.
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