| 摘要 |
PURPOSE:To stabilize and improve sulfide stress corrosion cracking resistance and hydrogen cracking resistance of the titled steel, by applying two step quenchings to the titled steel from respective specified temps., next tempering at a specified temp. CONSTITUTION:The titled steel is quenched from the temp. higher than AC3 point, then quenched again from the temp. of AC1 point - AC3 point, next tempered at 625-675 deg.C. The titled steel converted to martensite by conventional quenching treatment once in such a way is heated to [austenite + ferrite] range and quenched. Thereby, the trains are refined still more than that by one time quenching, the structure in which residual austenites capable of transforming to martensite by mechanical deformation are entered therein is realized and resistances for sulfide stress corrosion cracking and hydrogen cracking are improved.
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