| 摘要 |
PROBLEM TO BE SOLVED: To improve the stress corrosion cracking resistance of a material by executing forging at specified temp. and draft as treatment before heat treatment for a heat resistant alloy having a specified compsn. SOLUTION: A hot rolling stock of a heat resistant alloy having a compsn. contg., by weight, 35 to 39% Ni, 16 to 20% Cr, 18 to 22% Co, 2.5 to 3.5% Mo and 2.5 to 3% Ti, and the balance Fe is forged at less than the crystallization temp. of <=900 deg.C and at 10 to 30% draft and is thereafter subjected to ordinary treatment. Preferably, the forging temp. is regulated to the one from 816±8 deg.C, i.e., the stabilizing temp. at the time of the heat treating to 900 deg.C, and the draft is regulated to 20 to 30%. In this way, new crystal grains free from the presence of continuous carbides are formed at the time of the heat treatment (solution treatment) to prevent its stress corrosion cracking-resistance. Furthermore, the heat treatment after the forging is composed of ordinary heat treatment, i.e., of solution treatment of water cooling at 1024±13 deg.C for 0.5 to 1 hr, stabilizing treatment of furnace cooling at 816±8 deg.C for 15 to 25 hr and precipitating treatment of air cooling at 732±8 deg.C for 15 to 25 hr.
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