| 摘要 |
PURPOSE:To obtain an impeller for a refrigerator having high strength and superior toughness at low temp. by subjecting a steel contg. specified percentages of C, Si, Mn, Ni and Mo to normalizing, hardening and tempering under specified conditions. CONSTITUTION:A steel consisting of, by weight, 0.27-0.32% C, 0.15-0.35% Si, 0.5-0.7% Mn, 3.3-3.8% Ni, 0.4-0.5% Mo and the balance Fe with accompanying impurities is normalized by heating to 860-930 deg.C and air cooling. The steel is hardened by heating to 860-890 deg.C and oil quenching, and it is tempered by heating to 550-570 deg.C and air cooling. An impeller for a refrigerator having high performance and safety can be manufactured.
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