| 摘要 |
PURPOSE:To enhance the toughness, ductility and strength of a largesized maraging steel product by subjecting the product to soln. heat treatment and heat treatment in austenite and martensite two-phase zone to form a very fine martensite structure. CONSTITUTION:An 18% Ni maraging steel product is soln.-heat-treated by heating to 850-950 deg.C, cooled to form a martensite structure, and heated to the temp. zone of 550-750 deg.C in which austenite and martensite two phases coexist. The product is then cooled to form an austenite and martensite two-phase structure, which is heated again to the austenite temp. zone of 750-900 deg.C and held for 0.5hr to perform secondary soln. heat treatment. By this treatment the austenite grains are made fine, and they are transformed into martensite by cooling. Thus, a very fine martensite single structure is formed, and the toughness, ductility and strength of the product are improved. |
