| 摘要 |
<P>PROBLEM TO BE SOLVED: To secure high strength and high toughness without a production method requiring rapid cooling such as liquid immersion even in a large-sized steel member. <P>SOLUTION: The steel member has a composition containing, by mass, 0.10 to 0.20% C, 0.10 to 0.50% Si, 0.40 to 1.20% Mn, 2.00 to 3.00% Ni, 0.20 to 0.70% Cr and 0.10 to 0.50% Mo, and, when desired, comprising either or both of ≤0.05% V and 20 to 150 ppm N, and the balance Fe with inevitable impurities. In the method for producing a high strength and high toughness cast steel product, the steel product is annealed at 1,000 to 1,100°C, is quenched at 850 to 950°C, is tempered at 610 to 670°C, and is, when desired, further subjected to stress relieving annealing at <610°C. Upon austenitizing treatment including the quenching, cooling is performed at a cooling rate slower than that in cooling by liquid immersion. <P>COPYRIGHT: (C)2011,JPO&INPIT |
