| 摘要 |
PROBLEM TO BE SOLVED: To provide a cast steel for heat treatment, capable of securing superior mechanical properties, particularly hardness and toughness, excellent in weldability and machinability, and having superior castability required of a casting. SOLUTION: The cast steel has a composition consisting of, by weight, 0.4-0.65% C, 0.3-1.4% Si, 0.01-0.4% S, 0.3-1.0% Mn, 5.5-9.5% Cr, Mo and W in amounts within the ranges satisfying (Mo+1/2W)=1.0 to 2.0%, 0.1-0.6% V, and the balance Fe with inevitable impurities. Further, the value Z of the eutectic value represented by equation Z=8*(C%)+0.6*(Cr%) is regulated to <=10.8, and the area ratio of M7C3 carbides at the time of solidification in the structure is regulated to <=2%.
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