| 摘要 |
PROBLEM TO BE SOLVED: To provide prehardened, high toughness steel for plastic molding metallic mold which has excellent machinability, further has excellent rusting resistance and mirror finishing properties, and has sufficient strength and high toughness as a metallic mold product. SOLUTION: The steel has a composition comprising, by mass,≤0.15% C, 0.2 to 1.0% Si, 0.5 to 2.0% Mn, 2.0 to 5.0% Cr, 0.5 to 2.0% Cu, 2.5 to 4.5% Ni, 0.8 to 2.0% Mo and 0.5 to 1.5% Al, and the balance Fe with inevitable impurities. Then, an intermetallic compound NiAl,ε-Cu and an embrittlement phase are precipitated into a matrix mainly made up of martensite or bainite, and refining is performed to obtain a hardness of 35 to 50 HRC. The steel can comprise, by mass, 0.05 to 0.15% S and≤0.3% V as well. COPYRIGHT: (C)2004,JPO
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