| 摘要 |
PROBLEM TO BE SOLVED: To provide matrix high-speed steel suitable for nitriding treatment in which, in a die used after being surface hardened by nitriding treatment, alloy components on the base-material side are optimized so that resistance to crack sensitivity and also crack growth rate can be decreased in a hardened layer (nitrided layer) as compared with the conventional one. SOLUTION: The matrix high-speed steel suitable for nitriding treatment is characterized as follows: when the steel which has a composition consisting of 0.4 to 0.7% C, 0.1 to 0.6% Mn, 3.3 to 5.0% Cr, 3.0 to 4.6% Mo, 0.01 to 0.10% Al,≤0.030% N,≤0.0030% O, Si in an amount satisfying Si/Mo=0.005 to 0.100, V in an amount satisfying V/Mo=0.05 to 1.00 and the balance Fe with inevitable impurities is hardened at≥1,080°C, tempered at≥500°C and nitrided at 400 to 600°C, base-material hardness is≥55 HRC and grain size number is≥3. COPYRIGHT: (C)2007,JPO&INPIT
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