| 摘要 |
PROBLEM TO BE SOLVED: To provide alloy steel which can maintain high hardenability, high toughness and high resistance to temper softening even in the case where cooling rate at hardening is relatively low. SOLUTION: The alloy steel has a composition which consists of, by mass, 0.40 to 0.60% C, 0.02 to 2.00% Si, 0.50 to 2.00% Mn,≤1.00% Cu, 0.01 to 2.00% Ni, 3.00 to 6.00% Cr, 0.05 to 6.00% Mo,≤10.00% W, 0.10 to 2.00% V,≤5.00% Co and the balance substantially Fe with inevitable impurities and in which, among the inevitable impurities, P, S, Al, O and N are limited to, by mass,≤0.050%,≤0.020%,≤0.050%,≤0.0100% and≤0.0200%, respectively, and, further, Weq, Mt, Mt2 and PN (represented by Weq=2Mo+W, Mt=300C+15Mn+Cu+20Ni+2Cr+Mo+0.5W+0.2V, Mt2=15Mn+Cu+20Ni and PN=Cr+3Mn+2Ni+Cu, respectively) satisfy 3.00≤Weq≤10.00, Mt≥190, Mt2≥15 and PN≤11, respectively. COPYRIGHT: (C)2008,JPO&INPIT
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