| 摘要 |
PROBLEM TO BE SOLVED: To provide high strength dual phase stainless steel having a dual phase structure of ferrite and martensite, having hardness of >=400 Hv, small in the variation of hardness and having an excellent shape flattening degree. SOLUTION: This steel has a composition containing 0.10 to 0.20% C, <=2.0% Si, <=2.0% Mn, <=0.040% P, <=0.010 S, 0.50 to 4.0% Ni, 10.0 to 20.0% Cr, <=0.10% N and 0 to 0.015% B, if required, further containing one or more kinds selected from <=2.0% Cu, <=2.0% Mo, <=0.50% Ti, <=0.50% Nb, <=0.2% Al, <=0.2% rare earth metals, <=0.2% Y, <=0.1% Ca and <=0.10% Mg, in which the valueγcmax defined by the following formula lies in the range of 60 to 95, and the balance substantially Fe:γcmax=(420C+470N+23Ni+7Mn+18Cu)-(11.5Cr+11.5Si+13.5Mo+49Ti+53Nb+52Al)+1 68.
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