Patent ID: 7662244

Claim:
A martensitic stainless steel comprising C: 0.01-0.08%, Si: 0.05-1%, Mn: 0.05-1.5%, P: not more than 0.03%, S: not more than 0.01%, Cr: 9-15%, Ni: 0.1-0.9%, Al: not more than 0.05% and N: not more than 0.1% in mass %, the residual being Fe and impurities, wherein the thickness of the retained austenite phase in the steel is not more than 100 nm, and wherein the X-ray integral intensities 111γ and 110α satisfy the following formula (a); 0.005≦111γ/(111γ+110α)≦0.05 (a) where 111γ is the X-ray integral intensity of austenite phase (111) plane and 110α is the X-ray intensity of martensite phase (110) plane.