MARTENSITIC STAINLESS STEEL MATERIAL

Claims

A martensitic stainless steel material is provided that has excellent resistance to SSC. A martensitic stainless steel material of the present disclosure has the chemical composition described in the description, and in the steel material, a Number Density ND1 of fine low-S inclusions, which are inclusions containing S and for which Fn1 defined by formula (1) is 5.0 or more and which have an equivalent circular diameter of 2.0 to 10.0 µm, is 3.0 / mm² or more; a Number Density ND2 of coarse low-S inclusions, which are inclusions containing S and for which Fn1 is 5.0 or more and which have an equivalent circular diameter of more than 10.0 µm, is 2.0 / mm² or less; and a Number Density ND3 of high-S inclusions, which are inclusions containing S and for which Fn1 is less than 5.0 and which have an equivalent circular diameter of 2.0 µm or more. It's 2,0 / mm 2 or less: Fn1 = (Mg + Al + Ca + Ti + V + Mn) / S (1) where, in formula (1), each element symbol is replaced by a mass percent content of the corresponding element in the inclusions.