| abstract |
One type of stainless steel with two phases includes, in mass%, less than 0.03% of carbon, 0.01 to 2% of Si, 0.1 to 2% of Mn, less than 0.05% of P, less than 0.001% of S, 0.003 to 0.05% of Al, 4 to 12% of Ni, 18 to 32% of Cr, 0.2 to 5% of Mo, 0.05 to 0.4% of nitrogen, less than 0.01% of Oxygen, 0.0005 to 0.005% of Ca, 0.0001 to 0.005% of Mg, 0 to 2% of Cu, 0 to 0.01% of B, 0 to 4% of tungsten, and the balance of Fe and impurities; which is characterized in that, in the impurities, the total amount of Ca and Mg is 20 to 40 mass%, and the number of oxides contained in the impurities with a long diameter larger than 7 μm is less than 10 per cross-sectional area of 1 mm<SP>2</SP> measured in a direction perpendicular to the processing direction. Furthermore, the sulfur content is more than 15 mass%, and the number of oxides contained in the impurities with a long diameter larger than 1 μm is less than 10 per cross-sectional area of 0.1 mm<SP>2</SP> measured in a direction perpendicular to the processing direction. In particular, preferably, the content of Cu, B and tungsten separately is, in mass%, 0.2 to 2%, 0.001 to 0.01%, and 0.1 to 4%. |