| 摘要 |
PURPOSE:To provide a titled stainless steel having a decreased density in pitting by incorporating a small amt. of S and Cu in a martensitic stainless steel contg. Cr and Ni and regulating respectively the average long diameter of sulfide inclusions in the optional section, the average distance in parallel with the forging surface between the inclusions, etc. CONSTITUTION:A martensitic stainless steel for a high temp. water pump is formed by incorporating 0.003-0.015% S and 0.10-0.4% Cu into a martensitic stainless steel contg. 11.5-13.5% Cr and 0.01-4.5% Ni and providing the following conditions thereto: The average long diameter of the sulfide inclusions in the optional section is regulated to <=5mum, the average distance in parallel with the forging surface between the sulfide inclusions to >=100mum and further the final hardness of the material to 200<=Hv<=250 as the above-described conditions. The resistance to pitting or environmental brittle cracking in high temp. water is improved by such setting of the conditions coupled with the above-described compsn.
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