CORROSION RESISTING MATERIAL FOR HYDRAULIC POWER PLANT AND HYDRAULIC POWER PLANT USING THE MATERIAL

摘要

PROBLEM TO BE SOLVED: To provide sufficient corrosion resistance even in water of high corrosivity by containing Cr, Mo, S, C, and Fe at a specific rate in the anticorrosion material for a hydraulic generating plant. SOLUTION: At first, percentages showing the content of component elements are wholley set as percentages based on weight. An alloy is based on a stainless steel alloy containing Cr of over 18%. To this alloy, Mo of over 0.5% is added for improving corrosion resistance particularly pitting corrosion resistance. Further the contents of S and C are respectively limited to be under 0.01 and under 0.04, and the remaining are Fe and unavoidable impurities. Namely, when the alloy contains much S or C, the non-metallic inclusion such as MnS or the segregation part of C is generated. Hereby, when the alloy is placed in conductive water, by the potential difference between these part positions and the structure around them, the part positions providing the non-metallic inclusion and C segregation part are selectively corrodede to brake off and generate corrosion pits on the surface of material. Hence the contents of S and C are controlled.