| 摘要 |
PROBLEM TO BE SOLVED: To produce a superhigh vacuum and superhigh cleanness stainless steel small in emitting gas impurities and excellent in corrosion resistance by forming a passive film in which the surface layer on the outer side contains chromium oxide larger than iron oxide on the electrolytically polished face of a stainless steel. SOLUTION: In an austenitic or ferritic stainless steel, a passive film having a layer contg. chromium oxide larger than iron oxide on the outer surface is formed on the electrolytically polished face. Preferably, the outer surface contains no iron oxide and is composed of chromium oxide. Furthermore, the thickness of the passive film is preferably regulated to >=5nm, and the one, partcuarly, obtd. by subjecting a stainless steel to oxidation under heating at >=550 deg.C for >=9hr to form into >=13nm thikness preferably used. Moreover, the surface of the stainless steel in which the passive film is formed preferably has a flattening degree in which the maximum value of the difference in the height of ruggedness within the circumference of a radius of 5μm is regulated to <=1μm.
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