| 摘要 |
PROBLEM TO BE SOLVED: To provide a corrosion prevention method for preventing pitting corrosion, intergranular corrosion and stress corrosion cracking from occurring in a heat-affected zone of martensitic stainless steel and austenitic stainless steel, which are hard-faced with stellite. SOLUTION: This corrosion prevention method comprises: hard-facing the tip of a valve rod 3 of a safety valve 10, with the stellite 13 of a cobalt-based alloy; further hard-facing a hard-faced boundary 14 formed between the valve rod 3 and the stellite 13 so as to cover it, with a corrosion resistant alloy 15, wherein the corrosion resistant alloy 15 has a chemical composition containing, by wt., 0.10% or less carbon, 17.0-26.0% chromium, 40.0% or more nickel, 25.0% or less iron, 2.5% or less tungsten, 6.5% or less silicon, 3.5% or less manganese, 10.0% or less molybdenum, 5.5% or less niobium and tantalum in total, 1.15% or less titanium, 0.8% or less aluminum and 1.0% or less boron. COPYRIGHT: (C)2006,JPO&NCIPI
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