| 摘要 |
PROBLEM TO BE SOLVED: To provide a welded tube of low-C martensitic stainless steel, free from hot cracking in a weld zone and excellent in strength, toughness, and corrosion resistance. SOLUTION: A base material part is composed of a martensitic stainless steel which contains <=0.1% C and 8 to 15% Cr and where martensite comprises >=80% by area ratio. A weld metal contains <=0.1% C, (Cr content in the base material -0.5) to (Cr content in the base material + 2.0)% Cr, and 0.003 to 0.02% Ti, and further, Ni equivalent given by the expression: Ni+30C+0.5Mn and Cr equivalent given by the expression: Cr+Mo+1.5Si+0.5Nb are regulated to <=12% and 8 to 16%, respectively, and the relation between the Ni equivalent and the Cr equivalent satisfies inequality 0.4 (Cr equivalent -8)<=Ni equivalent <=1.5(Cr equivalent -8).
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