| 简介 |
PROBLEM TO BE SOLVED : To provide a circumferential welding joint of a steel pipe having excellent inter-granular stress corrosion cracking resistance.
SOLUTION : When the circumferential welding joint is formed by butting ends of martensitic stainless steel pipes to each other and by carrying out the welding operation composed of multilayer welding passes in the circumferential direction, the composition of the steel pipe is limited to 0.010 mass% P. By this composition, the generation of the inter-granular stress corrosion cracking in the welding heat affected zone of the circumferential welding joint can be easily prevented. Further, it is preferable that the martensitic stainless steel pipes to be employed contain 0.015 mass% or less C, 0.015 mass% or less N, 10 to 14 mass% Cr, 3 to 8 mass% Ni, and an appropriate quantity of Si, Mn, S, and Al, and further contain one or more elements of 1 to 4 mass% Cu, 1 to 4 mass% Co, 1 to 4 mass% Mo, and 1 to 4 mass% W, one or more elements of 0.15 mass% or less Ti, 0.10 mass% or less Nb, 0.10 mass% or less V, 0.10 mass% or less Zr, 0.20 mass% or less Hf, and 0.20 mass% or less Ta, one or more elements of Ca, Mg, rare earth metal (REM), and B, and the balance of Fe and unavoidable impurities.
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