AUSTENITIC STEEL WELDED JOINT

摘要

An austenitic steel welded joint is produced by welding base metal of austenitic steel having a certain chemical composition with a gas tungsten arc welding process which uses welding material of austenitic steel having a certain chemical composition. A chemical composition of weld metal comprises: C <= 0.1%; Si<= 0.8%; Mn: 1.5 to 5.5%; Ni: 8 to 15%; Cr: 18 to 24%; Al < 0.05%; N: 0.15 to 0.35%; and one or more of V <= 0.5%, Nb<= 0.5%, and Mo<= 4.5% if necessary, the balance being Fe and impurities that contain O<= 0.02%, P<= 0.05%, and S <= 0.03%, and this chemical composition satisfies [413 - 462(C + N) - 9.2Si - 8.1Mn - 13.7Cr - 9.5Ni - 18.5Mo <= -70]. The amount of ferrite of the weld metal is 20% or less in area ratio. The austenitic steel welded joint has both high strength and excellent hydrogen embrittlement resistance which are properties required in high-pressure hydrogen gas piping in the case of carrying out no postweld heat treatment.