AUSTENITIC STEEL WELD JOINT

摘要

A weld joint having a base material and a weld metal both of an austenitic steel, wherein the weld metal has a chemical composition, in mass %, that C: 0.04 % or less, Si: 1.0 % or less, Mn: 3 % or less, P: 0.02 or less, S: 0.005 % or less, Cr: 15 to 25 %, Ni: 30 % or more, Mo: 10 % or less, Nb: 2.5 to 5 %, Al: 3.0 % or less, Ti: 0.5 % or less, and the balance: Fe and inevitable impurities, with the proviso that the contents of Al and Ti satisfy the following: (Ti + Al) > Nb/8, and wherein the base material has a chemical composition, in mass %, that C: 0.04 % or less, Si: 1.0 % or less, Mn: 3 to 30 %, P: 0.02 % or less, S: 0.005 % or less, Cr: 15 to 30 %, Ni: 5 to 30 %, N: 0.10 to 0.50% and further contains at least one of 10 % or less of Mo, 10 % or less of W, 0.001 to 1.0 % of V, 0.10 % or less of Al, 0.01 % or less of Ti, 0.01 % or less of Zr and 0.01 % or less of Hf, the balance being Fe and inevitable impurities. The weld joint is a high strength austenitic steel weld joint which exhibits excellent toughness at a low temperature and excellent resistance to hydrogen embrittlement, which are required for a piping and a vessel for high pressure hydrogen, particularly also in a welded zone.