Welded Structure made of low thermal expansion coefficient alloy and welding material therefore

摘要

In a welded structure and welded pipe, having members joined to each other by welding wherein, at least one of the members is formed of Fe-Ni-base low thermal expansion coefficient alloy, there is provided a welded structure and welded pipe having a weld metal free from cracking and achieving an excellent toughness and stress corrosion cracking resistance. Further, a welding material is provided which can form such a weld metal and is excellent in workability and weldability in fabrication. The weld metal comprises, on the weight % basis, Ni: 30 to 45%, Co: 0 to 10%, C: 0.03 to 0.5%, Mn: 0.7% or less, either one of or the total of Nb and Zr: 0.05 to 4%, and rare earth element: 0 to 0.5%, with impurities being P: 0.02% or less, Al: 0.01% or less, and oxygen: 0.01% or less, wherein each of Si and S satisfies the following formulas {circle over (1)} and {circle over (2)}, where each element symbol in the following formulas {circle over (1)} and {circle over (2)} indicates the content (weight %) of each element.Si<=0.1(Nb+Zr)+0.05% {circle over (1)}S<=0.0015(Nb+Zr)+0.0055% {circle over (2)}