Abstract: 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.

Abstract: 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.

Abstract: A radiographic test is conducted on a welded portion of a pipe or the like to form a radiographic image, which is introduced into a computer. Volumetric defects and planar defects in the radiographic image are emphasized and extracted by separate methods to obtain a volumetric candidate defect image and a planar candidate defect image. The candidate defect images are then combined to form a single image in which defects can be easily identified. Features of defects in the images are measured, and a set of interference rules is applied to the measured features. Each inference rule gives a degree of certainty that a defect is of a certain type. The degrees of certainty determined by a plurality of the rules are collated to obtain a total degree of certainty, and the type of a defect is inferred from the total degree of certainty.