Structure and Mechanical Properties of the Welded Joints of Large-Diameter Pipes

The structure and mechanical properties of the technological welded joints of large-diameter pipes of strength class K60 produced by two companies are studied. Along with standard mechanical properties (sigma(0.2), sigma(u), delta, psi), specific work of deformation a (tensile toughness) and true rupture strength S-f are estimated from an analysis of the stress-strain diagrams constructed in true coordinates. The mechanical behavior is found to be different for samples cut from different zones of a welded joint (central weld, heat-affected zone, and base metal). The mutual correlation between parameters a, S-f, and impact toughness KCV is considered.