The physical model of the welding cycle for investigating the weldability of metals

Abstract

Welding cycle usually refers to thermal welding cycle (TWC) [1]. However, in any welding process with local heating the metal is subjected to plastic deformation initiating diffusion, the movement of vacancies, dislocations and grain boundary migration, leading to the microheterogeneity and changes of the final properties and weldability parameters. Consequently, simulation of the welding cycle in weldability tests designed for physical modelling the structure and brittle fracture must take into account not only the thermal but also deformation effects on specimens identical to the effects in welding. At present, poor weldability is usually found not in the weld metal but in the fusion zone characterized by changes of the composition, rapid grain growth and other parameters of the metal structure. Therefore, weldability tests of the parent metal are not carried out in welding and are instead carried out by simulating the welding cycle in specimens of the parent metal by electric resistance heating and deformation with a cycle similar to the welding cycle.