Microstructural and hardness modeling: Effect of multiple bead deposition in temper bead welding technique

摘要

Flux Cored Arc Welding (FCAW) process is often employed in industry where multiple welding sequences are used to produce stronger fastening between mating parts. Post Weld Heat Treatment (PWHT) is almost always recommended for relieving residual stresses and tempering the microstructural properties in order to prolong the fatigue and fracture life; however, it is often done away with due to the high costs involved, time constraints, infeasibility or sometime deleterious effects of the tempering process. This paper investigates whether the sequence of the initial deposition of the weld material itself can temper the microstructural properties and reduce the size of the Heat Affected Zone (HAZ) in the weld and parent metal. Four weld beads are deposited on a mild steel plate, with each being tempered by an overlapping bead using the Temper Bead Welding (TBW) technique. Numerical simulation is performed using FEA software VrWeld to evaluate the microstructure, hardness and size of the HAZ. It is concluded that there are significant improvements in the microstructure, hardness and size of the HAZ as a result of the deposition of the overlapping, tempering beads.