Characterisation of residual stress state in laser welded low carbon mild steel plates produced in keyhole and conduction mode

Characterisation of residual stress state was performed in 4 mm low carbon steel plates laser welded in keyhole and conduction mode. Residual stress characterisation was carried out at the ENGIN-X strain scanner at ISIS (Oxford, UK). It was shown that although the maximum magnitude of tensile residual stress is similar in welded specimens manufactured under different welding modes, the distribution profile is quite distinguished. The conduction welding mode resulted in a larger tensile stress domain as compared to the keyhole mode in the longitudinal direction. This also resulted in a different magnitude of balancing compressive residual stress field. Understanding of such different stress profiles is important for application of such advanced welding processes in joining of design efficient structural material.