Trailing heat sink effects on residual stress and distortion of pulsed laser welded Hastelloy C-276 thin sheets

A three-dimensional finite element model (FEM) was established to reveal the thermal-mechanical behaviors of pulsed laser welding (PLW) with and without trailing heat sink. Experiments were carried out to measure the welding temperature histories, residual distortions and solidification profiles. The simulation results agree well with the corresponding experimental measurements. The peak values of the temperature and transient longitudinal tensile stresses valleys in the weld increase as the cooling intensity increases from 5000 to 15,000 W/(m² K), while those of the temperature and transient longitudinal compressive stresses near the weld decrease. The peak values of the longitudinal residual compressive stresses and plastic strains, and the maximum deflections in longitudinal and transverse direction decrease as the cooling intensity increases from 5000 to 15,000 W/(m² K). The magnitudes of the transverse shrinkage distortions increase as the cooling intensity increases from 5000 to 15,000 W/(m² K). The proper cooling intensity to reduce the residual stresses and distortions of the PLW with the trailing heat sink is detected at 10,000 W/(m² K). The trailing heat sink is technically feasible for actual pulsed laser restraint welding in Hastelloy C-276 thin sheet structures.