Effect of Different Post-weld Heat Treatments on the Microstructure and Mechanical Properties of Pulsed Nd:YAG Laser Welded Hastelloy C-276/Monel 400 Sheets
N. Sivagurumanikandan, G. Shanthos Kumar, S. Saravanan and K. Raghukandan
Post-weld heat treatment (PWHT) viz., annealing, normalizing and quenching was assessed regarding its effect on the microstructure and mechanical properties of pulsed Nd:YAG laser welded Hastelloy C-276/ Monel 400 dissimilar sheets. The weld zone (WZ) microstructures of the different PWHT specimens exhibit finer dendrite grains along with Crrich carbides and Ni-rich oxide precipitates. The weld joints subjected to quenching attains near equal microhardness of the as-welded condition. During tensile testing, failures occurred in the WZ for quenched and normalized weld joints, whereas the Hastelloy C-276 fractured in annealed conditions, exhibiting ductile fracture mode. In corrosion studies the WZ of the weld joint subjected to annealing imparted superior corrosion resistance.
Keywords: Nd:YAG laser, Hastelloy C-276, Monel 400, laser beam welding (LBW), post-weld heat treatment (PWHT), annealing, normalizing and quenching microstructure, mechanical strength