High temperature mechanical properties of Inconel 718 pulsed Nd-YAG laser welds

Bead-on-plate full-penetration pulsed Nd-YAG laser welds were produced in 2mm thick sheets of Inconel 718 and were subjected to aging treatment with and without post-weld solution treatment at 980 degrees C. Weld microstructures, high temperature tensile and stress rupture properties were evaluated. The tensile and stress rupture properties of the welds after post-weld aging treatment were found to be inferior in relation to the base metal due to the presence of Nb-rich brittle intermetallic Laves phase in weld microstructure; however, the weld properties were found to satisfy the minimum property requirements generally specified for alloy 718 sheet products (AMS 5596). Post-weld solution treatment at 980 degrees C was found to result in considerable Laves dissolution and reduction in Nb segregation, leading to improvement in weld properties, although not to the level of base metal.