Effects of aging on impact behaviour of different stainless steel weldments

Instrumented impact testing was used to investigate the effects of aging on the impact deformation and fracture of different weldments of an AISI type 316L stainless steel plate and a superduplex stainless steel plate. Aging at 800 degreesC of metal inert gas (MIG) and laser beam (LB) weldments of t he 316L stainless steel plate produced a precipitation of sigma phase, whic h was more intense in the MIG weldments. Correspondingly, the MIG weldments showed a noticeable decrease in impact energy and in impact yield and maxi mum loads as the aging time was increased. The LB weldments, on the other h and, showed an initial decrease in absorbed energy followed by a noticeable increase, because of the appearance of delaminations during the fracture e vent. Aging at 900 degreesC of the parent metal and of LB and plasma arc (P A) weldments of the superduplex stainless steel plate produced a precipitat ion of sigma phase which was much more intense in the parent metal. Both th e parent metal and the weldments showed a noticeable decrease in impact ene rgy and in impact yield and maximum loads as the aging time was increased. These weldments were found to be more sensitive to the precipitation of sig ma phase than the austenitic stainless steel weldments.