Ageing Effects on Room-Temperature Tensile Properties and Fracture Behavior of Quenched and Tempered T92/TP316H Dissimilar Welded Joints with Ni-Based Weld Metal

The present work is focused on the investigation of isothermal ageing effects on room-temperature tensile properties and the failure of quenched and tempered martensitic/austenitic weldments between T92 and TP316H heat-resistant steels. The dissimilar weldments were produced by gas tungsten arc welding technique using a Ni-based Thermanit Nicro 82 filler metal. The welded joints were subjected to unconventional post-welding heat treatment consisting of the welds solutionizing (1060 °C/30 min), followed by their water quenching and final stabilization tempering (760 °C/60 min). The treatment was completed by spontaneous air cooling within a tempering furnace. The welds in their initial quenched and tempered condition were subsequently aged at 620 °C for up to 2500 h. Apart from room-temperature tensile tests performed for all the welds material states, additional cross-weld hardness measurements were carried out on longitudinal sections of broken tensile specimens. The applied thermal exposure resulted in recognizable deterioration of plastic properties, whereas their effects on strength properties were rather small. The welds tensile straining and fracture evolution exhibited competitive behavior between the austenitic TP316H region and Ni-based weld metal. The observed failure locations showed significant hardness peaks due to intensive, necking-related strain hardening effects occurred during the tensile tests.