| Abstract Scope |
The effects of multiple welding thermal cycles on Fe-10 wt.% Ni (10Ni) steel base metal heat affected zones (HAZ) were investigated to characterize the effects of peak temperature, cooling rate, and number of cycles on mechanical properties and microstructure evaluation. The 10Ni steel base metal is processed to promote a high-volume fraction of retained austenite. Characterizing the stability of the retained austenite phase in the HAZ, which are exposed to rapid heating and cooling during welding, is important for understanding any resulting local structure-property variations. SmartWeld software was used to generate predicted thermal cycles for welding heat inputs of 20 kJ/in. and 65 kJ/in. at peak temperatures associated with coarse grained (1350°C), fine grained (925°C), intercritical (725°C), and subcritical regions (550°C). A Gleeble 3500 thermomechanical simulator was used to apply combinations of the predicted thermal cycles that mimic what the base metal would experience during the fabrication of a multipass weld. The effects of the combined multipass weld thermal cycles were characterized using optical and electron microscopy, electron backscatter diffraction (EBSD), vibrating sample magnetometry (VSM), microhardness testing, and Charpy impact testing. |