Effect of PCGTAW on the Inconel 690 alloy with respect to microsegregation attainment in comparison with the base metal processed with autogenous welding

Abstract

The mechanical properties and microstructure of weldments are always an imperative concern of researchers; therefore, the change from continuous gas tungsten arc welding (GTAW) to pulsed-current gas tungsten arc welding (PCGTAW) was investigated for alloy 690, using the autogenous welding method. The mechanical properties like the tensile strength and impact were examined for both variants (continuous and pulsed-current gas tungsten arc welding). The microstructure was the susceptible parameter, revealing a complete formation of the weldments. Hence, a complete analysis with an optical microscope of up to 400 μm and a SEM of up to 7000 μm was performed during the described examination. This analysis showed that the formation of the secondary phase was negligible in the case of the pulsed-current method, which was superior to the gas tungsten arc welding, exhibiting a tensile strength of 641 MPa and an impact strength of 66 J.