LAUSR

Thin sheets of UNS R30155 alloy with a thickness of 0.6 mm with AMS 5832 filler metal were welded using pulsed current gas tungsten arc welding (PC-GTAW). The aim of this research is to study the effect of frequency on the microstructure and mechanical properties of the joints. The results of the tests indicated that increasing the frequency up to the optimal level expands the region of fine equiaxed grains that contains equiaxed dendrites. It restricts the growth of epitaxial grains that contain columnar dendrites, resulting in an increase in the elongation, microhardness, tensile and shear strengths. Increasing the frequency causes uniform distribution of alloying elements in the weld metal, and increasing it more than the optimal level causes heterogeneity in the chemical composition and the formation of dispersed islands of equiaxed dendrites in the weld metal. Using non-pulsed current with higher heat input leads to the expansion of the epitaxial grains, which weakens the mechanical properties.