Metallographic and Microstructure Analysis of Gas Tungsten Arc-Welded Bimetallic Copper-to-Stainless Steel Joints

The steel-copper dissimilar material joining is obtained by gas tungsten arc welding process at different current levels. High Ni-based filler material is used due to its compositional solubility into both Cu and SS aiming to achieve better joint consolidation. The joint is examined on the scale of tensile test, microstructural analysis, microhardness, scanning electron microscopy, and energy-dispersive x-ray spectroscopy. The highest tensile strength of 179 MPa at 150 A current is obtained. On the other hand, defect-free joint of steel-copper at all the parametric conditions is achieved. The post-tensile fracture surface morphology showed a dimple-like structure; the microhardness levels are in the range of 103-228 Hv for fusion zone. The joint assessment indicated successful dissimilar material joining. However, the unmixed zone and partially melted region are identified near the SS/weld metal interface. The mentioned zones are the function of current levels, whereas the tensile property reported marginal variation in the values with the change in current levels. Moreover, defect-free sound joints can be obtained at exploited current levels.