Some studies on welding of AISI 304 stainless steel and oxygen free copper

Abstract

The present study investigates the effect of offsetting distance of welding arc in dissimilar material welding of AISI 304 stainless steel and oxygen-free copper C10200 using gas tungsten arc welding (GTAW) process. The joining of dissimilar materials using a fusion welding process is always a challenging task due to the difference in its chemical composition and physical-mechanical properties. The copper and iron elements are completely soluble in each other above their melting point temperature but there is limited solubility (less than 2 percent) at the low-temperature range. The excessive solubility of the element in each other produces hot cracks during the welding. The copper is difficult to weld because of high thermal conductivity which in turn tends to dissipate heat rapidly away from the weld causing difficulties in reaching their melting temperature. In addition, high thermal expansion may distort welding. Due to the differences in thermophysical properties, there is an uneven partitioning of the heat at the joint interface in dissimilar welding. To compensate for this heat loss and solubility of the elements at the interface between these weld materials, the welding arc was traversed at an offsetting distance toward copper. In this study, the offsetting distance was considered from 0.00 to 3.00 mm toward the copper using the GTAW process. To reveal the effectiveness of the weldments, these were characterized using metallurgical investigation which includes radiography testing, microstructure examination, and chemical element analysis (EDS). In addition, evaluation of the mechanical properties was exercised by tensile testing, fractography for fracture behavior, and microhardness with different offsetting distances. The finite element (FE) model was developed to study the thermal-mechanical behavior due to the offsetting of the welding arc in these dissimilar weldments.