MICROSTRUCTURE AND FATIGUE PROPERTIES OF DISSIMILAR SPOT WELDED JOINTS OF AISI 304 AND AISI 1008

Carbon steel and stainless steel composites are being more frequently used for applications requiring a corrosion resistant and attractive exterior surface and a high strength structural substrate. Spot welding is a potentially useful and efficient jointing process for the production of components consisting of these two materials. The spot welding characteristics of weld joints between these two materials are discussed in this paper. The experiment was conducted on dissimilar weld joints using carbon steel and 304L (2B) austenitic stainless steel by varying the welding currents and electrode pressing forces. Throughout the welding process; the electrical signals from the strain sensor, current transducer and terminal voltage clippers are measured in order to understand each and every millisecond of the welding process. In doing so, the dynamic resistances, heat distributions and forging forces are computed for various currents and force levels within the good welds’ regions. The other process controlling parameters, particularly the electrode tip and weld time, remained constant throughout the experiment. The weld growth was noted for the welding current increment, but in the electrode force increment it causes an adverse reaction to weld growth. Moreover, the effect of heat imbalance was clearly noted during the welding process due to the different electrical and chemical properties. The welded specimens finally underwent tensile, hardness and metallurgical testing to characterise the weld growth.