Experimental investigation of titanium alloy powder reinforcement in GMAW mild steel lap joints

Gas metal arc welding (GMAW) is one of the most widely used fusion welding methods for mild steel in the industry. The use of reinforcing metallic powders, though common in friction stir welding, has not garnered much traction in GMAW. In this study, the application of titanium alloy powder and its effect on the microstructure and mechanical properties of lap welded AISI 1008 is discussed. Two groups of lap welded joints were created. One group was reinforced with Ti 6-2-2-2-2 alloy powder, while the other group was left unreinforced. A direct comparison of the two groups was conducted with respect to microstructural evolution, microhardness and tensile shear strength. This also included an XRD analysis to identify the phases present in the weld metal (WM) region of the weldments. The reinforcement of the lap joint weldments with Ti 6-2-2-2-2 alloy powder did not have any significant effect on its the tensile shear strength. However, an increase in microhardness in the WM region was observed in the reinforced samples. An observation of the microstructural evolution indicated that the promoted predominance of acicular ferrite in the reinforced samples, as well as intermetallic compound formations, contributed to the increased hardness in the reinforced samples. The results, therefore, indicate that this methodology could find applications in improving the microhardness of the weld joint.