Investigation of thermal fields, residual stresses, and tensile strength of dissimilar weldments of AA5052-AA7075 alloys on the stress corrosion cracking: Comparative analysis of coolant effects for enhancing weld integrity

This experimental research paper discusses the temperature fields, residual stresses, and welding strength of dissimilar welds between AA5052 and AA7075 Al alloys joined by Friction Stir Welding (FSW) and Tungsten Inert Gas (TIG) welding processes. The coolant condition during FSW, where the samples were welded with and without water, has been studied in detail to explore the cooling effects on the welded samples. Temperature profiles during welding processes were captured using Infra-Red Thermography (IRT), while the residual stresses in the weld zone were measured using X-Ray Diffraction (XRD) technique. Uniaxial tensile tests were carried out to evaluate the mechanical performance of the welded joints. The temperature measurements showed that FSW with water resulted in a peak weld zone temperature of 224 °C, FSW without water reached 321 °C, and TIG welding produced a higher temperature of 921 °C. FSW with water exhibited a compressive residual stress of 20 MPa, which is beneficial for weld strength and resistance to stress corrosion cracking. In other hand, FSW without water showed a tensile residual stress of 63 MPa, and TIG welding shown 30 MPa of tensile stress in the weld zone. The tensile strength of FSW with water was found to be the highest, 264 MPa, which is 16.4 % higher than that of TIG welding (223 MPa) and 22.2 % higher than that of FSW without water (216 MPa). This study shows the critical influence of coolant conditions on temperature, residual stress, and mechanical properties of welds, with direct relevance to aerospace, automotive, and marine applications where high-strength and corrosion-resistant joints are required.