The issue of tracking residual stresses initiation in welding copper under various affected conditions is essential in increasing safety through improving the welding quality in particular, in the nuclear industry. This study investigated the behavior of welded copper numerically and experimentally under contact-heating compression test with constant clamping force. The scanning contact potentiometry (SCP) method was used to track the initiation and development of residual stresses within the weld zone. Furthermore, the finite element analysis (FEA) method was used to simulate and study the effect of thermal variations, with a constant compressive force, on mechanical factors that contribute to residual stresses formation within the weld zone. Additionally, scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) were used to get further information about the topography and composition of the specimen's surface. SCP results show that residual stress initiated from within the volume after 200 °C, and with further oxidation, its formation began on the surface after 250 °C. Using the relationship between maximum values of linearized von Mises stresses and maximum values of ADS at high SLS = 4.523, it was found that residual stresses generation began after 150 °C within the weld zone, and thermal stresses linearly increase with temperature due to further thermal expansion, which is associated with variation in linearized von Mises stresses and ADS maximum values. Comparison between potentiograms after 300 °C and FEA results have shown that the distribution of von Mises stress, normal stress, and total deformation are matching those in the distribution of ADS and are localized within the weld zone. HIGHLIGHTS The behavior of welded copper under compression at medium-low temperature range Residual stresses detection at an early stage localized within weldment zone Residual stresses increase with increased oxidation at copper surface Matched the SCP Experimental and FEA simulation results GRAPHICAL ABSTRACT

The issue of accurate identifying in advance structural nonhomogeneities of metals is one of the main factors in improving the manufacturing efficiency and safety during service. This paper illustrates the conventional uni-axial tensile test that is carried out on the diffuse and localized necking stages of dog-bone shape lead specimen. The scanning contact potentiometry method was used to locate the rupture zone. Infrared radiation was used to heat the specimen up to 40°C, in order to excite structural nonhomogeneities in the bulk of the tested specimen. It was found that the infrared radiation increases the predictable nonhomogeneity zone. A ductile rupture occurs in the same nonhomogeneity zone that was previously exactly identified using the scanning contact potentiometry method. The formed diffused necking was observed to initiate from the right where the rupture spread diagonally, at an angle of 70° between the tensile axis and the rupture plane. However, the angle between the tensile axis and the hexagonal singular reflex plane was 69°, which was slightly different from the rupture angle. Both results of the rupture angles of the tensile test and the SCP are relatively matching and diverse from the theoretical calculations. The results shown in this work highlight the importance and the efficiency of the experimental SCP method in prediction of the material failure behaviour.