Failure Analysis of Cu-DHP Joining Processes: A Comparative Study of FSW and SFSW Techniques

Abstract This article presents a failure analysis conducted on specimens extracted from 2.5 mm sheets of Cu-DHP (Cu99), which were joined using friction stir welding (FSW) and submerged friction stir welding (SFSW) processes. To evaluate the performance of the welded joints, destructive and non destructive tests, including tensile tests were performed. Additionally, morphologic analysis using scanning electron microscopy (SEM) combined with energy dispersive X-ray (EDX) and fractography investigations were carried out on the samples. The results of experimental research show refined microstructures both for FSW and SFSW welding. Improved mechanical properties have been obtained for SFSW welding, compared to FSW. SFSW specimens demonstrates superior tensile strength and a higher hardness compared to FSW specimens, by performing joining process underwater. The fracture surfaces of the tensile test specimens from the base material (BM), FSW and SFSW joints, revealed the ductile fracture mechanism of the joints. EDX analysis confirms compositional integrity of the base and welded metals. Results highlights suitability of the FSW and SFSW processes for joining of copper Cu-DHP.