Tensile joint strength characterizations for Cr-Ni-Mo steel (AISI 316) during direct drive friction welding process

The present study aims to investigate the effect of the mechanical and metallurgical joint strength behavior of Cr-Ni-Mo steel (AISI 316) using direct drive friction welding. Experimental procedures in the study included macrostructure, microhardness, tensile test specimens with effective diameters of 4 mm, 6 mm, and 8 mm, microstructure of the fracture position, and tensile fracture morphology. The results concluded that the average microhardness values for 4 mm, 6 mm, and 8 mm diameter around the weld interface center are 298 Hv 0.1 , 300 Hv 0.1 , and 295 Hv 0.1 , respectively. The ultimate tensile strength ratios were of 95%, 98%, and 97% for 4 mm, 6 mm, and 8 mm, respectively, while, the ductility increased with the diameters of 41%, 50%, and 57% for 4 mm, 6 mm, and 8 mm, respectively, compared to AISI 316. The fracture position for all welded joints was in the adjacent region to the interface. The fracture surfaces had a fingerprint form and ductile mode at cleavage features. The center of the fracture revealed different forms of dimples and microcavities collected at that center.