Notched and unnotched tensile joint strength of AISI 52100–AISI 1015 using friction welding process
摘要
The present study investigates the effects of direct drive friction welding (DDFW) on the welded joint strength of AISI 52100–AISI 1015 steels. Three friction times were evaluated: 6 s, 8 s, and 10 s. A comprehensive analytical approach was employed, including macrostructure analysis, hardness testing, tensile testing, tensile fracture morphology analysis, energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD). Tensile tests were conducted on both notched and unnotched specimens with an effective diameter of 7.5 mm. The results observe the hardening region at the weld interface, with dimensions and hardness values varying with friction time: for 10 s, it measured 11 mm with an average hardness of 375 Hv10, and for 8 s, it measured 10.5 mm with an average hardness of 357 Hv10, while for 6 s, it measured 8 mm with an average hardness of 305 Hv10. That region size and hardness increased with longer friction times, indicating greater plastic deformation and strain hardening at higher friction durations. The UTS values for the unnotched specimens increase with increasing friction time: 203 MPa for 6 s, 250 MPa for 8 s, and 260 MPa for 10 s. On the other hand, the UTS values for the notched specimens show a relative increase with longer friction times but with the values in general below those of the unnotched specimens: 150 MPa for 6 s, 150 MPa for 8 s, and 180 MPa for 10 s. The unnotched welded samples showed the maximum strain with longer friction durations: 0.164 for 6 s, 0.279 for 8 s, and 0.237 for 10 s. For the notched samples, the maximum strain values also showed a slight upward trend: 0.098 for 6 s, 0.089 for 8 s, and 0.159 for 10 s. The tensile fracture surfaces exhibited a semi-ductile behavior with cleavage features at the weld interface. XRD analysis of the welded joints revealed a reorganization and high concentration of Feα (alpha ferrite) peaks at 110, 200, and 211. Reorganization and concentration of Fe3C (cementite) peak at 102. It also confirms significant thermo-mechanical deformation and grain refinement in the welded joints. EDS analysis confirmed that fracture occurred on the AISI 52100 steel side (stationary side), indicating localized failure in this region.