Experimental investigation of rotary friction welding on the mechanical properties of NiTinol alloy

In this research work, super elastic nickel-titanium alloy (NiTinol) rods were joined using a fully automated direct-driven rotary friction welding technique at various rotational speeds, namely 1800, 1900 and 2000 rpm. Mechanical properties such as tensile strength, flexural strength, impact strength and microhardness were determined for as-welded, heat-treated and cryogenic-treated welded samples. Research findings revealed that maximum tensile strength of 1112 MPa is observed which is more by an amount 27.94%, 37.15% and 36.83% at 1800, 1900 and 2000 rpm for heat-treated samples. A significant increase in flexural strength of 3.29 kN/mm2 was achieved which is 31.58%, 26.32% and 27.78% higher, and a high impact strength of 0.8 N-m/mm2 which is 57.15%, 55.55% and 54.55% higher, respectively, for heat-treated samples. The highest microhardness of 347 HV was recorded for cryogenically treated samples at 1900 rpm which is 7% and 4% more compared to heat-treated and as-welded samples.