The Effect of Different Friction Pressure on the Microstructural and Mechanical Properties of Ti Gr2 Titanium Alloy

Titanium alloys are used in many areas from aviation, aerospace and automobile industries to implant and prosthesis production with their high strength, high corrosion resistance and excellent fatigue strength. Having such a wide area of usage brings the necessity of joining titanium alloys, and the most used joining method is welding. However, when titanium alloys are joined with the traditional fusion welding method, brittle structure, resistance to high residual stresses and undesirable deformation problems are encountered due to uneven heating and cooling. For these reasons, in this study, titanium alloys were joined by friction welding via using applying different friction pressures, and then, macro- and microstructure studies as well as hardness, tensile and torsion tests were applied to the produced joints. As a result of microstructure studies, it was observed that the increased heat input due to the increased friction pressure caused the grains to grow, while increasing plastic deformation with increasing friction pressure prevented this growth and caused the grains to become thinner. In all welded joints produced, the highest hardness was obtained in the weld metal due to dynamic recrystallization caused by plastic deformation caused by friction. While it was determined that the tensile strength of the welded joints was close to each other, it was observed that the tensile strength of all samples was higher than the tensile strength of the base metal. Torsion test results were also close to each other, similar to the tensile test results.