Microstructure and mechanical properties of friction stir processed TA5 alloy
(1. State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China;
2. Shandong Key Laboratory of Special Welding Technology, Harbin Institute of Technology at Weihai, Weihai 264209, China;
3. Luoyang Ship Material Research Institute, Luoyang 471000, China)
2. Shandong Key Laboratory of Special Welding Technology, Harbin Institute of Technology at Weihai, Weihai 264209, China;
3. Luoyang Ship Material Research Institute, Luoyang 471000, China)
Abstract: Ultra-fine grained TA5 titanium alloy was fabricated by friction stir processing (FSP). Temperature distribution and material flow were simulated by the coupled Euler-Lagrange (CEL) method. The microstructure and mechanical properties of TA5 alloy were characterized by optical and scanning electron microscope, Vickers hardness, and tensile tests. The processed alloy was composed of ultra-fine grained and equiaxed grains due to dynamic recrystallization. The microstructure recrystallized through grain boundary rotation and dislocation accumulation. The grain size reached the minimum on the advancing side of the stir zone with the highest grain misorientation. Ultimate tensile strength was promoted to over 830 MPa after FSP at a rotating speed of 200 r/min, whereas elongation varied a little. The specimens all fractured on the retreating side of the stir zone and smaller dimples were depicted from the fracture morphologies of FSP specimens.
Key words: friction stir processing; TA5 alloy; coupled Euler-Lagrange simulation; texture; mechanical properties