Characterization and Evaluation of Microstructural and Mechanical properties of Friction Stir Welded Three Titanium Alloys
By
Kapil Gangwar, M. Ramulu, Daniel G. Sanders*
Abstract:
Titanium alloys- BOATI, TIMET-54M, ATI425, have been successfully joined by friction stir welding. Optimal welding parameters have been chosen such that there is no visible defect in the macrographs of the butt welds based on our work [1-3}. A refined microstructure, along with increased hardness, has been observed in the weld nugget, for all the three alloys. Furthermore, it has been observed that the microstructure evolved in the weld nugget, and the width of transition zone, are primarily dependent on the initial (parent or base) microstructure. The processing parameters were same for all the three alloys, however, the thickness of the sheets welded were different for all the three alloys. The widmanstattan plates decorated with prior beta grains have been observed in the weld nugget microstructure. Based on the experiments, however, subjected to a slight degree of error, ATI 425 has been observed to be the strongest, and BAOTI showed the lowest strength among all the three alloys. No visible trend has been observed for the retained percentage of beta in the weld nugget, for different thickness of sheet alloys have been welded in this investigation. However, based on the stress strain curve it can be concluded that ATI 425 shows better prospects among three alloys considered in the current study, correlating with the microstructure that consists of primary alpha infused with intergranular beta.
References
- P.Edwards and M. Ramulu, "Identification of Process Parameters for Ti-6Al-4V Alloy Friction Stir Welding" ASME Journal of Engineering Materials and Technology, Vol.132, No. 3, 2010, pp.031006-1to 031006-10
- D.G. Sanders, P. Edwards, A.M. Cantrell, K. Gangwar, M. Ramulu, "Friction Stir Welded Titanium Alloy Ti-6Al-4V: Microstructure, Mechanical and Fracture Properties", JOM, Vol.67, No.5, 2015, pp.1054-1063