Mechanical and dimensional effect of laser welding process performed before and after plastic forming on titanium alloys

In this study; 98.9% purity of Grade 2 and alloyed Grade 5 (Ti-6Al-4V) titanium sheet materials (25x33x1 mm) were plastically formed at different temperatures like 25 º C, 500 º C and 850 º C. Plastic forming process was made by dividing the sheets into two different groups; The first group of sheets were firstly cut into two parts by guillotine, as the second step they were joined by laser welding method, then heat treated and finally plastic shaped. The second group of sheets were first heat-treated, then plastically shaped, then cut into two parts with the guillotine and finally laser welded. Heat treatment wasn't applied to the parts which would be plastically shaped at room temperature. In welding processes, the same type of parts are welded to each other as well as to different grade materials. As a result of these processes, parts of Grade 2 and Grade 5 were heat treated and welded together. One-Half these parts were welded before plastic forming and the other half parts are welded after plastic forming. To see the spring back rate, All parts were scanned by 3d scanning method and transferred to CAD environment in order to measure deviation from the nominal part and also to compare them to each other. Additionally, all samples complying with ASTM E8 standard have been prepared and tensile tests were performed. Again the results have been compared to each other. As a conclusion of all these analyzes, we have questioned if welding of heat treated titanium materials should be done before plastic forming or after.