Research On Experiment Of Superplastic Forming Of TC4 Laser Tailor-welded Blank

As aerospace products performance index is advancing ceaselessly, the trend of titanium alloy parts` large-scale is more and more obvious. Some titanium alloy parts` sizes are even more than the raw materials that manufacturers provide. Then titanium alloy blanks are welded to large-scale that parts require and then carries on the whole SPF or SPF /DB.The method can not only reduce the welding difficulty but also shorten the manufacturing cycle of titanium alloy parts.Laser welding is a kind of advanced technique of materials connection and usually laser welding parts` mechanical properties is similar to mother materials.This paper based on TC4 laser tailor-welded process, got high-performance laser tailor-welded blank. In 880℃and 900℃,author performed superplastic uniaxial tensile tests with TC4 laser tailor-welded blank,obtained mechanical properties of superplastic deformation. The result shows, when strain rate is between 10-4 and 10-2,flow stress curve is in a s-shaped shape;whenε& = 2.8 x 10-3s -1 , strain rate sensitivity index m = 0.58, achieves the maximum and is just a little smaller than the mother materials.Using finite element simulation software, in the conditions of temperature 880℃and strain rate 10-3 s– 1, author analyzed the 60°conical shells of TC4 laser tailor-welded blank`s superplastic forming process, won the conical shell`s forming pressure-time curves on constant strain rate.Using the pressure-time,carried on the TC4 laser tailor-welded blank`superplastic forming experiment and the obtained conical strain was -2.17. The result shows that TC4 laser tailor-welded blank`s superplastic forming performance is similar to mother. Analysis showed that with superplastic deformation, mother materials’s grains become coarse, weld’s wattle martensites become thick and secondary grains emerge. Finally, author discusses the influencefor TC4 laser tailor-welded blank `s superplastic forming properties. This study has carried on the beneficial exploration for the titanium alloy laser tailor-welded blank`s SPF and SPF/DB engineering application.