Research On Hot-press Forming Technology And Quality Control Of Ti55A Funnel-shaped Parts

Ti55A is a kind of titanium alloy which can withstand higher service temperature.The research on the relative properties of Ti55A is relatively few,and the research on the manufacturing process of Ti55A sheet is far from enough.In this paper,a Ti55A material skin product applied in spacecraft is used as the research carrier,the high temperature formability and high temperature rheological property of Ti55A titanium alloy sheet with 1.5thickness were investigated by high temperature tensile test at 750?840?and strain rate 0.0005^-1?0.01S^-1,the power dissipation diagram and instability diagram of Ti55A material are drawn by analyzing and fitting the experimental data,and then the thermal processing diagram is obtained.By superimposing different strain hot working drawings,a more general working area can be obtained.By designing two kinds of hot pressing forming schemes,a safer forming process interval in the hot working drawing can be adopted.Through numerical simulation analysis and hot-pressing test,the forming effect of different schemes was compared,and the effect of transition surface design and blanking size on sheet wrinkling and tearing was analyzed.The mechanical properties and metallographic structure changes of the material and the original sheet after forming,and the mechanical properties and metallographic structure changes of the products at different positions after forming are compared and analyzed,the quality control was analyzed by measuring the surface precision and thickness distribution of the formed products.It is found that the flow stress of Ti55A material is obviously affected by temperature and strain rate at high temperature.The flow stress increases with the increase of strain rate and decreases with the increase of deformation temperature when the strain rate is constant.The results show that the high temperature stability of Ti55A can be improved by processing Ti55A material in the range of 775?825?and strain rate 0.0005S^-1?0.01S^-1.For the Ti55A structural part with funnel shape,the wrinkle and tear tendency can be effectively alleviated by increasing the twice hot pressing of the transition surface,and the forming quality can be changed by changing the shape of the blank and designing the process port.The tensile strength of Ti55A is related to the change of strain at different positions.The increase of strain can make the grain refinement and equiaxed degree of Ti55A increase.