Numerical Simulation And Procesee Investigation On Non-Isohtermal Extrusion Of TC4 Cup-Shape Part

TC4 (Ti-6A1-4V) alloy has comprehensively mechanical and machining properties and is the most widely used Ti ally, especially in aerospace and spaceflight. The conventional forming method for TC4 alloy is isothermal forming. Forging parts of TC4 alloy with precise dimension produced by general forging facilities and common dies lead to a decrease in cost and expansion of the application of titanium alloy.Backward extrusion process of TC4 cup-shape part was investigated in this study. Heat transfer process of forming process was explored. Cooling hard layer concept was introduced through temperature field computation. The reasons of large anti-stress and forming crack were also explained. It shows that the thickness of cooling hard layer is associated with the state of stress and heat preservation material by analyzing the heat transfer principle. It was proposed lubrication and heat insulation were key factors affecting part shaping by analysis of process parameters and simulation of temperature field. Influence factors were studied in detail by combining FEM numerical simulation with experiment. The full message of velocity field, temperature field, effective stress, effective strain and load-stroke curve was acquired thought numerical simulation. When there were lack of effective lubrication and heat insulation, it was affirmed by experiments that anti-stress was large, surface metal of billet didn't flow, life of die was short and cracks formed on surface of billet.Wrap extrusion reduces the thickness of cooling hard layer and improves the forming performance of TC4. The properties of wrap and billet were depicted by thermodynamics calculation and numerical simulation. Reasonable process parameters were determined for TC4 can-extrusion, which are useful for titanium alloy forming. Large anti-stress was reduced and life of die was elongated. Cracks and overlap rings on outer (or inner) surface of billet were minimized. It is an available process method for titanium alloy forming under the non-isothermal conditions.