The Numerical Simulation On Press Forging Process Of Train Valve Of Inconel751 Alloy

Inconel751 alloy is used to produce valve of heavy-duty engine by the electrical upsetting and press forging technology which is very complex. Comparing with traditional free forging technology, it improves the productivity and utilization efficiency of materials. But the technology is not mature, the main problem is neck rupture because of coarse grains. So the hot deformation behavior and press forging process of Inconel751 alloy are investigated by using physical and numerical simulations, the source of problem was confirmed, furthermore, the grain will be smaller by direct aging heat treatment.The flow behavior and dynamic recrystallization were investigated by using hot compression tests. The influence laws of deformation rate and temperature were analyzed. Based on the experimental data and quantitative metallography, the relationships between hot deformation activation energy, peak stress, dynamic recrystallization grain size, and Zener-Hollomon parameters are obtained, meanwhile, the dynamic recrystallization graph of hot deformation was drawn .Based on MARC /Autoforge3.1 software, the modeling process of Inconel751 alloy valve was analyzed, the variations of temperature, strain, stress, deformation force and recrystallization grain size among process were observed. The main cause of coarse grain of valve neck resulted from the initial grain size. There are identical for microstructure between modeling results and manufactured valve. Through changing the initial grain size, based on the simulation results, it will remove the coarse grain by changing the initial grain size which is less than 15μm.In order to get fine grain, the direct aging heat treatment was taken. the experimental results show that direct aging will improve the tensile property in room / high temperature and shock strength in room temperature comparing with standard heat treatment, but the rupture time in high temperature decreased.