Multidirectional Forging Uniformity Control And Quenching Residual Stress Reduction Process Research Of7085Aluminum Alloy Large Forgings

7085aluminum alloy is an aircraft structural materials with a series of excellent properties, such as high strength, high toughness and low quenching sensitivity.7085aluminum alloy has been widely used in manufacturing aircraft large main bearing structure. Multidirectional forging is the important way to improve the microstructure and mechanical properties of large overall component. However, as the forgings direction toward large-scale and integration, the problem of forgings organization uneven and quenching residual stress too large is serious,which is vulnerable to lead to forging performance unqualified. In this paper, process simulation and experimental research about multidirectional forging uniformity and quenching residual stress problem has been carried out around7085aluminum alloy large forgings. The main research contents include:(1)Using Deform-3D finite element simulation platform, the multidirectional forging forming process model of7085aluminum alloy large forgings has been established.The influence of the mold temperature on multidirectional forging forming uniformity of large forgings has been studied. The results show that When the mold temperature is in250℃～420℃, the higher mold temperature is, the better uniformity of the forging temperature is, when mold temperature is420℃, the average temperature of forging is445℃～, mean square error of temperature is5.82, when mold temperature is380℃, forging effective strain uniformity is the best, the average effective strain reaches6.4above, the equivalent strain mean square error is0.94.(2)Organization uniformity experiment of7085aluminum alloy forgings has been carried out, microstructure of7085aluminum alloy forgings has been analyzed by the Leica-DMI5000M metallographic microscope, the influence of the die temperature for the microstructure uniformity and the organization evolution of forging has been studied. The results show that when the mold temperature is in250℃～380℃, forging boundary area is not obvious recrystallization organization but fibrous tissue, when mold temperature is in400℃～450℃, the boundary of the forgings exists recrystallization organization, the percentage of recrystallization is smaller and grain size and distribution is not uniform, when mold temperature is in250℃～450℃, the center of the forgings occurred a large number of small uniform recrystallization organization. Improving the mold temperature, the evolvement mechanism of each part of the sample group tend to be more consistent, all area occurs dynamic recrystallization, which is helpful for improving the uniformity of the organization.(3)With the aid of finite element simulation software ABAQUS,7085aluminum alloy large forgings quenching process finite element model has been set up, quenching stress field and temperature field of large forgings has been studied. The results show that the intensity of cooling in each part of the forging is inconformity, forming the obvious temperature gradient, the biggest difference in temperature reaches200℃. forging residual stress changes in the quenching process. At the end of quenching, the core of the forging sustains tensile stress, but its edge sustains compressive stress. the maximum residual stress is along the length direction of the forging, the biggest tensile stress in the core of the forging is392MPa, the biggest compressive stress in the edge of the forging is-400MPa.(4)Using ABAQUS finite element simulation software,7085aluminum alloy forging die cold deformation simulation model has been set up, die cold deformation process was studied to reduce large forgings quenching residual stress. Results show that when the mold quantity was2%, the effect of reduction is better,the residual tensile stress in core and residual compressive stress in surface of the forging is reduced to-120MPa-120MPa, In two ways of the whole moulded and staging moulded, residual tensile stress in the core of forging are both reduced to less than100MPa. In the aspect of residual stress uniformity, the overall moulded is superior to the segmented mold.