Study On Forming Technology Of TA15 Titanium Alloy Large Scale Thin Web Forging

TA15 is a high aluminum equivalent near ?-type titanium alloy,with high strength,low density,strong corrosion resistance and good welding performance.It has been widely used in the field of aerospace.However,TAl5 titanium alloy hot processing window is narrow.So it is difficult to form.In this paper,the hot deformation behavior of TAl5 titanium alloy was studied by isothermal compression experiment on TA15 titanium alloy material for large-scale aerospace thin web forging.The process parameters(forging temperature,die temperature and forging speed)of forming for large-scale aerospace thin web forging were studied by finite element numerical simulation.The residual stress value and the distribution law of the forging at different annealing temperatures were studied by numerical simulation and experimental measurement.The main conclusions are as follows:(1)Hot deformation behavior of TA15 alloy was studied by the experiment of isothermal compression.The constitutive equation of the Z parameter containing Arrhenius term is ?=165.29ln{(Z/8.228×1021)1/4.3145+[(Z/8.228×1021)2/4.3145+1]1/2}.The primary a grains size decreases with increasing deformation temperature when TA15 deformation temperature range of 750? to 980? and the strain rate of 0.1s-1.The width and thickness of the "necklace" structure formed by the new a grains increases with increasing deformation temperature.The a grains size decreases with increasing strain rate when TA15 deformation temperature is 900? and strain rate from 0.001s-1 to 1s-1.Deformation of 50%of the a grains size is smaller than deformation of 10%of the a grains size when TA15 deformation temperature is 950? and strain rate from 0.1s-1 to 1s-1.The reasonable hot deformation process parameters range of TA15 titanium alloy rang from the temperature of 850? to 980?,with strain rate of 0.01-0.1s-1.(2)The forging temperature,die temperature and forging speed of forging were studied by numerical simulation technique.The resuls show that forging forming force decreases with increasing forging temperature(810,860,910 and 960?).The forging forming force tends to fluctuate with the increase of die temperature(250,300,350 and 400 ?).Variable speed forging can effectively reduce the forging forming force.The forging temperature of 960?,the die temperature of 300? and the initial speed of 25mm/s non-uniform speed forging process were selected by the process optimization.The forging pressure can be controlled at 70,000 tons to meet the requirements of forging forming process.The forming effect of forging in 80,000 tons of press to meet the requirements of forging forming process.(3)The residual stress value and distribution law of forging were studied by numerical simulation.The residual stress of the forging decreases with the increasing annealing temperature when the annealing temperature of remove the residual stress ranges form temperature of 800 to 900?.The residual stress decreases greatly and distribution is more uniform after annealing.The residual stress in the X direction on both sides of the forging is tensile stress,and the residual stress in the X direction between the two sides is compressive stress.The residual stress of forging is measured and studied by blind-hole method after annealing.The residual stress in the X direction is between-107 and-25.7MPa after 850? annealing.The residual stress on the front side of the forging is greater than the residual stress on the back.