Study on U-bending Springback Behavior of GH4169 Ultrathin Strip
Ni-based superalloy GH4169 ultrathin strip was utilized as the research material,a constitutive model considering grain size and grain boundary was established.Compared with the stress-strain curves obtained by uniaxial tensile test,the model can well predict the flow behavior of GH4169 ultrathin strip with different thickness and grain size.In order to analyze the influence of material parameters and process parameters on the springback,U-bending test were carried out.The test results show that the springback decreases with the increase of grain size,material thickness and blank holder force,and the stamping speed has no significant effect on the springback.In order to compare the influence of grain size,strip thickness,blank holder force and stamping speed on springback parameters of U-bending test,orthogonal tests with four factors and three levels were designed.The numerical simulation of springback parameters of U-bending test was carried out by using the established constitutive model.The simulation results show that strip thickness has the greatest effect on springback,followed by blank holder force and grain size,and stamping speed has the least effect on springback.The grain size has a significant effect on the three springback parameters,while the thickness has a highly significant effect on the springback angle θ2 and the springback radius,but has no obvious effect on the springback angle θ1.The effect of blank holder force on the springback angle θ1 is the most obvious,and the effect of the springback radius ρ is the least obvious on the springback angle θ2.
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