Investigation On The Bending Springback And Residual Stress Of Al2024 Deformed With Non-Isothermal Dies

The stamping forming has been widely used in industry, but during the process some defects would come out, such as wrinkle,indentation,attenuation and springback, in which the springback is the hardest to control. The springback would cause the problems of low precision and hard assemble, so that it is necessary to research the issue deeply to improve the process. Aimed at the bending process of 2024 aluminum alloy, the non-isothermal bending process of blank forming at room temperature in high temperature mold was studied, that the springback and residual stress could be reduced without decreasing the mechanical properties of formed parts.The high temperature rheological behavior of 2024 Al at different temperatures and strain rates was studied, and the results show that the flow stress of 2024 Al would obviously decrease when the temperature rise up, while it nearly does not change with strain rates under 200? but conversely when above 200?.The non-isothermal bending of blank at room temperature and mold at high temperature and the isothermal bending were conducted. The results demonstrate the sprinback and residual stress of formed parts would fall down by increasing the temperature of mold or blank, and the springback could be decreased by increasing the holding pressure while increasing the holding time has not significant effects on the springback. When the blanks were heated to close temperature, the non-isothermal bending could get lower springback and residual stress than the isothermal bending.During the non-isothermal bending, the Vickers hardness of the blanks could maintain above 150 HV, while the Vickers hardness of the blanks by isothermal bending obviously decreased when the temperature raise up, which had only 75.4HV at 400?. The non-isothermal bending could get higher hardness and smaller grains than the isothermal bending.The simulations of bending process by MSC.Marc were conducted. The results shows that the non-isothermal bending could cause the blanks get larger plastic forming sot that the springback were smaller. The highest tensile stress and compressed stress of the deformed regions by non-isothermal bending were 10% lower than by isothermal bending, which verified the improvement effect of non-isothermal bending on the springback and residual stress.