A novel manufacturing process and validated predictive model for high strength and low residual stresses in extra large 7xxx panels

A novel manufacturing process, enabling the production of high quality i.e. with low and controllable residual stress RS distributions and good mechanical properties T section 7xxx panels, has been established. This process provides a solution to residual stress induced distortion problems, which greatly concerns a range of industries, especially the aircraft industry. This process consists of three sequential steps water quenching WQ , cold rolling CR and constrained ageing CA . The effectiveness of this process was experimentally verified through applying this process to laboratory sized 7050 T section panels. The RS was measured by neutron diffraction and X ray techniques, in addition to deflections and hardness at each processing stage. An integrated Finite Element FE model, including all three steps, was developed to simulate this manufacturing process and predict both the RS and the final strength distributions. It has been concluded that this novel process can effectively reduce the residual stresses from 300 amp; 8239;MPa to within 100 amp; 8239;MPa and produce T section panels with required mechanical properties i.e. hardness 159 amp; 8239;HV10 . A cold rolling level of 1.5 was found most appropriate. The residual stress and yield strength distributions were accurately predicted by FE, providing a valuable prediction tool to process optimization for industrial application