The Metal Flow Behavior Of 7075/7050 Aluminium Alloys During Hydrostatic Compression

The metal flow behavior of 7075/7050 aluminum alloys during hydrostatic compression was investigated by numerical simulation, mechanical analysis and experiments. The fundamental is given for the precision forging of complicated parts.The influence of the hydrostatic pressure was numerically made on the stress field and the metal flow behavior during compression was obtained. The results show that hydrostatic pressure has changed the stress field of the specimen and extended the forming limit, but it cannot change the deviator stress field and mean stress gradient. Thus, the hydrostatic pressure cannot influence the metal flow. Unsymmetrical pressure was superimposed on the inner wall of the ring specimen, and a different deviator stress field was obtained. The compression results show that the unsymmetrical hydrostatic pressure can remarkably change the metal flow.The hydrostatic compression process was analyzed by the principle stress method. The mechanism of the hydrostatic pressure was investigated, and the stress state of the cylinder and ring during hydrostatic compression was analyzed. The experiments of cylinder upsetting and ring hydrostatic compression were conducted. The results show that symmetrical pressure cannot change the figure of compression specimens, but the forming limit was extended. Ring compression with unsymmetrical polyurethane loading was conducted. The results show that unsymmetrical loading has remarkably changed the specimens figure and metal flow.The screw method ring compression experiments were conducted. The flow lines (figures of the screws) of the experimental results agree with the numerical simulation results very well. Therefore, the screw method can be used for precision investigation of metal flow behavior, and it provides a feasible way to study the metal flow behavior inside the deforming body.