Flow behavior and stress analysis of materials during canned hot extrusion process of dissimilar alloys

Flow behavior of the core and the canning of materials during canned hot extrusion was investigated using FEM and validated by industrial test. The results show that several stages of the extrude process are concluded based on both the extrusion force vs. stroke curve and the features of materials flow behavior, which were simulated by FEM. The stage of the core steady flow is of more importance, in which the length and the radius of the core directly determine the bar yield and extrusion ratio. The stress analyses were made in typical locations in cross section of the billet and thus vector distribution of stress state were pictured and the strain type and complexity were quantitatively characterized using Lode parameters. Furthermore, the method calculating the extrusion ratio was proposed and the effect of yield stress on flow behavior and extrusion ratio was illuminated. The comparison result shows that the thickness of the canning obtained by FEM is in well agreement with that in industrial test.