Modification of grain refinement and texture based on pre-upsetting AZ31 Mg alloy in interactive alternating forward extrusion

Reducing energy consumption and exploring the potential of materials in depth is a long-term pursuit of goals and development directions in the field of extrusion technology. If load reduction and material performance can be achieved at the same time, this is a good strategy to solve the bottleneck. For the first time, a pre-upsetting technique was used before alternating extrusion in this investigation, which enhances grain refinement and increases the Schmid factor. This reduced the single grain yield strength and the load of the second process. The results of comparative research show that compared with interactive alternating forward extrusion (AFE), pre-upsetting alternate forward extrusion (UAFE) can significantly reduce the peak load required for forming, which increases the tensile strength of extruded AZ31 magnesium alloy products by 41.9% and the ductility to 23.7%. The average grain size was only 1/2 of the conventional alternating extrusion grain size, and the strength of the texture was weakened to 8.62. The increase in tensile strength is mainly due to fine-grained strengthening. Grain boundaries can hinder dislocation movement. Some grains are inclined from the original typical fiber texture to the ED direction during pre-upsetting, which effectively reduces the texture strength of UAFE and increases the ductility of the material. This provides scientific guidance and technical support for the development and application of high-performance magnesium alloy extrusion forming technology.