Research On Semi-solid Thixotropic Die Forging Of 7075 Aluminum Alloy Elbow

7075 aluminum alloy is an ultra-high-strength deformed aluminum alloy with a yield strength of more than 500 MPa,high specific strength and specific stiffness,good fracture toughness and corrosion resistance,excellent forming properties and environmental economic advantages for easy recycling.It still has strong competitive advantages for advanced materials such as titanium alloys,metal-based and polymer composite materials.It is one of the most important structural materials in the aerospace and transportation industry and has important research value.The shape of the elbow parts required for this study is relatively complicated,and the mechanical processing method has low production efficiency and low material utilization rate,which greatly increases the production cost;the traditional forging process is difficult to completely fill the entire cavity;the casting technology is used for forming,parts The strength is difficult to meet the requirements.In this case,the semisolid thixoforming technology can effectively realize the integration requirements of shape control and property control.In this paper,semi-solid billets were prepared by Strain Induced Melting Activation(SIMA)method.Based on this method,semi-solid billet preparation and thixotropic extrusion forming process of 7075-T6 aluminum alloy extruded rods were studied.In this paper,semi-solid billets were prepared by using 7075-T6 aluminum alloy.The grain size and roundness of billets under different parameters were studied by changing the isothermal processing temperature and time parameters.Then,using DEFORM-3D plastic forming simulation software,the forming process of elbow parts was simulated,and the influence of billet temperature,mold temperature,friction force,forming speed and billet shape on the forming process was analyzed.In this experiment,the semi-solid thixoforming experiments of elbow parts were carried out using different process parameters.The microstructure and mechanical properties of the parts at different positions were discussed and analyzed.Studies have shown that after heat treatment,at the billet temperature of 575 ° C,the elbows are thixoforming,the tensile strength of each part is above 450 MPa,and the highest tensile strength is 510 MPa.The substrate and the second phase were analyzed by SEM and TEM,and the influence of the strength of the second relative material was analyzed in combination with the tensile fracture.The experimental results show that the preparation of elbow parts by semi-solid thixoforming technology can improve production efficiency and have better mechanical properties.