Research On Liquid Forging Technology Of A356 Cast Aluminum Alloy

To solve the serious energy and environmental crisis in contemporary society,lightweight is one of the effective ways.Aluminum alloy,as one of the preferred lightweight materials,adopts the traditional way of casting and forging,have their own advantages and disadvantages,and the use of liquid forging,squeeze casting,can combine the advantages of both,satisfies the requirement of practical production effectively.In this paper,based on the liquid forging forming technology,A356 cast aluminum alloy as the raw material forming simple hub,was carried out on the solidification process of liquid forging forming numerical simulation and experiment,and the experiment the analysis of various parts,and finally to study the different elements on the microstructure and mechanical properties of the product,the influence of about the study of liquid forging forming technology and industrialization provides a certain theoretical and experimental basis.In this paper,ProCAST software was used to simulate the solidification process of hub parts.The results show that the solidification of the hub starts from the surface,and the center of the corner area is the final solidification area.The technological parameters suitable for the forming experiment range is: casting temperature is 680-720?,mold temperature is 200-300?,and the specific pressure is more than 200 MPa.In this paper,the effects of different forming methods and technological conditions on the structure and properties of the parts are studied.The factors that affect the structure and properties of the parts with different forming modes were the specific pressure applied during solidification,which increases the melting point of the alloy,the supercooling degree during solidification,and the nucleation rate.Therefore,the grains of the liquid forgings were smaller and denser and have better properties.EDS analysis of the product show that the main phase in the grain is ?(Al)phase and eutectic silicon at the grain boundary.The best technological parameters of the parts were: casting temperature 700-720?,mold temperature 250?,and pressure maintenance of 15-30 s.In this process,the microstructure of the products was mostly fine equiaxial crystals with relatively good and stable mechanical properties.The tensile strength,yield strength and elongation of the products before heat treatment were about 208.775 MPa,102.907 MPa and 8.581%,respectively.After T6 heat treatment,the eutectic silicon structure of the products had undergone great changes,the mechanical properties of the products had been greatly improved,the average tensile strength and yield strength increased by 36.4% and 125.5%,and the elongation decreased by 24.65%.Before heat treatment,ductile fracture was the main form of hydraulic forgings with good mechanical properties,while after heat treatment,ductile fracture was the primary cleavage fracture.In this study,it was found that the grain size of the product was closely related to the mechanical properties.When the eutectic silicon morphology did not change significantly,the grain size was smaller,which improved the distribution of silicon phase and grain boundary size,and improved the mechanical properties of the product.The morphology of eutectic silicon had a great influence on the mechanical properties of the products,the eutectic silicon with coarse morphology seriously reduced the mechanical properties of the products.After modification,the microstructure refinement effect of the product was significant.Eutectic silicon was modified into fibrous,and the mechanical properties were improved to some extent.Its elongation was 1.2 times of that before modification,and 10.33%.