Research On Liquid-solid Pressurized Casting Forming Of A356 Aluminum Alloy Automotive Wheel Components

At present,the domestic production process of aluminum alloy automobile wheels is mainly gravity casting and low-pressure casting,both of which have advantages and disadvantages.Gravity casting has low cost but poor casting quality,and low-pressure casting casting has good quality but high cost.Based on this,based on the traditional gravity casting,this study proposes a new process of liquid-solid pressure casting?LSPC?.During LSPC process,wind pressure and mechanical pressure were applied at the key position of the hub,on the one hand reduces the riser ratio and improves the material utilization rate of the hub;on the other hand,during the solidification process of the aluminum alloy hub,the applied wind pressure and mechanical pressure The pressure can play the role of compulsory shrinkage,thereby improving the quality of castings.In order to explore the influence of process parameters on microstructure and mechanical properties of the formed parts and obtain optimal process parameters,numerical simulation LSPC of A356 aluminum alloy wheel were performed.In addition,heat treatment of alloy wheels formed by LSPC was also carried out to investigate its influence on microstructure and mechanical properties.First of all,in this thesis,we simulated the filling and solidification process of liquidsolid supercharged A356 aluminum alloy wheels through ProCAST software,and the the temperature field,effective stress field and defects of the hub casting in the simulation process were analyzed.At the same time,the range of the above process parameters was determined,which provided a basis for the subsequent forming experiment.Secondly,in this paper,through multiple sets of orthogonal experiments,the influence of different process parameters on forming quality is compared and analyzed.The results show that in terms of mechanical properties,the improvement effect is remarkable.The No.14 sample(T_pouring= 710 ?,T _{upper die} = 340 ?,T_{side die} = 360 ?,T _{lower die} = 400 ?,P_{wind pressure} = 0MPa,P_{mechanical pressure} = 1.4MPa)exhibited the best mechanical properties including yield strength of 112.61 MPa,tensile strength of 215.48 MPa,elongation of 12.86%.In terms of organization,with the addition of local pressure,the shrinkage and shrinkage defects are significantly reduced,and the local tissue morphology has also been improved to a certain extent.In addition,in this study,the tensile strength was used as the criterion,and the orthogonal experiment range analysis was used to determine the optimal process parameter combination for this forming experiment,namely T _pouring = 710 ?,T _{upper die} = 330 ?,T_{side die} = 350?,T _{lower die} = 390 ?,P_{mechanical pressure} = 0.4MPa,t _{mechanical pressure intervention} = 12 s,P _{wind pressure} = 0MPa.Finally,in this thesis,we investigated the effect of solid solution and aging process parameters on the microstructure mechanical properties of shaped parts.The microstructure morphology of ?-Al before and after heat treatment did not change much,but the eutectic silicon phase changed more than before heat treatment,mostly in the form of small short rods,and its distribution was relatively uniform.In terms of mechanical properties,take the best performance the No.6 sample(T_solution = 540 ?,t?_solutio = 350 min,T_aging= 150 ? and t_aging = 162min)as an example,its yield strength is 160.49 MPa,tensile strength The strength is 256.36 MPa and the elongation is 12.43%.Compared with before heat treatment,its yield strength increased by 47.88 MPa,an increase of 42.52%;ultimate tensile strength increased by 40.88 MPa,an increase of 18.97%;elongation decreased by 0.43%.At the same time,this study also conducted range analysis and analysis of variance on the heat treatment orthogonal experiment results,and established the optimal parameters,named T = 550 ?,t = 290 min,T = 150 ?,T = 162 min.