Research On Microstructure And Mechanical Properties Of Aluminum Alloy Flywheel Housing Formed By Squeeze Casting

Squeeze casting is a kind of technology that applies a certain amount of pressure in the forming process of components to achieve good performance.It combines the advantages of forging and casting,and it can meet the use needs of complex high-performance load-bearing structural parts.In this paper,based on squeeze casting technology,the forming technology of engine flywheel housing with ZL104 aluminum alloy as raw material is studied.In this paper,the numerical simulation of the forming process of the flywheel housing,the forming experiment of the flywheel housing and the heat treatment of the flywheel housing are studied.In this paper,ProCAST software is used to simulate the filling process and solidification process of flywheel housing under 16 groups of different specific pressure,holding time,pouring temperature and mold temperature,which provides the analysis means of temperature field,stress field and defects field of flywheel housing components for subsequent forming experiments.The results show that:under 16groups of simulation conditions,the mold filling of aluminum alloy flywheel housing casting is complete,and there is no underfill phenomenon.The final solidification area of casting is mainly in the runner,and the average equivalent stress of flywheel housing formed under higher specific pressure and lower die temperature is larger.In this paper,the forming experiments of flywheel housing were carried out by 16groups of orthogonal experiments,and the mechanical properties and microstructure properties of the castings under different experimental conditions were analyzed.The results show that:Based on the ultimate tensile strength(UTS)and elongation,through comprehensive analysis,the best process parameters are as follows:the pouring temperature is 655?,the mold temperature is scheme B(the bottom die temperature is160?,The upper die temperature is 170?,the left die temperature is 160?,the right die temperature is 130?),the pressure holding time is 20 s and the specific pressure is34.00 MPa.Under the optimal process conditions,the average ultimate tensile strength(UTS)and the average elongation of the flywheel housing are 211.17 MPa,and 7.7%.The ultimate tensile strength(UTS)and elongation reached a better level.In terms of organization,the microstructure is mainly composed of?-Al phase and Al-Si eutectic phase.At the local compression position,the microstructure is compressed along the direction of the compression pressure.When the process parameters are selected properly,the structure and properties of the parts are good,and the defects are less.Except for Al,Fe,Mn and Si are mainly enriched on the grain boundary.In this paper,the effects of solution treatment and aging treatment on the mechanical properties and microstructure of flywheel housing were studied by controlling a single variable.The results show that the ultimate tensile strength(UTS)and yield strength of the flywheel housing after heat treatment are obviously improved,and the elongation is decreased.Under the condition of heat treatment in experiment 17(The solution temperature 530?,the solution time is 180 min and the aging temperature is 175?,the Aging time 300 min),the mechanical properties of aluminum alloy flywheel housing are as follows:ultimate tensile strength(UTS)is 280.03 MPa,yield strength is 210.17 MPa,and elongation is 4.6%.Comprehensive analysis of mechanical properties,the optimal process parameters of heat treatment are:the solution temperature 540?,the solution time is 180 min and the aging temperature is 175?,the Aging time 300 min.In the aspect of microstructure,heat treatment can make eutectic silicon of flywheel housing change from long fiber shape to short rod shape and spherical shape,and precipitate needle shape?``-Mg₂Si strengthening phase and discoid phase?-Mg₂Si strengthening phase,which is the main reason for the improvement of casting properties.