Numerical Simulation On 6082 Aluminium Alloy During Equal Channel Angular Pressing

Al-Mg-Si(6xxx series)alloy is one of the most commonly used automotive aluminium alloys.With the development of the automotive industry,it is important to select the appropriate processing technology to optimize the performance of Al-Mg-Si alloy.Refining the grain is an effective means to improve the material properties.Equal Channel Angular Pressing(ECAP),as a kind of severe plastic deformation technology with unique advantages in refining grains.The effect of refining Al-Mg-Si alloy grains is related to the magnitude and distribution of stress field,strain field and temperature field during ECAP.The size and distribution of these fields depend on the ECAP die structure and deformation parameter,so study of the influence of different parameters comprehensively on the ECAP deformation process is of great significance for the preparation of ultra-fine grain aluminium alloy materials by ECAP.In this paper,the ECAP process of 6082 aluminium alloy was studied by numerical simulation and experiment.Firstly,the influence of die structure and process parameters on the ECAP process of 6082 aluminium alloy was studied by numerical simulation.The multi-pass simulation was carried out to obtain the strain accumulation law of the ECAP process of 6082 aluminium alloy with obtained die structure and process parameters.The 6082 aluminium alloy was pressed once and analyzed,and the microstructure,mechanical properties and texture distribution of the 6082 aluminium alloy before and after ECAP deformation were analyzed based on numerical simulation.The main results are as follows:(1)The influence of the die outer corner and the die inner angle on the deformation of the 6082 aluminium alloy during the ECAP defromation process was analyzed by numerical simulation.When the inner angle was 90°,the degree of shear deformation,effective strain,and pressing load were decreased with the increase of die outer angle.With the increase of the die inner angle,the deformation is more uniform,but the deformation strain is small and cannot be accumulated bigger strain.It is concluded that when the die inner angle is 900° and the die outer angle is 25°?37°,the 6082 aluminium alloy has a large deformation with good uniformity of strain distribution.(2)The effects of different friction models(Coulomb friction model and Shear friction model)and deformation temperature on deformation behavior,strain distribution and load during deformation of 6082 aluminium alloy were analyzed by numerical simulation during ECAP.With the increase of friction factor,the form of angular gap decreased,and the uniformity of the effective strain but the pressing load value increases significantly during deformation process.The shear friction model was used to evaluate the effect of friction factor on 6082 aluminium alloy during ECAP.It is concluded that when the temperature raised from 20? to 350?,the cross section effective strain of 6082 aluminium alloy was increased,but the deformation homogeneity was decreased at 370?,and the average effective strain value was the largest at 350?.(3)The influence of four different typical pressing paths on 6082 aluminium alloy during ECAP was illustrated.Under different paths,the radial strain accumulation direction of the sample is different.After four passes of pressing,6082 aluminium alloy had good deformation uniformity in the route BC,and average effective strain reached maximum in the route C.The pressing load had no significant changes with multi-pass and different routes during the simulation.(4)The grains of 6082 aluminium alloy was elongated along the pressing direction and the microstructure was refined after one pass ECAP.The tensile fracture surface of the specimen after one pass ECAP is shear-type(45°)fracture.The strength and plasticity of 6082 aluminium alloy were increased after one pass ECAP.The strength and plasticity of the 6082 aluminium alloy were improved;the shear texture of the sample was enhanced after one pass ECAP.The experimental results are consistent with the finite element simulation results.