Finite Element Analysis And Experiment Researches Of Aluminum Bronze Alloy Produced By Equal Channel Angular Extrusion

As a kind of excellent engineering materials, aluminum bronze alloy is widely used due to its outstanding physical, mechanical, wear-resistance and anti-corrosion properties. It is mainly used to manufacture high-strength, high elasticity, high wears resistance and high corrosion resistance parts. In order to further improve its comprehensive properties, most studies focused on changing the composition and volume of microelements in the alloys. However, this method has its own limitation and cannot suit higher standard and higher level. Therefore, there is an urgent necessity to develop a new technology to overcome this problem.Equal Channel Angular Extrusion (ECAE) technique is one of the methods of severe plastic deformation, which is used to prepare bulk ultrafine-grained materials by simple shear without changing its external size. Based on the study of the ECAE experiments of the aluminum bronze alloy, this paper applied finite element analysis to the whole ECAE process as well as the experimental investigation. Through the theoretical and experimental analysis, some significant original results have been obtained.Firstly, three-dimensional model of ECAE dies were assembled using UG software.Under the optimal settings of the model,element,mesh,boundary conditions, friction, optimizer, incremental, etc. Non-linear finite element software Deform-3D was utilized to simulate the process of aluminum bronze alloy undergoing one pass ECAE, and analyze distribution of deformation process, equivalent effective stain, and equivalent effective stress to the ECAE results. And the results indicated that curve of extrusion force versus time was divided into three stages: rapid increased stage, steady stage, slow increased stage in one pass ECAE process. Steady stage was main deformation stage; Equivalent effective stain, equivalent effective stain rate ,equivalent effective stress were different at different parts of the sample, at the shear deformation area , each of them reach the max at the corner area and inner is larger than external shows inhomogeneous overall .Secondly, analysis the ECAE results under the effect of different die parameters ,and the study shows that for the die with the inner angle is 90o, the extrusion force and the equivalent effective stain decreases gradually with the increase of the outer angle ; for the die with the outer angle of 32.4o, the extrusion force and the equivalent effective stain decreases gradually with the increase of the inner angle and the effect of the inner angle to the extrusion force is more significantly than the outer angle to the extrusion force; the extrusion force and the equivalent effective stress increase while the max equivalent effective strain decrease with the increase of the frictional factor; the extrusion force increase and the equivalent effective strain of the sample shows inhomogeneous with the increase of ECAE speed.Thirdly, the effects of preheating temperature,extrusion numbers,friction and annealing treatment on the microstructure and the mechanical properties of aluminum bronze alloy were analyzed and process variables were determined. The microstructure refinement and the reason of the improvement of the mechanical properties produced by high temperature ECAE processing were also discussed. The results shows that the preheating temperature should be higher than the eutectoid transformation temperature ; Grain size of the aluminum bronze alloy decreased while the hardness,yield strength,plasticity of the aluminum bronze alloy increase with the increase of the pass number; lubricate is an effective way to prevent inhomogeneous deformation of the sample and can enhance the microstructure refinement of the alloy; alloy recovery occurred when the annealing treatment temperature at 400℃and the hardness, yield strength, plasticity decreased. Recrystallization occurred and the hardness,yield strength,plasticity of the alloy increased at the annealing treatment temperature 500℃; When the annealing treatment temperature reached 600℃,the hardness,yield strength,plasticity of the alloy decreased due to the grow of the grain .The alloy has the best mechanical properties when the annealing treatment temperature at 500℃.Through the computer aided simulation and analysis, this paper studied the deformation process of ECAE and the optimum process parameters were determined; the influence of ECAE on the microstructure and mechanical properties of the aluminum bronze alloy were also investigated and the result shows that ECAE can efficiently refine the microstructure of aluminum bronze alloy and improve its mechanical properties; this study provide a new approach to the research of aluminum bronze alloy and has improved its applications. In addition, this study makes a significant contribution to the enrichment and development of ECAE theory.