Finite Element Simulation Of Ecap And Research Of Ecap Of Mg-Zn-Mn Alloy

Equal channel angular-pressing (ECAP) is currently the most promising fine-grained and ultrafine-grained materials processing means to significantly refine the grain and improved mechanical property by pure shear deformation mode, improved mechanical properties.The extrusion process under different coefficient of friction conditions of the ECAP model were simulated by finite element simulation software called Deform-3D. Analysis of the flow line of the deformation materials, the change of the extrusion load, the stress and the strain distribution of the ECAP model at channel parameters φ=90°, Ψ=20°. The simulation results show: the plastic deformation of the ECAP is pure plastic deformation. The load of ECAP is reduced by the billets pull out of the exit channel, and the maximum load that increases with the increase of the friction coefficient. The stress distribution of ECAP is complex, and the use of a lubricant is help to reduce the different metal flow in billets’inner and outer layers, that help to reduce the tendency to crack. ECAP show a gradient distribution of equivalent strain, and in the case of a high coefficient of friction, and its hard to maintain the uniform distribution of the effective strain.Extrusion the Mg-Zn-Mn alloy by the ECAP, and study the effect of the pressing passes and the temperature of extrusion at pass route BA, main in the microscopic properties, Microhardness and the corrosion resistance in PBS simulated body fluid at37℃. The result show that:ECAP at210℃can effectively reine microstructure of Mg-Zn-Mn alloy and increase its microhardness. After4passes ECAP pressing, the average grain size decreased from25μm to5.1μm, non-uniform grain size form a bimodal distribution. Microhardness increased from43.7HV to78.9HV. and the corrosion resistance in PBS simulated body fluid at37℃is decline with the pressing passes increase.The ECAP at variable temperature220℃-200℃-180℃-170℃is more effective refine the grain and make more uniform grain distribution. The average grain size decreased from25μm to2.1μm, the maximum grain size less than5μm. Microhardness from43.7HV increased to80.3HV. And the corrosion resistance in PBS simulated body fluid at37℃is decline with the pressing passes increase. Annealing process has a very significant impact on the microstructure of the4passes pressing Mg-Zn-Mn alloys. When the annealing temperature is160℃~180℃, the grain begins to grow, and higher than180℃, grain growth is serious, and micro-hardness decreased significantly. The4passes pressing Mg-Zn-Mn alloys have more excellent corrosion resistance by annealing treatment. The case of180℃has the best corrosion resistance in PBS simulated body fluid at37℃。...