| In recent years,wrought magnesium alloys have become increasingly widely used in aerospace,medical materials,and transportation.The magnesium alloy shear-extrusion process designed in this research is a deformation process that combines equal channel extrusion and traditional forward extrusion,which combines the advantages of the two extrusion processes,improving the structure,and has simple operation.Features such as precise size.This paper takes Mg-4Sn-2Zn-0.5Ca(x=0,2,4,6)magnesium alloy as the research object,and uses finite element simulation to simulate the shearextrusion deformation process under different shear angles and different shearextrusion ratios.The Mg-4Sn-2Zn-0.5Ca alloy after solution treatment was selected for shear-extrusion experiments,and the effects of Sn element content and shear-extrusion ratio on the microstructure and mechanical properties of the alloy after shear-extrusion were studied.The DEFORM-3D software is used to study the influence of die structure on the shear-extrusion deformation process.In this paper,different die structures are designed through different shear angles,and from the aspects of extrusion load,metal flow rate,equivalent temperature,equivalent strain,etc.The simulation results are analyzed and compared,and the best shear angle is 90°.On this basis,the influence of the shear-extrusion ratio on the shear-extrusion forming process was studied,and the fluidity and uniformity of the alloy were evaluated by means of point tracking.Mg-x Sn-2Zn-0.5Ca alloys with different Sn content were subjected to shearextrusion deformation,and the changes in microstructure and mechanical properties of Mg-x Sn-2Zn-0.5Ca alloys with different Sn content were studied..When the Sn content is 4 wt.%,the alloy has the largest number of dynamic recrystallized grains and the most uniform structure.At this time,the mechanical properties of the alloy are the best.After shear-extrusion,the fracture of Mg-x Sn-2Zn-0.5Ca alloy is mainly quasi-cleavage ductile fracture.After adding Sn element,the cleavage surface at the fracture decreases and the dimples increase,but the brittle phase Mg2 Sn in the alloy after excessive Sn addition The increase in phases reduces the strength of the alloy.The high temperature tensile test of Mg-4Sn-2Zn-0.5Ca magnesium alloy by solution treatment and shear-extrusion,the increase of temperature makes the elongation of the alloy significantly increase,but the strength will decrease.After shear-extrusion deformation,the hot tensile properties of Mg-4Sn-2Zn-0.5Ca magnesium alloy are significantly improved,and the elongation improvement effect is very obvious,and the elongation of the alloy after stretching exceeds 100%.After high temperature stretching,the fractures are ductile fractures.The higher the temperature,the size and number of dimples will increase,and the depth of dimples will also increase,reducing the strength of the alloy and increasing the toughness.The microstructure and mechanical properties of Mg-4Sn-2Zn-0.5Ca magnesium alloy when the shear extrusion ratio is 4,6,and 10.When the shear extrusion ratio increases,the degree of recrystallization of the alloy continues to increase,the crystal grains become smaller,and the structure is more uniform.At the same time,the microhardness,tensile strength and yield strength of the alloy continue to rise,but the elongation decreases slightly.The fractures of alloys with different shear-extrusion ratios are all quasi-cleavage ductile fractures.After the shear-extrusion ratio increases,the fracture dimples increase significantly,and the dimple size decreases and the depth becomes shallower.After peak aging,the tensile strength and yield strength of the shear-extrusion Mg-4Sn-2Zn-0.5Ca alloy have been significantly improved,but the elongation has decreased. |
PDF Full Text Request