Mechanical Properties And Microstructure Evolution Of Ultra-fine Grained 1060 Aluminum Alloys Prepared By Composite Upsetting Extrusion

1060 aluminum alloy has the characteristics of small density,good electrical and thermal conductivity,excellent machining performance and molding performance,but due to poor mechanical properties,especially the hardness and strength is too low to limit the wide range of applications.This paper designs a new technology of cyclic equal channel compression(CECC),the Equal Channel Angular Pressing(ECAP)and Muti-axial Compression(MAC)are combined for CECC,namely 4 ECAP+2 MAC technology,including four different routes that are CECC of route A,CECC of route B_A,CECC of route C,CECC of route B_C,and set up four control experiments that are simple ECAP of route A,simple ECAP of route B_A,simple ECAP of route C,simple ECAP of route B_C,the purpose is to improve mechanical properties of 1060 aluminum alloy by CECC.DEFORM 3D finite element simulation software was used simulate the change of damage,stress-max principle,stress-effective,strain-effective during CECC by route B_C,researched the change of microhardness and tensile property after CECC by different 8 routes of1060 aluminum alloy,the morphology of tensile fracture was observed by scanning electron microscope,and researched the grain size variation,orientation transformation,phase change during 1060 aluminum alloy CECC process by EBSD.The main contents and results as follows:(1)Through research the mechanical properties after four different routes of CECC and four different routes of simple ECAP:after four different routes of CECC,the microhardness and tensile strength are greater than any routes of simple ECAP,the except the percentage elongation is lower after simple ECAP of route A,the percentage elongation of specimen is over 10%after other seven routes deformed,good percentage elongation is maintained.So CECC technology overall batter than simple ECAP technology;(2)Compare the mechanical properties after four different routes of CECC:After route B_Cof CECC have highest microhardness(152.46HV)and tensile strength 453.8MPa),also has better percentage elongation(13.6%)and plasticity,after route B_C of CECC has the best mechanical properties of 1060 aluminum alloy;(3)Through research the change of grain size after route B_C of CECC of 1060 aluminum alloy:With the increase of deformation pass,grain size was gradually refined.After sixth MAC deformation,the proportion of grain size less than 1μm accounted 86.51%,grain size became fine and uniform,and excellent ultrafine grain structure was obtained;(4)Through research the orientation transformation after route B_C of CECC of 1060aluminum alloy:Grain transformed in<001>,<101>and<111>between three directions on RD,TD and ND,in process of orientation transformation,grain can form two directions in the middle of orientation,at the same time,in ECAP process of CECC,grain appeared more obvious preference for a certain orientation in the direction of preferred orientation and more shear zone,as for MAC process,the preferred orientation disappear,and the shear zone is basically eliminated,after six pass of MAC deformation,grain preferred orientation is basic disappeared,grain is uniform in<001>,<101>and<111>on RD,TD and ND,and the shear zone was basically eliminated;(5)Through research the phase change after route B_C of CECC of 1060 aluminum alloy:The phase change is mainly morphological changes,and the overall trend is that large grains with large length-diameter ratio gradually change into mixed grains with different sizes,and then into small grains with small length-diameter ratio,the grain refinement is very obvious.