Study On The Effect Of Composite Extrusion On The Microstructure And Properties Of 6061 Aluminum Alloy

6061 Aluminum Alloy belongs to Al-Mg-Si alloy,it has been widely used in fields of automotive and aerospace fields due to its good formability,strong corrosion resistance,low density and so on,and is one of the most promising materials in the future.Severe plastic deformation technology has developed rapidly with the increasing demand of high strength as well as lightweight mental materials,especially the ECAP(equal channel angular pressing)and the CCDC(Cyclic channel die compression).Large plastic deformation can effectively improve the strength of materials by refining the grains.Because of the simple preparation procedure and the low cost,more and more scholars have conducted deep exploration and research of the large plastic deformation.In this essay,the ECAP and CCDC methods are combined with testing mechanical properties,X-ray diffraction,EBSD and SEM through different routes of CECC.The effect of CECC process of Al-6061 alloy is researched in this paper and the results turn out that:(1)Under the extrusion speed of 35mm/min,the tensile strength and microhardness of 6061 aluminium alloy reached the maximum value.The tensile strength increases sharply with the increase of the pass of the extrusion.(2)When the dependent variable of the pass of specimen was 60%,the tensile strength of 3 passes of muiti-axial compression reached to 293.410 MPa,and the synthetic mechanical properties are the best.(3)The best composite process of Al-6061 is CCDC+ECAP+CCDC.The tensile strength was 1.4 times of single ECAP and CCDC,and elongation increased.The grain size delines from 110?130pm of initial statement to 0.98?m and the grain intensify is the most obvious among all the routes.In macroscopic view,it appears that the tensile strength and elongation are both increasing.