Effects Of Homogenization Annealing On Microstructures And Properties Of 2026 Aluminum Alloy

In order to adapt to the large aircraft material higher strength and damage tolerance requirements,Alcoa in 2001 based on 2024 alloy by content to control the impurity elements Fe,Si and trace Zr,developed a new generation of high strength,high damage tolerance of 2026 alloy.This paper mainly studied the effect of different homogenization annealing processes structure and property of 2026 aluminum alloy in the casting,extrusion,solid solution and aging state.The researches mainly include two parts:(1)the effect of homogenization annealing on the microstructure and properties on the ingot and extrusion bar of 2026 aluminum alloy;(2)the effect of homogenization annealing on Microstructure and properties of 2026 aluminum alloy extrusion bar after solid solution and aging process.The main results are as follows:(1)During the homogenization process,the Al2Cu phases distribute along the grain boundaries and secondary dendritic arms dissolved and disappear,and the Al2CuMg phases along the grain boundaries and secondary dendritic arms break off and coarsen.The residual phases area percentage on the ingot reduces from 12.8%to a range from 3.2%to 4.1%after homogenized at different condition.It is seem that the heating and cooling rate during homogenization has little effect on the residual phase area percentage of the ingot.(2)The heating rate during homogenization process can affect the diffusing of Cu inner the grains of 2026 aluminum alloy ingot.During heating rate is 36?/h,the Cu element distribution in the grain is inhomogeneous,and which in turn result in the formation of different region with different contrast.During heating rate is 30?/h,the Cu element distribution in the grain is more uniform,and which in turn result in region with different contrast decrease.(3)After extrusion,the residual phases are broken and disturbed along the extrusion direction.The homogenization condition played some effect on the size of the broken residual phase.The average size and biggest size of residual phase in the extrusion bar without homogenization are 4.26?m and 6.46?m respectively.While average size and the biggest size of residual phase in the extrusion bar with different homogenization processes are in the range of 4.29?m to 4.78?m and 7.16?m to 9.82?m respectively.(4)During solid solution at 500? from 0.5hour to 4hours,the residual phase area percentage of the different extrusion bay reduces with prolong the time.After solid solution at 500? for 4 hours,the residual phase area percentage in the extrusion bar without homogenization is 0.8%,the residual phase area percentage in the extrusion bar with different homogenization processes is in the range of 1.0%to 1.2%.(5)During solid solution at 500? from 0.5hour to 4hours,the thickness of coarse grain ring in the different extrusion bars increases with prolong the time.It is seem that the homogenization processes can play some effect on the thickness of coarse grain ring.(6)It is seem that the different homogenization processes almost have no effect on the tensile property of the extrusion bar in T4 state(solid solution at 500? for 1 hour followed with natural aging for 40days).The yield strength of the different extrusion bars are in the range of 393MPa to 398MPa,the tensile strength of the different extrusion bars are in the range of 563MPa to 574MPa,the elongation rate of the different extrusion bars are in the range of 16.9%to 19.4%.The different homogenization processes almost have no effect on the tensile property of the extrusion bar in T6 state(solid solution at 500? for 1 hour followed with natural aging for 40days).The yield strength of the different extrusion bars are in the range of 312MPa to 334MPa,the tensile strength of the different extrusion bars are in the range of 402MPa to 425MPa,the elongation rate of the different extrusion bars are in the range of 10.8%to 14.8%.