| High performance aluminum alloy will be widely used in various sectors of the national economy and national defense industry due to the excellent mechanical properties.Microstructure and properties control by plastic deformation and heat treatment is a key common technology to improve the properties of aluminum alloy.6013 type aluminum alloy has been widely used in aerospace,rail transportation and other fields due to a series of comprehensive performance,such as highest strength,excellent welding,formability and corrosion resistance,etc.A 6013 type aluminum alloy,which chemical composition is Al-1.36Mg-1.02Si-0.92Cu-0.55Mn-0.08Zn-0.13Fe-0.12Zr-0.03Sr(mass fraction,%),was investigated by means of a series of experimental and testing methods,including optical microscopy,scanning electron microscopy,transmission electron microscopy,electron backscatter diffraction analysis,X-ray diffraction and microhardness testing,mechanical properties testing,intergranular corrosion and exfoliation corrosion testing.The regulation and its mechanism of plastic deformation and heat treatment on microstructure and properties of the 6013 type aluminum alloy were studied.Detail research contents and main conclusions are listed as follows:(1)The microstructure and properties of 6013 type aluminum alloy after solution-large deformation room / cryogenic temperature rolling-aging process were investigated.The results show that the 6013 type aluminum alloy prepared by this process has ultra-high strength,excellent plasticity and excellent intergranular corrosion resistance.After 560 ?×2 h solution,70.8 % room temperature rolling and 171 ?×3 h aging,the ultimate strength is 482.21 MPa,the yield strength is 419.42 MPa,the elongation is 10.0 %,the maximum depth of intergranular corrosion is 103.34 ?m and the classification of exfoliation corrosion is EA+,respectively.After 560?×2 h solution,70.8 % cryogenic temperature rolling and 171 ?×6 h aging,the ultimate strength is 470.32 MPa,the yield strength is 412.37 MPa,the elongation is 13.5 %,the maximum depth of intergranular corrosion is 70.22 ?m and the classification of exfoliation corrosion is EA+,respectively.The high performance is related to the high dislocation density increased in the matrix by large deformation rolling,and the low degree of recrystallization after aging.(2)The microstructure and properties of 6013 type aluminum alloy after solution-(over aging)-compressive plastic deformation-resolution-aging process were investigated.The results show that the 6013 type aluminum alloy prepared by this process has moderate strength,excellent plasticity and excellent exfoliation corrosion resistance;resolution treatment after compressive plastic deformation can significantly improve the plasticity of the alloy in the case of maintaining strength;over aging treatment before compressive plastic deformation can not improve the properties of the alloy obviously.After 560?×2 h solution,15 %,30 % and 45% compressive plastic deformation,560?×2 h resolution and 191?×4 h aging,the ultimate strength are 374.26 MPa,379.13 MPa and 393.57 MPa,the yield strength are 329.12 MPa,330.74 MPa and 352.36 MPa,the elongation are 18.6 %,19.1 % and 17.4 %,respectively;the maximum depth of intergranular corrosion are 384.15 ?m?449.86 ?m and 404.47 ?m,the classification of exfoliation corrosion are PB,PB and PB,respectively.After 560?×2 h solution,400 ?×24 h over aging,15 %,30 % and 45% compressive plastic deformation,560?×2 h resolution and 191?×4 h aging,the ultimate strength are 373.91 MPa,364.56 MPa and 378.21 MPa,the yield strength are 328.63 MPa,308.06 MPa and 326.84 MPa,the elongation are 21.5 %,20.9 % and 21.9 %,respectively,the maximum depth of intergranular corrosion are 459.35 ?m?453.93 ?m and 489.84 ?m,the classification of exfoliation corrosion are PB,PB and PB,respectively.The improvement of plasticity is related to the large number of high angle grain boundaries,the high degree of recrystallization,random distribution of the grain orientation and the high uniformity of grain size.(3)The microstructure and properties of 6013 type aluminum alloy after solution-(over aging)-compressive plastic deformation-prerecovery-resolution-aging process were investigated.The results show that the 6013 type aluminum alloy prepared by this process has higher strength,excellent plasticity and good exfoliation corrosion resistance;over aging treatment before compressive plastic deformation can not improve the properties of the alloy obviously.After 560 ? ×2 h solution,45 % compressive plastic deformation,250?×3 h prerecovery,560?×2 h resolution and 191?×4 h aging,the ultimate strength,yield strength and elongation are 430.52 MPa,362.59 MPa and 17.8 %,the maximum depth of intergranular corrosion is 455.28 ?m,the classification of exfoliation corrosion is PC,respectively.After 560?×2 h solution,45 % compressive plastic deformation,400?×3 h prerecovery,560?×2 h resolution and 191?×4 h aging,the ultimate strength,yield strength and elongation are 423.13 MPa,334.57 MPa and 16.1 %,the maximum depth of intergranular corrosion is 445.12 ?m,the classification of exfoliation corrosion is PB,respectively.After 560?×2 h solution,45 % compressive plastic deformation,250?×3 h+300?×3 h+350?×3 h+400?×3 h prerecovery,560?×2 h resolution and 191?×4 h aging,the ultimate strength,yield strength and elongation are 403.43 MPa,327.39 MPa and 19.2 %,the maximum depth of intergranular corrosion is 401.08 ?m,the classification of exfoliation corrosion is PC,respectively.After 560?×2 h solution,400 ?×24 h over aging,45 % compressive plastic deformation,250?×3 h+300?×3 h+350?×3 h+400?×3 h prerecovery,560?×2 h resolution and 191?×4 h aging,the ultimate strength,yield strength and elongation are 411.24 MPa,333.86 MPa and 18.7 %,the maximum depth of intergranular corrosion is 392.28 ?m,the classification of exfoliation corrosion is PB,respectively.(4)The microstructure and properties of 6013 type aluminum alloy after solution-cyclic channel die compression-resolution-aging process were investigated.The results show that the 6013 type aluminum alloy prepared by this process has moderate strength,excellent plasticity and excellent exfoliation corrosion resistance;cyclic channel die compression is beneficial to refine the grain of alloy,increase the uniformity of recrystallized grain distribution,and reduce the anisotropy of alloy.After 560?×2 h solution,480? cyclic channel die compression for 3 passes and 12 passes,560 ?×2 h resolution and 191 ?×4 h aging,the ultimate strength are 300.52 MPa and 357.00 MPa,the elongation are 15.1 % and 14.6%,the maximum depth of intergranular corrosion are 408.05?m and 450.44?m,the classification of exfoliation corrosion are PB and PA,respectively.6013 type aluminum alloys with excellent mechanical properties and corrosion resistance were prepared by means of plastic deformation and heat treatment,the results provide experimental and theoretical basis for optimizing the preparation process and the industrial application of high performance 6000 series aluminum alloy.It is of great significance to further improve the comprehensive properties of 6000 series aluminum alloy,expand its application fields,and meet the application requirements of highperformance aluminum alloys in the aerospace,rail transportation and other national major engineering fields. |
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