Study On Microstructure And Properties Of 6101 Aluminum Alloy Processed By A Continuous Expansion Extrusion Approach

Al-Mg-Si alloys are characterized by high strength to density ration,good conductivity,formability and corrosion properties to be the best candidates for conducting structural materials.One of the key challenges for the application of AlMg-Si alloy conductor is the trade-off between strength and electrical conductivity.An intrinsic drawback of the conventional methods used to strengthen metallic materials,including alloying,strain hardening and deformation will lead to a significantly loss in conductivity.This paper aimed at deal with the trade-off between strength and electrical conductivity by addressing a novel expansion continuous extrusion process combined with artificial aging.During the process,an as-cast rods with a diameter of 20 mm were processed to width(a)×thickness(b)=80×5 mm sheet.And subsequent heat treatment process was used to synergistically enhance the strength and conductivity of the alloy.Through this combined process,an Al-Mg-Si alloy conductor profile with high strength and conductivity was produced.Physical simulation,finite element simulation,microstructure characterization and mechanical and electrical conductivity tests were conducted to investigate what the differences that heat treatments would make on microstructure,mechanical properties and conductivity of 6101 aluminum alloy processed by continuous expansion extrusion.The main conclusions are as follows:(1)The true stress-strain curve of 6101 aluminum alloy showed the characteristics of dynamic softening.Through the calculation of constitutive equation,the deformation activation energy Q of 6101 aluminum alloy was 236.5545 k J/mol.(2)The continuous casting rod had coarse grains and the size was about 331 μm.The grain orientation angle presents a "bimodal" distribution;After hot compression tests at 300 ℃,400 ℃ and 500 ℃,the dendrite structure disappeared and the grain size decreased significantly.After hot compression at 25 ℃,100 ℃ and 200 ℃,the dendrite structure still existed and the temperature had a positive effect on the retention of dendrite structure,while the strain rate had a negative effect on the retention of dendrite structure.(3)The temperature field of continuous expansion extrusion changed from 20 ℃-480 ℃,the billet did not need preheating,there was severe shear deformation zone(IISB),and the cumulative equivalent effect became about 9.(4)After continuous expansion extrusion,the strength and conductivity of 6101 plate were improved simultaneously.There were many samples with excellent comprehensive properties after heat treatment.Generally,190 ℃ aging had better comprehensive properties,and pre-deformation promoted the improvement of comprehensive properties.Dislocation plays an important role in diffusion.Increasing aging temperature and pre-deformation would promote and accelerate the β"→β’ phase transition.