Corrosion Behavior Of Two-stage Aging 7N01 Aluminum Alloy

7N01 aluminum alloy is widely used in aerospace,industrial construction,transportation and so on.Application potential of 7N01 aluminum is limited due to its high exfoliation corrosion sensitivity and stress corrosion sensitivity.two-stage aging process is simple and usually used to improve the corrosion resistance of 7N01 aluminum alloy in industry.GP form in pre-aging stage of the two-stage aging.? 'phase and ? phase precipitate in second stage of the two-stage aging.The size,distribution and the number of those phase will play significant impact on the performance of the alloy.Therefore,the performance of two-stage aging aluminum alloy is mainly determined by the final aging process.In this paper,the microstructure and corrosion behavior of 7N01 aluminum alloy were studied at 110 ?/4h as the initial aging process.The main results are as follows:(1)When temperatures of final aging are 140 ?,160 ?,180?,the alloy's peak hardnesses are 131HV?124HV and 113HV.When temperatures of final aging is 140 ?,finally the exfoliation corrosiondepth is basically stable at 230?m.When temperatures of final aging is 160 ?,the exfoliation corrosiondepth changed dramatically and is basically stable under 50?m.Taking hardness and anti-off corrosion resistance into consideration,final aging temperature of7N01 aluminum alloy is 160 ?.(2)Structure of alloy aging at 110 ?/4h is GP.When the final aging time is 2,8h and 16h,? '(MgZn2)phase is precipitated in the crystal,and a few precipitates,continuous precipitates and precipitates with Larger distance are formed in the grain boundary respectively.(3)In the exfoliationro corsion test,the corrosion in alloyaging at 110 ?/4h began with pitting and expanded at pitting.When the final aging time of alloyis 2h and 8h,the corrosion in the alloy began with intergranular pitting,expanded along grain boundary;when the final aging time of alloy is 16h,the corrosion began with intergranular pitting and approximate uniform corrosion expansion.(4)When the alloy is severely exfoliated,the alloy produces a intergranular corrosion which is wide in the middle and narrow in the ends,in which corrosion product produces a force in the grain boundary direction,leading to grain boundary cracking and corrosion expansion.(5)When the final aging time of alloy is 16h,the tensile strength of the alloy is 351.92 MPa and ?b(liquid)/?b(air)of the alloy is 0.9872.Corrosion cracks did not appear at fracture.The stress corrosion resistance less affected by anodic dissolution.The stress corrosion resistance of the alloy is the best.