Effect Of Pre-strain And Intermediate Annealing On The Recrystallization In Al-1.2Mn Alloy

Al-Mn alloy foil is widely used as current collector within lithium ion battery due to its high strength, strong corrosion resistance and good conductivity. For the reason that Al-Mn belongs to non-heat-treatable aluminium alloy, it is very important to optimize thermomechanical treatment before the foil cold rolling, which could control the grain structure Al-Mn foil. This paper systematically studies the effect of pre-strain and intermediate annealing on the recrystallization during final annealing in Al-Mn alloy. Furthermore, the influence of final annealing temperatures on the evolution of microstructure has also been investigated.(1) By means of designing and optimizing pre-strain and intermediate annealing treatment, the recrystallization annealing microstructure of final cold rolled Al-1.2Mn alloy was controlled, making the cold rolled microstructure transform in continuous recrystallization and achieving ultrafine grain microstructure with average grain size of ~2μm.(2) The transformation scheme of continuous recrystallization induced by pre-strain and intermediate annealing treatment was systematically analyzed. The evolution behaves in a continuous manner with no observable nucleation centers or any distinguishable transformation front, while deformation texture retained in dominated state and no conventional annealing texture appeared.(3) The influence of final annealing temperature and time on continuous recrystallization microstructure was investigated. Bimodal microstructure with ultrafine grains and coarse grains could be obtained at elevated annealing temperatures. The size of area of the ultrafine grains in the bimodal microstructure would decrease with annealing temperature and time and when the annealing temperature high enough and the annealing time long enough, the ultrafine grains would vanish, leaving a coarse grain microstructure.