Two-stage Homogenization Of 3104 Aluminum Alloy And Recrystallization Behavior

Aluminum alloy 3104 is widely used for manufacturing beverage can due to its high strength,strong corrosion resistance and good formability.The tendency of manufacturing thinner and lighter beverage can requires excellent deep-drawing performance of the sheet,which requires the second phase particles to be fine and uniformly distributed as well as cube texture to be strong in the alloy.Large size particles will lead to scoring during deep drawing,and the second phase particles also have strong influence on the recrystallization behavior of the sheet.In this paper,the effect of homogenization on the microstructure, recrystallization behavior and recrystallization texture of the hot rolled aluminum alloy 3104 was investigated by means of differential scanning calorimetry analysis,hardness and electricity conductivity measurement, optical microscopy,quantitative metallographic analysis,scanning electronic microscopy and transmission electronic microscopy.The main results are as following:1) The effect of homogenization temperature on the second phase particles and saturation content of Mn in the matrix was studied. The results show that,during single homogenization,high temperature homogenization heat treatment(≥550℃) favors the elimination of the coarse non-equilibrium constituents particles, but the amount of Mn in solid solution is still high.And it is easy to be over-burnt when the temperature is over 615℃.Low temperature homogenization heat treatment(≤500℃) favors the precipitation of Mn-rich precipitates,but the coarse constituents particles are still remained.The content of Mn dissolved in the matrix is the lowest when the homogenization temperature is up to 450℃.2) Two-step homogenization technique is proposed,which is aimed at dissolving of the coarse non-equilibrium constituents particles by high temperature homogenization heat treatment at the first step and precipitating the Mn-rich precipitates by low-temperature homogenization at the second step.In this thesis, the optimal homogenization heat treatment is 600℃/12h+450℃/12h.Through this two-step homogenization treatment the residual phase particles are uniformly distributed in the alloy,the average size of which is about 17.9μm~2,and the Mn-rich precipitates are sufficiently precipitated which leads to the high conductivity up to 41.5IACS%.3) The status of Mn atoms in aluminum alloy 3104 has a significant influence on the recrystallization temperature of the as-rolled sheet.The precipitation of Mn-rich precipitates is promoted and the recrystallization temperature decreases by adopting the two-step homogenization treatment compared with the single homogenization treatment.The recrystallization temperature of aluminum alloy 3104 is 465℃,442℃,400℃,323℃and 320℃, when it is homogenized at 450℃/12h,500℃/12h,550℃/12h, 600℃/12h,600℃/12h+450℃/12h,respectively.4) The volume fraction of the recrystallization texture component increases with the enhancing homogenization temperature,and the two-step homogenization can be of benefit to the formation of the cube texture component.The highest fraction of the recrystallization texture is obtained when the alloy is homogenized at 600℃/12h+450/12h,followed by hot rolling and annealling.