The purpose of homogenization annealing is to deal with the non-equilibrium Fe phase and Mn phase in aluminum alloy. During the homogenization annealing process, the non-equilibrium (AIFeSi) phase and eAl6, FeAlm. The phases gradually dissolve and transform to the equilibrium (AIFeSi) phase and FeAl3 phase respectively. At the same time, the original (AIFeSi) phase and FeAl3 phase continue to grow. The MnAl6 phase in the eutectic is prone to transition from non-equilibrium crystallization to equilibrium state during the high-temperature and long-term homogenization process, and gradually dissolves into the matrix. And the nascent MnAl6.
Its shape is irregular block or flake, and its sharp corners can dissolve and spheroidize under certain conditions, which can reduce the risk of cracking during rolling. Improvement of homogenization annealing process:
0 Ensure that the homogenized annealing temperature of aluminum alloy cast and rolled coils is between 570C and 600C, with the best being 580%C. The holding time is generally controlled between 10h and 13h according to the coil size and furnace loading capacity;
2 Homogenization annealing of aluminum alloys containing more Fe and Mn elements has good results.
Generally, the cast-rolled coils are uniformly annealed directly, or after cold rolling. In addition, a metallographic microscope with photography is added to analyze the morphology, distribution and size of pinholes in each inspection, and a pinhole file for each batch of products is established, which is of great help in controlling pinholes.