Abstract: Homogenization process of a large size of ultra-high strength 7055 series aluminum alloy for aviation was analyzed and optimized by means of metallographic microscope, scanning electron microscope, differential scanning calorimeter and transmission electron microscope. The method of increasing the homogenization temperature in-step was proposed to improve the ingot quality to the max extent without over-burning. The results show that the recrystallization ratio of subsequent extrusion deformation will be greatly reduced by the precipitation of Al₃Zr phase during pre-homogenization at low temperature. The process of 400 ℃×4 h+465 ℃×16 h+474 ℃×8 h homogenization can significantly eliminate the content of low melting point eutectic phase in ingot and obtain a high quality ingot, meanwhile it can save process time by about 13 h compared with the original process. The new homogenization process not only improves the production efficiency, but also provides a better quality ingot for the subsequent process.

Key words: ultra-high strength 7055 aluminum alloy, homogenization process, Al₃Zr phase, low melting point phase