超高强7055铝合金铸锭均匀化工艺优化

采用光学显微镜、扫描电镜、差热分析及透射电镜等手段,对一种航空用超高强7055铝合金大尺寸铸锭的均匀化工艺进行分析与优化。提出分级提高均匀化温度的方法,在确保不发生过烧的情况下,最大限度改善铸锭质量。结果显示:低温预均匀化时,铸锭中析出大量的Al₃Zr相,能够大幅度降低对后续挤压变形的再结晶比例;对铸锭采用400 ℃×4 h+465 ℃×16 h+474 ℃×8 h的分级均匀化处理工艺,能够显著消除铸锭中低熔点相的含量,提高铸锭质量,同时相比于原工艺节省约13 h。新的均匀化处理工艺,不仅提高了生产效率,还能够为后续工艺提供良好的铸锭。

Optimization of homogenization process of ultra-high strength 7055 aluminum alloy ingots

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.