分级均匀化处理对7A55合金组织与性能的影响

Influences of Multistage Homogenization Treatment on Microstructure and Mechanical Properties of Al-Zn-Mg-Cu Aluminum Alloy

研究了不同的均匀化热处理制度对7A55铝合金显微组织和性能的影响。利用OM和SEM观察了合金的微观组织,测试了其硬度与力学性能。试验结果表明,经不同的均匀化处理后,7A55铝合金的硬度、强度和伸长率均呈现增大的趋势。相较铸态合金,经三级均匀化处理后合金硬度(HV)提高了27%,抗拉强度提高了12.3%,伸长率提升了58.3%。均匀化处理可以显著改善铸态组织,包括晶界处的非平衡共晶相及晶内的粗大第二相。多级均匀化处理后的效果好于单级均匀化处理。特别是经三级均匀化处理后,晶界处的共晶相尺寸变得细小且不连续,晶内的粗大第二相完全固溶到晶内。

The effects of homogenization treatment on microstructure and properties of 7 A55 aluminum were investigated.The microstructure was sobserevd using OM and SEM.The hardness and mechanical properties of the alloy were tested.The results indicate that the hardness,strength and elongation of7 A55 aluminum alloy are increased after different homogenization treatment compared to the cast state.After three-stage treatment,the hardness,tensile strength and elongation of the alloy are increased about 27%,12.3% and 58.3%,respectively.The cast structure is improved after homogenization treatment,including non-equilibrium eutectic phase at grain boundaries and bulky second phase in grain.The multi-stage homogenization effect is superior to single homogenization treatment,especially three-step treatment.The eutectic phase at grain boundaries become fine and discontinuous,and the bulky second particles in grains are dissolved into the grain.