7A99铝合金锻件双级时效组织性能

摘要

采用金相、扫描电镜、透射电镜分析及拉伸性能和断裂韧度试验等手段,研究了7A99铝合金锻件双级时效处理后的组织和性能.结果表明:7A99铝合金锻件经过120℃/4h+165℃/8 h双级时效处理后的抗拉强度、屈服强度、伸长率和电导率分别为548 MPa,513 MPa,12.0％和38.2％IACS;锻件的L-T向断裂韧度为30.5 MPa·m1/2,锻件显示了较好的强韧匹配和耐蚀性;合金的断裂方式为穿晶韧窝断裂方式;主要沉淀相为η′相和η相.%Effects of two-step aging treatment on the microstructure and mechanical properties of 7A99 forged aluminum alloy were studied using optical microscopy (OM),scanning electron microscopy (SEM),transmission electron microscopy (TEM),tensile test and fracture toughness test. The results show that after 120 ℃/4 h +165 ℃/8 h two-step aging treatment,the ultimate tensile strength,yield strength,elongation and electrical conductivity are 548 MPa,513 MPa,12. 0％ and 38. 2％ IACS,respectively. Meanwhile,the L-T toughness fracture is 30. 5 MPa·m1/2 . The fracture mode of the alloy is transgranular dimple fracture mechanism, and the major precipitates are η′and η phases under the aging condition.