时效制度对喷射成形7055铝合金机轮轮毂锻件性能的影响

摘要

The large-sized 7055 aluminum alloy billets with diameter of 495 mm were prepared by fully automatic controlled reciprocating spray forming technology. The tensile strength, yield strength and conductivity of 7055 forging under different aging treatment, including T76 (120 ℃/6 h+160℃/8 h), T74 (120℃/6 h+160℃/18 h), T73(120℃/6 h+160℃/30 h), were detected. The effect of different aging treatment on mechanical properties and fracture mode were studied, which were compared with the data of forging under T6(120℃/24 h) heat treatment stage. The results show that, with increasing aging time (≤30 h), both the tensile strength and yield strength decrease, the yield ratio is slightly decreases simultaneously, and the fracture toughness increases. In contrast to the brittle fracture under T6 heat treatment state, the test bars show typical feature of the ductile fracture under T74 and T73 aging treatment state after tensile test. The fracture toughness and the electrical conductivity increase with increasing the aging time. The wheel hub forgings under T74 and T73 state can meet the application requirement of tire.%采用全自动控制往复喷射成形工艺制备直径为495 mm的大规格7055铝合金锭坯，经热挤压、2次锻压成形和双级固溶处理后，分别进行 T76(120℃/6 h+160℃/8 h)、T74(120℃/6 h+160℃/18 h)和 T73(120℃/6 h+160℃/30 h)双级时效处理，测定时效态锻件各取样部位的抗拉强度(σb)、屈服强度(σ0.2)和电导率(γ)，并与单级时效T6态(120℃/24 h)的锻件进行对比，研究时效制度对轮毂锻件各取样部位性能和断裂方式的影响。结果表明，随二级时效时间延长，锻件的抗拉强度与屈服强度均降低，屈强比也略有降低，但断裂韧性提高；在T74和T73时效状态下试棒拉断后为典型的韧性断裂；随二级时效时间延长，锻件的断裂韧性和电导率均呈升高趋势，并改变T6态下的脆性断裂特征，满足机轮的应用要求。