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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。
A large-size 7055 aluminum alloy ingot with a diameter of 495 mm was prepared by automatic reciprocating injection molding. After heat-pressing, 2-forging and two-stage solution treatment, ℃ / 8 h), T74 (120 ℃ / 6 h + 160 ℃ / 18 h) and T73 (120 ℃ / 6 h + 160 ℃ / 30 h) (Σb), yield strength (σ0.2) and electrical conductivity (γ) were compared with forgings in single-stage aging T6 state (120 ℃ / 24 h). The effects of aging system on the performance and fracture The impact of the way. The results show that the tensile strength and yield strength of the forgings decrease with the increase of the second-stage aging time, and the yield strength decreases slightly, but the fracture toughness increases. Tensile strength of the forgings is a typical ductile fracture under T74 and T73 aging conditions The fracture toughness and electrical conductivity of forgings all tended to increase with the second aging time, and changed the brittle fracture characteristics under T6 condition to meet the application requirements of the wheel.