时效制度对工业规格喷射成形7055铝合金组织和性能的影响

采用全自动控制往复喷射成形工艺制备大规格7055铝合金锭坯。锭坯经热挤压和双级固溶处理后,在不同时效工艺条件下进行双时效处理,测定时效态合金的抗拉强度(σb)、屈服强度(σ0.2)、伸长率(δ)、硬度(HRB)和电导率(γ),并观察其微观组织,研究时效制度对合金组织和性能的影响,并与120℃/24 h单级时效的合金样品进行性能对比。结果表明,锭坯经120℃/24 h时效处理后获得最高强度,抗拉强度(σb)高达725 MPa,屈服强度(σ0.2)为685 MPa,伸长率(δ)10.0%,硬度为96 HRB,电导率为30%IACS;双级时效后获得较好的塑性和抗应力腐蚀能力,但强度较低,且随着二级时效温度升高和时效时间延长,合金强度下降,伸长率增加,电导率提高。通过对正交实验结果进行分析,确定最佳双级时效处理工艺为:120℃/8 h+170℃/8 h,其综合性能最佳,σb、σ0.2和δ分别达到659 MPa、630 MPa和11.7%,硬度和电导率分别为95 HRB和39%IACS。与单级时效处理相比,电导率提高30%,抗应力腐蚀性能显著改善。

Effect of aging treatment on microstructure and properties of industrial large-scale spray-forming 7055 aluminum alloy

The industrial scale 7055 alloy billets were prepared by fully automatic controlled reciprocating spray forming technology.The effects of hot-extruded,double-stage solution and different aging treatments on the microstructure and mechanical properties of spray-deposited aluminum alloy were studied.It is shown that the spray-deposited 7055 aluminum alloy has the highest strength after the single-stage aging(120 ℃/24 h).The tensile strength,yield strength,hardness of HRB,extensibility and the conductivity are 725 MPa,685 MPa,96,10.0% and 30% IACS,respectively.The results also show that the double stage aging leads to excellent plasticity and stress corrosion resistance,but the strength is low.With the aging temperature and aging time of the double aging increasing,the alloy strength decreases,the plasticity and conductivity increase.The optimum double-stage aging process through the analysis of orthogonal experiments is:120℃/8 h+170℃/8 h.The alloy has excellent comprehensive properties after the double-stage aging treatment.The tensile strength,yield strength,hardness,extensibility and conductivity are 659 MPa,630 MPa,95(HRB),11.7%and 39%IACS,respectively.Compared with the single-stage aging treatment,the conductivity increases by 30%,stress corrosion resistance improves significantly.