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通过OM、SEM、TEM观察以及EBSD和力学性能测试等手段研究了不同热加工工艺对Al-Mg-Si-Cu-Zn合金板材组织、织构和成形性能,以及固溶淬火后等温时效对其析出行为的影响规律。结果表明,2种热加工工艺对T4P预时效态合金的强度和应变硬化指数n基本无影响,但是对平均塑性应变比rˉ、Δr以及不同方向延伸率影响显著;不同热加工过程对合金组织和织构演化均有影响,成形性能较好的固溶淬火态合金板材平均晶粒尺寸略大且呈双模型晶粒尺寸分布特征,其织构组分较多,但是强度较低。对该淬火态合金进行185℃人工时效20 min,其硬度即可升高65 HV,进一步时效到5 h达到峰值硬度132 HV,对应的拉伸性能可达Rp=318 MPa,Rm=364 MPa,A=13%,拉伸断口为典型的塑性断裂。该合金在185℃时效时仍以Mg-Si相析出为主,如b“、b’和Q’相等,峰时效后b”相主要沿b轴方向生长,最后转化为b’和Q’相,合金表现出较好的时效稳定性。
The microstructure, texture and formability of Al-Mg-Si-Cu-Zn alloy sheets by isothermal heat treatment were investigated by OM, SEM, TEM observation, EBSD and mechanical properties test. Precipitation behavior of the law. The results show that the two kinds of hot working process have little effect on the strength and the strain hardening index n of T4P pre-aged alloy, but have significant influence on the average plastic strain ratio r ˉ, Δr and the elongation in different directions. Different hot- The average grain size of solid solution-quenched alloy sheet with good formability is slightly larger and shows the bimodal grain size distribution. The texture components are more, but the strength is lower. The hardness of the quenched alloy at 185 ℃ artificial aging for 20 min, the hardness can be increased 65 HV, and further to 5 h peak hardness of 132 HV, the corresponding tensile properties of up to Rp = 318 MPa, Rm = 364 MPa, A = 13%, tensile fracture is a typical plastic fracture. When aging at 185 ℃, the Mg-Si phase is still dominated by the precipitation of the Mg-Si phase. For example, b ’’, b ’and Q’ are equal and the b ’phase mainly grows along the b axis after peak aging and finally becomes b’ and Q ’Phase, the alloy showed good aging stability.