Mg含量对Al-Zn-Mg合金铸态及轧制态组织和性能的影响

doi:10.13251/j.issn.0254-6051.2023.06.040

摘要/Abstract

摘要： 为探究Mg含量对Al-Zn-Mg合金组织和性能的影响, 以及冷轧后的时效处理对加工硬化效果的影响, 通过直读光谱、扫描电镜、金相显微镜及拉伸试验机等对不同变形+热处理工艺下的Al-6.0Zn-xMg(x=2、3和4)合金铸态及轧制态组织及性能进行分析。结果表明, Mg含量对铸态合金组织形貌、晶粒大小及第二相类型影响不大, 非平衡共晶T-AlZnMg相占比随Mg含量的增加而增加, 当Mg含量为4%时, 共晶相占比减小主要与晶界附近MgZn₂弥散相数量增多有关。均质化后经热轧+固溶+冷轧变形热处理后, 高熔点Al₃Fe相破碎并沿轧制方向分布, 显微组织演变过程为, 铸态组织→纤维组织→完全再结晶→纤维组织。随着Mg含量的增加, Al-6.0Zn-xMg合金轧板强度逐渐增加, 但增幅逐渐减小。冷轧后的时效处理使加工硬化效果降低80~100 MPa, 而伸长率提高6%~8%。3种合金中, Al-6.0Zn-4Mg合金的综合性能最佳。

关键词: Al-6.0Zn-xMg合金, Mg含量, 显微组织, 力学性能

Abstract: Effect of Mg content on the microstructure and mechanical properties of Al-Zn-Mg alloy and the effect of aging treatment after cold rolling on the strain hardening were studied by analysis of the as-cast and as-rolled microstructure and mechanical properties of Al-6.0Zn-xMg (x=2, 3, 4) alloys undergone different deformation+heat treatments with XRF, SEM, OM and universal tensile testing machine. The results show that the Mg content has only little effect on the morphology, grain size and second phase type in as-cast state, where the amount of non-equilibrium eutectic phase T-AlZnMg increases with increasing Mg content. When the Mg content is 4%, the amount of eutectic phase decreases, which is related to the increase of MgZn₂ disperse phase near the grain boundaries. After homogenization treatment, hot rolling and cold rolling processing, the high melting point Al₃Fe phase is broken and distributed along the rolling direction. The microstructure transforms as following: as-cast microstructure→fiber microstructure→recrystallized microstructure→fiber microstructure. With the increase of Mg content, the strengths of the as-rolled Al-6.0Zn-xMg alloys increase, but the increments decrease. Aging treatment after cold rolling results in an 80-100 MPa decrease of the strength, and 6%-8% increase of the elongation. Among the three alloys, the Al-6.0Zn-4Mg alloy shows the best comprehensive properties.

Key words: Al-6.0Zn-xMg alloy, Mg content, microstructure, mechanical properties

中图分类号:

TG335.5⁺5

秦翔智, 赵佳蕾, 王凯歌, 李兵, 赵巍. Mg含量对Al-Zn-Mg合金铸态及轧制态组织和性能的影响[J]. 金属热处理, 2023, 48(6): 229-236.

Qin Xiangzhi, Zhao Jialei, Wang Kaige, Li Bing, Zhao Wei. Effect of Mg content on microstructure and properties of as-cast and as-rolled Al-Zn-Mg alloy[J]. Heat Treatment of Metals, 2023, 48(6): 229-236.

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