Influence of pre-aging on natural aging and bake hardening behavior of AlZnMgCu aluminum alloy

doi:10.13251/j.issn.0254-6051.2023.10.028

Abstract

Abstract: Natural aging behavior of the AlZnMgCu aluminum alloy was investigated, and the hardening effect of natural aging was reduced by pre-aging treatment, which improved the final hardening effect of artificial aging process. The microstructure was characterized by using OM and TEM, the microhardness and tensile properties were tested. The results indicate that pre-aging treatments improve the initial hardness of the AlZnMgCu alloy, but after natural aging for 12 d, the final hardness is actually lower than that of direct natural aging after solid solution, which is reduced by 24% (pre-aging at 120 ℃). After pre-aging treatment, the yield strength and tensile strength of the specimen increase by 165 MPa and 48 MPa and by 55.9% and 11.2%, respectively, after natural aging and 180 ℃×20 min artificial aging treatment. After solid solution plus natural aging treatment, the distribution of GP zone in the matrix is uneven, while after pre-aging treatment, the size and distribution of GP zone are relatively uniform and exhibits a coherent relationship with α-Al matrix. After pre-aging, natural aging, and artificial aging, η′ phase particles are uniform and dispersed, and exhibit a semi-coherent relationship with α-Al matrix, which plays a significant role in aging hardening.

Key words: AlZnMgCu aluminum alloy, pre-aging, natural aging, bake hardening

CLC Number:

TG156.2

Xu Xiangmei, Wang Qichen. Influence of pre-aging on natural aging and bake hardening behavior of AlZnMgCu aluminum alloy[J]. Heat Treatment of Metals, 2023, 48(10): 188-191.

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