Effect of aging process on microstructure and properties of spray formed 2195 Al-Li alloy friction stir welded joint

doi:10.13251/j.issn.0254-6051.2024.10.012

Abstract

Abstract: Friction stir welding was conducted on 2195-T8 Al-Li alloy with 8 mm thickness under different welding heat input, and the welded joint was subjected to post-welding heat treatment at 205 ℃ for different aging time (6, 12, 18, 24 h). The microstructure and properties of the welded joint were analyzed by means of OM, TEM, SEM and universal tensile testing machine. The results show that when the heat input of friction stir welding is 1250 J/cm, the comprehensive mechanical properties of the welded joint are excellent, and the microhardness distribution of the joint is U-shaped. After aging at 205 ℃, in weld nugget zone, T₁, θ′ and δ′ precipitates increase with the aging time prolonging, and T₁ phase is the main phase, and then the precipitates coarsen with the aging time extend. In heat affected zone, based on the original distribution of a small number of T₁ phases, T₁, θ′ and δ′ phases increase gradually, and then with the increase of aging time, the density of precipitated phase decreases, T₁ and θ′ phases grow and coarsen, and some θ′ phases transform into θ phases. The mechanical properties of the welded joint reach the peak after aging for 12 h, the tensile strength of the joint is 497 MPa, which is 88.6% of the strength of the base material. However, the plasticity of the joint decreases, the fracture mode is intergranular fracture, and the microhardness of the joint increases from the original average 126.8 HV0.05 to 168.0 HV0.05.

Key words: 2195 Al-Li alloy, artificial aging, friction stir welding, microstructure and properties

CLC Number:

TG457.14

Xu Guifang, Song Ruizhi , Zhang Jie. Effect of aging process on microstructure and properties of spray formed 2195 Al-Li alloy friction stir welded joint[J]. Heat Treatment of Metals, 2024, 49(10): 78-84.

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