Effect of grain size on 650 ℃ tensile properties of GH4720Li nickel-based alloy

doi:10.13251/j.issn.0254-6051.2025.01.031

Abstract

Abstract: GH4720Li alloy bars were solid solution treated at different temperatures of 1100, 1090, 1080, and 1070 ℃ to obtain four different microstructure with average grain sizes of 24, 18, 15 and 3-5 μm, respectively. The effect of grain size on the high-temperature tensile properties of the alloy at 650 ℃ was investigated. The results show that with the reduction of grain size, the 650 ℃ strength of the GH4720Li alloy increases, accompanied by a decrease in plasticity. When the grain size is further reduced to 3-5 μm, the plasticity begins to increase, and at this time, the alloy exhibits the optimal comprehensive tensile properties at 650 ℃. This is attributed to the pinning effect of primary γ′ strengthening relative to grain boundary, resulting in a fine grain structure that not only provides a large number of grain boundaries and improves strength, but also disperses plastic deformation, reduces stress concentration, and improves plasticity. Simultaneously, an appropriate amount of secondary and tertiary γ′ strengthen phase can further ensure the strength of the alloy.

Key words: GH4720Li nickel-based alloy, microstructure, grain size, high temperature tensile properties

CLC Number:

TG132.3⁺2

Guo Jing, Wen Xiaocan, Wang Qiang, He Xin, Lü Shaomin, Xie Xingfei, Qu Jinglong, Du Jinhui. Effect of grain size on 650 ℃ tensile properties of GH4720Li nickel-based alloy[J]. Heat Treatment of Metals, 2025, 50(1): 201-205.

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