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<p>A novel GH4720Li superalloy ingot underwent multi-directional forging (MDF) to investigate the effects of cogging cumulative strain on microstructure and mechanical properties, focusing on the underlying strengthening mechanisms. Microstructural observations revealed that the alloy exhibited a fine-grained, homogeneous microstructure along the forging direction after MDF with ∑∆ε = 2.00. Tensile tests showed an increase in yield strength (YS) and elongation (EL), from 873&#xa0;MPa and 21.9% in the solid-solution state to 959&#xa0;MPa and 24.1%, respectively, after MDF with ∑∆ε = 0.66. This improvement was primarily due to insufficient cumulative strain and deformation inhomogeneity in the initial stages, characterized by a high fraction of deformed grains and a low fraction of fine dynamic recrystallization (DRX) grains. After MDF with ∑∆ε = 2.00, YS and EL reached 1088&#xa0;MPa and 28.6%, respectively. However, despite continued strength enhancement, the improvement after MDF with ∑∆ε = 2.00 was marginal, with EL decreasing compared to ∑∆ε = 1.33, likely due to the homogeneity of the microstructure and texture. A comprehensive analysis of the strengthening mechanisms revealed that solid solution and precipitation strengthening were the dominant contributors. Thus, by optimizing the microstructure through MDF, materials with balanced strength and plasticity can be achieved.</p>

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Microstructure and Mechanical Properties of a Novel GH4720Li Superalloy Ingot in Cogging via Multi-directional Forging

  • 期刊论文

  • 发表日期：

    2025年3月29日

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  • Jing Fangyu,
  • Zhang Junbo,
  • Yan Zehua

摘要

A novel GH4720Li superalloy ingot underwent multi-directional forging (MDF) to investigate the effects of cogging cumulative strain on microstructure and mechanical properties, focusing on the underlying strengthening mechanisms. Microstructural observations revealed that the alloy exhibited a fine-grained, homogeneous microstructure along the forging direction after MDF with ∑∆ε = 2.00. Tensile tests showed an increase in yield strength (YS) and elongation (EL), from 873 MPa and 21.9% in the solid-solution state to 959 MPa and 24.1%, respectively, after MDF with ∑∆ε = 0.66. This improvement was primarily due to insufficient cumulative strain and deformation inhomogeneity in the initial stages, characterized by a high fraction of deformed grains and a low fraction of fine dynamic recrystallization (DRX) grains. After MDF with ∑∆ε = 2.00, YS and EL reached 1088 MPa and 28.6%, respectively. However, despite continued strength enhancement, the improvement after MDF with ∑∆ε = 2.00 was marginal, with EL decreasing compared to ∑∆ε = 1.33, likely due to the homogeneity of the microstructure and texture. A comprehensive analysis of the strengthening mechanisms revealed that solid solution and precipitation strengthening were the dominant contributors. Thus, by optimizing the microstructure through MDF, materials with balanced strength and plasticity can be achieved.