Microstructure evolution and residual stress changes of the GH4169 alloy by wet shot peening

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GH4169 alloy was shot-peened with processing durations of 3 min and 10 min. The effects of dry and wet shot peening on the microstructure and residual stress were investigated. The results demonstrated that a severely deformed layer manifests on the surface of the shot-peened GH4169 alloy samples. Compared with the dry-peening samples, the surface defects of wet-peening samples obviously decrease. With the shot peening treated for 10 min, the surface microhardness of the dry peening and the wet shot peening increased by 20% and 17% respectively compared with the original surface hardness. The deformation mechanisms of the GH4169 alloy could be attributed to dislocation and deformation twining, as detected by TEM observations. Compressive residual stress was introduced into the surface layer of the shot-peened GH4169 alloy. The maximum surface residual compressive stress (SRS) and maximum residual compressive stress (MRS) were -586 MPa and -795 MPa, respectively. The MRS and SRS were improved with increasing processing duration. The SRS of the wet-treated specimens was slightly higher than that of the dry-treated samples under the same processing parameters. However, the MRS of dry-treated samples was much larger than that of the wet-treated samples due to the higher shot intensity.