Effect of Shot Peening on Surface State and Fatigue Performance of GH4096 Alloy
The shot peening experiment was conducted on S110 cast steel shot and Z300 ceramic shot,the morphology of shot peening surface was observed by SEM and three-dimensional contour instrument.The residual stress of shot peening surface was tested by X-ray diffraction,and the microstructure of cross section of shot peening layer was analyzed by OM and EBSD.The result shows that with the increase in shot peening intensity,the roughness of shot peening surface is increased.The roughness of ceramic shot peening surface is lower than that of cast steel shot.Residual compressive stress on the cast steel shot peening surface is between-860 MPa to-1000 MPa and with the increase in shot peening intensity,the residual compressive stress is slightly reduced.Residual compressive stress on the shot peening surface ceramic is between-1000 MPa to-1100 MPa,and with the increase in shot peening intensity,the residual compressive stress is slightly increased.After shot peening,projectile pits are formed on GH4096 alloy surface,plastic deformation occurs,grain boundaries are curved,and lattice deformation occurs,which causes a lot of dislocation set and low angle grain boundaries,and the grain orientation changes.The low-cycle fatigue life of GH4096 alloy at 650 ℃ can be improved by shot peening.The improvement effect of double shot peening on fatigue life is the most obvious,and strengthening effect of ceramic shot peening is better than that of cast steel shot peening.The strengthening effect of shot peening is mutually influenced by residual stress,surface roughness,and depth of strengthening layer.
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