Characterizationof Ni-Based FGH96 Supperalloy Surface-Modified by Ageing and Laser Shock Peening

FGH96 Ni-based super-alloy,an advanced material for aircraft engine,was surface modified by ageing and by laser shock peening.The influence of the surface modification on the microstructures,phase-structures,fatigue-life and residual stress of FGH96 alloy was investigated with X-ray diffraction(XRD) scanning electron microscopy(SEM) and conventional mechanical probes.The results show that the aging and laser shock peening all had a major impact.For instance,ageing for 96 h resulted in formation of γ-phased austenite and high density of carbides chains.The multitask of laser shock peening included significantly decreasing grain-size,breaking-up carbides chains,driving carbide-cluster into matrix,inhibiting propagation of dislocation defects and increasing compressive residual stress.Besides,the increased residual compressive stress,spreading into the matrix,considerably suppressed the fatigue-crack origins,reduced the growth-rate of fatigue-crack and increased the fatigue-life.