Research On Fatigue Behavior And Cyclic Plastic Constitutive Model Of Nickel-based Intermetallic Material

As one of the Ni₃Al-based intermetallic compounds,IC10 alloy has been gradually applied to aircraft engine.High temperature fatigue is one of the main failure modes of high temperature components,and the fatigue behavior of materials is closely related to the constitutive relationship.Therefore,based on the study of uniaxial tension of IC10 alloy,the research on high temperature low cycle fatigue mechanical behavior and cyclic plastic constitutive model are carried out.The main research work and conclusions are as follows:1.The uniaxial tensile test results of different strain rates of IC10 alloy at 600°C were obtained.The effects of different strain rates on the mechanical behavior and the variation of yield stress with strain rate under different residual plastic strains are obtained.The analysis results show that the uniaxial tension curves of the three strain rates are similar,the elastic are basically coincident,and both contain only the strain hardening stage;The yield stress of IC10 alloy is not sensitive to the change of variability at 600°C;2.The high temperature low cycle fatigue test of 0.65%,0.75%,0.85%and 1.0%strain stress levels was carried out on IC10 alloy under 600°C.The cyclic stress-strain curve,cyclic stress response curve and fatigue life were obtained.The analysis results show that the fatigue life decreases with the increase of strain level;When the strain level is higher than 0.65%,the material has obvious cyclic hysteresis characteristics and initial cycle hardening;The cyclic hysteresis loop is basically symmetrical about the origin,and the stress and strain maintain a good monotonic change;The cyclic stress response of the four strain levels are basically the same,showing that the initial cyclic hardening,followed by cyclic stability,and finally fracture;3.Based on the B-P theory,a cyclic plastic constitutive model is established by introducing an anisotropic fourth-order tensor.Based on the finite element method and ABAQUS software,the fatigue mechanical behavior of IC10 alloy under different load conditions was simulated and analyzed.The analysis results show that the uniaxial tensile calculation curve coincides well with the experimental curve in the elastic stage.,and maintain good consistency in the yield stage and the large plastic deformation stage;The calculated cyclic fatigue curves at different strain levels are in good agreement with the experimental curves at elastic loading,unloading,yield and cyclic vertices,which verifies the feasibility of anisotropic B-P constitutive model and the effectiveness of numerical simulation technology;4.Based on the theory of crystal plasticity,a mesoscopic cyclic plasticity constitutive model is established for the unit cell model.The high temperature fatigue mechanical behavior of IC10 alloy at600°C was simulated and analyzed by ABAQUS software.The analysis results show that the uniaxial tension calculation curve and the test curve are basically coincident,and the cyclic fatigue calculation curves and test curves at different strain levels have good consistency,indicating that the mesoscopic cyclic plastic constitutive model can well describe the high temperature fatigue inelastic response mechanical behavior of IC10 alloy.