High-temperature fatigue life prediction model of GH4169 electron beam welding joint
In order to establish the high-temperature fatigue life prediction model of GH4169 electron beam welded joints,fatigue tests at different temperatures were carried out to obtain the stress-life(S-N)curves respectively.The influence of temperature on the fatigue performance of joints was analyzed.The fatigue damage mechanism was studied by metallographic analysis and scanning electron microscope(SEM)test.The results showed that the effect of temperature on the fatigue performance of the joint was related to the load level.Under the load above 980 MPa,the fatigue performance showed an obviously downward trend with the increase of temperature.In addition,the fracture mechanism of joints presented transgranular brittle fracture at room temperature and cleavage fracture at high-temperature.On the basis of the above analysis,considering the changes of yield strength and grain size with temperature,the parameters in Basquin model were modified in combination with fatigue test data,and the high-temperature fatigue life prediction model of welded joints was established.The results showed that the prediction accuracy of the modified model was high when the yield strength and grain size were considered comprehensively,while the accuracy of the model was within±2 times of the dispersion band.
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万方数据
