THERMAL FATIGUE AND FRACTURE MECHANICS ANALYSIS OF GREY CAST IRON

The in-phase and out-of-phase thermal fatigue,the C-P type and P-C type isothermal fa-tigue of grey cast iron were experimentally studied.The fatigue life was evaluated analyticallyby using the elastic-plastic fracture mechanics method(mainly J integral).The results of ex-periments and calculations showed that the lifes of in-phase and C-P type fatigue are longerthan that of out-of-phase and P-C type fatigue respectively within the same strain range.This is in contrast to the results of other materials such as low carbon steel.On the other hand,the predicted lifes are consistent with experimental results.This suggests that J integral as amechanics parameter for characterizing the thermal fatigue strength of grey cast iron and themechanics model and the calculation method developed here are efficient.A parameterΔWwas proposed from energy aspect to characterize the capacity of crack propagation.The isothermal fatigue life is the same as the thermal fatigue life for identical ΔWvalues.