Study On Fracture Basic Problem Of23MnNiMoCr54by Electron Theory

Based on the empirical electron theory in solid and molecule (EET), the statistical values of the phase structure factors and the interface conjunction factors of different microstructures of the round link chain for mining made of23MnNiMoCr54steel were calculated. Finally, tensile strenghth, elongation and impact energy after medium temperature tempering were calculated in theory, and the relative differences the calculating results and experimental results are less than10%. Based on the theoretical calculating of the mechanical properties of different microstructures, the relations of fatigue behaviour of different microstructures under cyclic loading with the electron structures were analysed. The results show that:the maximal value (△ρmax),the minimum value (△ρmin) correspond to the characteristic strength σmax*and σmin*of the interface respectively; the number of atom state (σ) corresponds to the stability of the interface; compared with low temperature tempering and high temperature tempering, σmin*of medium tempered structure of23MnNiMoCr54steel is so larger that it can stop the crack initiation and prolong the incubation period (No) of the crack initiation; σmax*is so larger, stopping the crack breaking the interface, that the threshold of fatigue crack propagation (△Kth) is larger; the number of atom state (σ) is larger, the stability of the interface will not be broken easily by cyctic loading, therefore the interface is more stable and the cycle time (N) is more larger. N0,△Kth and N of the medium tempered structures all appear the peak values, so the fatigue properties after medium temperature tempering are the best. It is in accordance with reality.