Fracture cause of check rod

The check rod was broken during service. The reason for the fracture of the check rod was analyzed by means of macro observation, chemical composition analysis, mechanical property test, metallographic examination, scanning electron microscope and energy spectrum analysis. The results show that there was a original crack in the check rod, which was a weak link in the use process and was easy to cause stress concentration. Fatigue fracture of the check rod occurred after cyclic loading.