Crankshaft crack cause

A cracked crankshaft was analyzed by means of macroscopic observation, chemical composition analysis, mechanical property test and microscopic analysis. The results show that the crankshaft had poor lubrication during service, which caused friction between the crankshaft and the copper alloy bearing bush. The phenomenon of dissimilar metal infiltration occured under the influence of high friction temperature, and many microcracks filled with copper alloy were formed on the surface of the crankshaft. These cracks became fatigue sources, which eventually led to fatigue cracking of the crankshaft.