Reasons Analysis on Surface Cracks of a Heavy Marine Crankshaft

Cracks were exposed on surface of a heavy marine crankshaft after shrink fitting and polishing. By means of macroscopic examination, chemical compositions analysis, mechanical properties test, metallographic examination, SEM analysis and fracture oxidation simulated experiment, cracks formation causes of the crankshaft were analyzed. The results show that the cracks were caused by the large surface tensile stress and deteriorative surface microstructure formed during the gas cutting process.