Failure Analysis of a Surface Crack in E-Motor Shaft

The present work investigates a surface crack found in an input shaft of e-motor used for no-road applications such as electrical lawn mower and scissor lift applications. Detailed failure analysis was carried out involving visual inspection, chemical analysis, microstructural analysis, fractography, SEM and EDS analysis. The analysis concluded that the surface crack observed is due to the delay in tempering process. Experimental simulation was conducted to validate, and it revealed that the crack got developed in the as-quenched specimens when they were not immediately subjected to tempering process. It is recommended to carry out the tempering process right after quenching to avoid such kind of failures.