Failure Analysis of Engine Block of 6.2 MW DG set of Hindustan Glass Ltd.

Abstract

Failure analysis of gears and bush from the engine block of 6.2 MW DG set has been carried out by optical micro-scopy, SEM fractography, microhardness profie across and case and core, EDS microanalysis, etc. The study revealed that there was some misalignment in the engine block which resulted in overloading of the localised region on the face of the gear surface. This resulted in macropitting damage at the localised regions of the gear face. Profuse pitting both micro and macro was observed on the tooth face regions in the addendum regions while no pitting was observed in the flank area. The damage mechanism was identified to be due to surface contact fatigue. The gear material was found to be perfectly all right from micro-structure and hardness point of view. The teeth material (hardened case) was subjected to a stress in service more than ultimately led to surface contact fatigue cracking. Moreover, the extensive plastic deformation of the bush also manifest overload which might have been caused by the misalignment. This damage occured over a period of time rather than instantly.