Rear Axle Failure Analysis of the Dump Truck

Abstract

The dump truck rear axle has failed while operating. The shaft transmits torque from the differential gear to the rear wheels through a planetary gear arrangement. Axle parts that fail to be investigated to determine the cause of failure. Field scanning is done using scanning electron microscopy (SEM). The hardness profile along the cross section is evaluated by measurement of micro hardness. Chemical analysis shows that the shaft is made of american iron steel institude (AISI) 4140 steel. The shaft carbon content is 0.52%, higher than AISI 4140 standard where the maximum carbon content is 0.45%. Manganese (Mn), sulfur (S), phosphorus (P), silicon (Si), and chromium (Cr) content have met standards. Microstructure analysis and profile hardness testing revealed that the edge profile was more fragile, different from the more resilient core. This phenomenon is related to the discovery of microstructure on the edge of the profile found in a martensitic structure which reveals that the manufacturing of the shaft undergoes a surface hardening process to harden the shaft surface. The analysis shows that the fracture starts from the edge of the profile where there is a fragile martensitic structure due to improper heat treatment (high hardness).