ABSTRACT
A failure mechanism is simply the way in which a system or component might fail whilst in service use. In general, stresses imposed on any product during the course of its lifetime can be grouped as mechanical, thermal, chemical, environmental, biological, electrical and misuse or abuse. Stress corrosion cracking is a phenomenon related to a combination of static tensile stress along with a corrosive environment. Fracture toughness of a material denotes the intensity of stress required to grow a pre-existing defect or flaw. Observation under low-power magnification revealed that the fracture surface of two separate gear teeth contained classic beach-marking features, providing a fingerprint of a fatigue fracture mechanism having been at play. The minimum number of stress cycles a fractured component has been subjected to can be approximated by estimating the number of striations on the critical part of the fracture surface.
