Failure Analysis of Metallic Materials: Morphological Characteristics, Mechanisms and Laboratory Investigation

Abstract

Morphological analysis, characteristics and modes/mechanisms of metallic materials (components) failure particularly in service have been reviewed and discussed. Firstly, the various investigation steps and analytical methods are expressed, while various failure examples are discussed. The investigation techniques range from visual inspection, non-destructive testing to electron microscopy and chemical analysis methods. Secondly, laboratory investigative analysis of failed Al wire of 1120 grade was performed with scanning electron microscopy and energy dispersive spectroscopy (EDS) techniques to reveal availability of second-phase particles (impurities) at representative areas of interest for the largest open microscopic failure and inside surface feature of the failed Al wire at different locations inside and near the edge of the failed cracks. The mode of failure was determined to be brittle failure, while the surrounding matrix presents a feature of mixed brittle and ductile failure. EDS analysis shows O2 in addition to the base Al which is an indication of Al2O3. The peak for Cl was also present. This impurity within the aluminium matrix is responsible for weakening the Al substrate structure which yields under high stress.