Analysis of Fractures Utilizing the SEM

Abstract

The Scanning Electron Microscope (SEM), a versatile and useful tool for failure analysis investigations, has since the early 1960’s steadily replaced the transmission electron microscope (TEM) for fracture surface analysis. This instrument is particularly useful in fracture analysis because (1) it extends in useful magnification from the light microscopescope to that of the TEM, and (2) fractures are viewed directly, eliminating the tedious and time-consuming replication process required for TEM examination. With this instrument, an experienced engineer can determine the mode of failure of a broken part in a relatively short period of time. By itself, however, the SEM cannot uncover all the facts leading to the identification of the cause of a component failure. Most often, it offers enough information about a failure so that together with other test results, a more complete understanding of the cause of failure is determined. This paper illustrates the usefulness of SEM in the analysis of fractures and the importance of correlating other test results, such as a light microscope fracture surface examination and metallographic examination, with SEM results to determine a cause of failure.