OS11. Metallographic examination

Metallography requires the removal of small samples, which are then mounted in a resin or bakelite block, polished and etched in dilute acid, before examination under a metallurgical microscope. This reveals the crystal structure of the metal, from which an assessment of the type of alloy and its mechanical and heat treatment history can be made. Metallography thus provides a good measure of the quality of the metal and its suitability for a particular application. Scott (1991) provides a good introduction to the structure of metals, metallography and the phase diagrams which help explain the microstructures it reveals.