Metallography

Metallography is a metallurgical testing procedure that allows the observer, with the aid of a metallurgical or digital microscope , to examine the "internal structure" of a piece of metal. The internal structure will reveal the microstructure (how the metal grains are arranged and their size), impurities (such as non-metallic inclusions), any crack development and progression and the existence of cold work and grain boundary precipitates, etc.

A sample of the metal of interest is cut, mounted (sometimes a metallographic examination is performed without mounting), and the surface is polished to a mirror finish. The polished surface is often examined in the polished condition. However, additional microstructural details are revealed by etching (usually with a dilute acid) to reveal the etched microstructure.