Metallography is the discipline of preparing and analyzing metal specimens to determine their structural characteristics. Technicians cut, mount, grind, polish, and etch samples to reveal phases, grain boundaries, and inclusions under a microscope. It is the primary diagnostic tool in heat treating for verifying case depths, confirming phase transformations, and investigating failures.
Send that cracked pinion to metallography so we can see if it was intergranular fracture.
The hardest part of metallography is sample preparation. A poor polish or over-etch will hide the very structures you are trying to see.
Related terms
Microstructure
The internal arrangement of phases and grains in a metal visible only under magnification.
Cut and etch
Shop phrase for sectioning a sample part and etching it to check case depth or structure.
Nital etch
An etch of nitric acid in alcohol that reveals steel microstructure and grinding damage.