SAE ARP 1820C:2021-05-19

This practice provides a method for evaluating microhardness and microstructure very close (0.002 inch (0.051 mm) or less) to the surface of a disk specimen. Specific accept/reject criteria for partial decarburization (3.7.1), inadvertent carburization/nitriding (3.7.3), total decarburization/intergranular oxidation (3.8), and other characteristics evaluated are to be found in the applicable specification where this ARP is referenced.