This standard specifies standard procedures and requirements for the detection and classification of localized overheating on ground surfaces by chemical etch methods.

Some methods which have been used in the past are no longer recommended. Specifications should be changed to use the methods in this standard. These etching methods are more sensitive to changes in surface hardness than most hardness testing methods.

This standard applies to steel parts, such as gears, shafts, splines and bearings, but is not applicable to nitrided parts and stainless steels.

NOTE: This process, although at times called “nital etch”, should notbeconfusedwith other processes also known as "nital etc".

The surface temper etch procedure is to be per- formed after grinding and before additional finishing operations.