scope:

This standard establishes requirements and tests for performing temper etch inspection of carburized steels and tool and low alloy steels which are heat treated above 1.24 × 10⁹ Pascal (PA) [1.26 × 10² kilogram-force/square millimeter (Kgf/mm²) 1.8 × 10⁵ pound-force/square inch (psi)].

This standard applies to aircraft and missiles structural and propulsion system components when MIL-I-6870 and/or MIL-STD-866 are referenced as an item specification in the contract or order.

Temper etch inspection is typically performed on steels from the following groups:

Group A - Low alloy steels - SAE 52100, SAE 4140, SAE 4330, SAE 4340, 300M, D6AC, 440C, etc. Carburizing Steels - SAE 4620, 9310, AMS 6260, etc. Group B - Tool steels - H-11, M-50, M-2, H-13, etc.

This standard is not applicable to surface hardened steels produced by nitriding or carbonitriding.

This inspection is to be conducted to determine if heat has been induced in a component, subsequent to final heat treat, by machining, grinding, or other means which will adversely affect the required properties of that component.

To detect localized discontinuous carburization due to an inadvertent carburize stop-off and to determine the presence of or lack of total carburization in specified locations.

To detect a decarburized surface layer.