This specification covers a premium aircraft-quality, low alloy-steel in the form of bars, forgings, mechanical tubing, and forging stock.

These products have been used for critical carburized parts, such as bearings, gears, and shafts, requiring high minimum core hardness with in a narrow range, good resistance to elevated temperature up to 600 \mDF (316 \mDC), and subject to very rigid magnetic particle inspection standards, but usage is not limited to such applications.