Form This specification covers a nitriding grade of aircraft-quality@ low-alloy steel in the form of bars@ forgings@ mechanical tubing@ and forging stock. AMS6497 and AMS6498 cover UNS K23280 having other quality levels. Application These products have been used typically for nitrided parts such as bearings@ operating under heavy loads and high speeds at moderate temperatures@ and subject to rigid inspection standards@ and requiring highest surface hardness@ high core toughness@ and less distortion than parts made from steel requiring quenching to case harden@ but usage is not limited to such applications.