Steel HP 9-4-25 AMS Number Alloy Type UNS Cross Ref. Spec Misc./Shape AMS 6546 HP 9-4-25 Steel K91122 AMS 6546 Plate HP 9-4-25 Steel K91122 - Plate AMS 6546 Sheet HP 9-4-25 Steel K91122 - Sheet AMS 6546 Strip HP 9-4-25 Steel K91122 - Strip