Steel CBS 600 AMS Number Alloy Type UNS Cross Ref. Spec Misc./Shape AMS 6255 CBS 600 Steel K21940 AMS 6255 Bar CBS 600 Steel K21940 - Bar AMS 6255 Forging CBS 600 Steel K21940 - Forging AMS 6255 Tubing CBS 600 Steel K21940 - Tubing