"STEEL,ALLOY,FORGING AISI 4140 PERMIL-S-46172 GRADE D OPTL:STEEL,ALLOY; BAR AISI 4140 SPEC ASTM A322,A331; QUENCH AND TEMPER TO RHC 32-38; HEAT TREAT: NITRIDE SURFACE D ALL OTHER SURFACES OPTL.CASE CHARACTERISTICS: EFFECTIVE DEPTH: 0.010 MIN.EFFECTIVE DEPTH IS DEPTH OF CASE AT RHC 47"