Form: This specification covers a free-machining@ low-alloy steel in the form of round bars 3.50 inches (88.9 mm) and under in nominal diameter. Application: Primarily for parts@ such as shafts@ axles@ pins@ fasteners@ gears@ and screw machine parts@ which are normally used at hardness of 30- 36 HRC and which do not require a high degree of ductility.