1.1 This specification covers alloy steel bars, suitable for surface hardening by nitriding, designated as Classes A, B, C, and D. Class A and Class D bars are general-purpose bars; Class B bars are free-machining bars; Class C bars contain 3.50 % nickel and are characterized by higher core strength. All classes are normally furnished in the hot-rolled, quenched, and tempered condition. However, centerless-ground or turned bars, in any of the classes, may be specified by the purchaser. Also, as-rolled, annealed, or unannealed bars suitable for forging may be purchased to this specification. When as-rolled, annealed, or unannealed bars are furnished, Sections 6, 10, and 11 are not applicable.

1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.