scope:

1. (a) This specification covers alloy-steel bolting material specially heat treated for high-temperature service, such as steam turbine, gas turbine, and similar uses. This material requires special processing and should not be used in general-purpose applications. The term "bolting material", as used in this specification, covers rolled or forged bars, bolts, nuts, screws, washers, studs, and stud bolts.

(b) The high-temperature properties of the material covered by this specification are dependent upon special heat treatment which is required. Although the high-temperature properties are not specified, they are implied by control of the chemistry, heat treatment, and room-temperature properties of the material.

Note 1.-High-temperature tests shall not be required, unless made a matter of agreement between the manufacturer and the purchaser.

(c) Two levels of bolting strength are covered, designated grades B4B and B4C. Selection will depend on the design and the stresses and service for which the product is to be used.

NOTE 2.-Bolting material is also covered by the following ASTM specifications: ASTM Designations A 193, A 307, A 320, A 325, and A 354. Reference should be made to these specifications for grades of carbon- and alloy-steel bolting material for use at temperatures lower than the range intended for the material covered in this specification.

NOTE 3.-When ordering material under this specification, or when incorporating this specification as a reference in any individual specification, the purchaser must designate the steel by identification symbol or analysis, or both, and definitely specify the minimum mechanical properties required as selected from Table II.