This specification covers the chemical and mechanical requirements of quenched and tempered alloy steel bolts, studs, and other externally threaded fasteners. All fasteners shall be made from alloy steel conforming to the chemical composition requirements. Two levels of bolting strength are covered, designated Grades BC and BD. Selection will depend upon design and the stresses and service for which the product is to be used. Hardness, tensile strength, yield strength, elongation, and area reduction shall be tested to meet the requirements prescribed.

1.1 This specification2 covers the chemical and mechanical requirements of quenched and tempered alloy steel bolts, studs, and other externally threaded fasteners 4 in. and under in diameter for application at normal atmospheric temperatures, where high strength is required and for limited application at elevated temperature (Note 1). Any alloy steel capable of meeting the mechanical and chemical properties set forth in this specification may be used.

Note 1: For bolts, studs, or other externally threaded fasteners, to be used at elevated temperatures, refer to Specification A193/A193M.

1.2 Two strength levels are covered, designated Grades BC and BD. Selection will depend upon design and the stresses and service for which the product is to be used.

Note 2: Quenched and tempered alloy steel bolts for structural steel joints up through 1¹/₂ in. in diameter are covered in Specification F3125/F3125M. For fastener diameter sizes above 1 ¹/₂ in., Grade BC may be considered for structural steel bolting where tensile strength above 120 ksi is necessary and Grade BD may be considered for structural steel bolting where tensile strength above 150 ksi is necessary. In this event, additional requirements of Specification F3125/F3125M, such as head size, lubricant, and magnetic particle inspection, should be carefully considered.

1.3 Nuts are covered in Specification A563. Unless otherwise specified, the grade and style of nut for each grade of fastener shall be as follows:

 
Grade of Fastener and Surface Finish

Nut Grade and
Style^A

BC, plain (or with a coating of insufficient thick-
 ness to require over-tapped nuts)

  C, heavy hex

BC, zinc-coated (or with a coating thickness re-
 quiring over-tapped nuts)

  DH, heavy hex

BD, all finishes

 DH, heavy hex

1.4 Optional supplementary requirements are provided at the end of this standard.

1.5 Terms used in this specification are defined in Terminology F1789 unless otherwise defined herein.

1.6 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard.

1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.