1.1 This specification covers chemical and mechanical requirements for eight property classes of hex and hex-flange carbon and alloy steel nuts for general structural and mechanical uses on bolts, studs, and other externally threaded parts.

Note 1—Throughout this specification, the term class means property class.

Note 2—Requirements for the four classes 5, 9, 10, and 12 are essentially identical with requirements given for these classes in ISO 898/II. Requirements for Classes 8S and 10S are essentially identical with requirements in an ISO 4775 Hexagon Nuts for High-Strength Structural Bolting with Large Width Across Flats, Product Grade B, Property Classes 8 and 10. Classes 8S3 and 10S3 are not recognized in ISO standards.

1.2 Classes 8S3 and 10S3 nuts have atmospheric corrosion resistance and weathering characteristics comparable to those of the steels covered in Specification A 588/A 588M. The atmospheric corrosion resistance of these steels is substantially better than that of carbon steel with or without copper addition (see 5.2). When properly exposed to the atmosphere, these steels can be used bare (uncoated) for many applications.

1.3 The nut size range for which each class is applicable is given in the table on mechanical requirements.

1.4 Appendix X1 gives guidance to assist designers and purchasers in the selection of a suitable class.

1.5 Appendix X2 gives data on the properties of slotted hex nuts and hex jam nuts.

Note 3—This specification is the metric companion of Specification A 563.

1.6 Terms used in this specification are defined in Terminology F 1789 unless otherwise defined herein.

ASTM Standards

A153/A153M Specification for Zinc Coating (Hot-Dip) on Iron and Steel Hardware
A325M Specification for Structural Bolts, Steel, Heat Treated 830 MPa Minimum Tensile Strength (Metric)
A394 Specification for Steel Transmission Tower Bolts, Zinc-Coated and Bare
A490M Specification for High-Strength Steel Bolts, Classes 10.9 and 10.9.3, for Structural Steel Joints (Metric)
A588/A588M Specification for High-Strength Low-Alloy Structural Steel, up to 50 ksi [345 MPa] Minimum Yield Point, with Atmospheric Corrosion Resistance
A751 Test Methods, Practices, and Terminology for Chemical Analysis of Steel Products
B695 Specification for Coatings of Zinc Mechanically Deposited on Iron and Steel
D3951 Practice for Commercial Packaging
F568M Specification for Carbon and Alloy Steel Externally Threaded Metric Fasteners (Metric)
F606M Test Methods for Determining the Mechanical Properties of Externally and Internally Threaded Fasteners, Washers, and Rivets (Metric)
F812/F812M Specification for Surface Discontinuities of Nuts, Inch and Metric Series
F1789 Terminology for F16 Mechanical Fasteners
G101 Guide for Estimating the Atmospheric Corrosion Resistance of Low-Alloy Steels

ANSI Standards

B18.2.4.6M Metric Heavy Hex Nuts

ISO Standards

ISO4775 Hexagon Nuts for High-Strength Structural Bolting with Large Width Across Flats--Product Grade B--Property Classes 8 and 10