This specification covers the chemical and mechanical requirements for style 1 stainless steel metric nuts. Groups and property classes of austenitic, ferritic, martensitic, and precipitation hardening stainless steel alloys are covered. Materials shall be cold-formed, hot-formed, or machined form, and shall conform to chemical, mechanical, dimensional and surface finish properties. Stainless steel shall also conform to heat treatment requirements depending on material grade. The material shall be capable of passing chemical, mechanical, and corrosion resistance tests in accordance to the specification. Product marking and packaging shall conform to the requirements of the specification.

1.1 This specification covers the chemical and mechanical requirements for stainless steel metric nuts with nominal thread diameters M1.6 through M36 and intended for use in engineering applications requiring general corrosion resistance.

1.2 Eight groups of stainless steel alloys are covered, including three austenitic (Grades A1, A2, and A4), one ferritic (Grade F1), three martensitic (Grades C1, C3, and C4), and one precipitation hardening (Grade P1).

1.3 Seventeen property classes are covered, including nine austenitic, one ferritic, six martensitic, and one precipitation hardening. The property classes with the permissible alloys for each are listed in Table 1.

1.4 This specification is based in concept and content on ISO 3506. The chemical and mechanical requirements specified for all property classes, except as given in 1.4.1, are essentially identical with classes of the same designation in ISO 3506.

1.4.1 This specification includes 13 of the 16 property classes covered in ISO 3506. Additionally, it includes property classes A1-70, A2–70, A4–70, A1–80, A2–80, and A4–80 for products with nominal thread diameters larger than M20; and four non-ISO property classes, C1-110, C4-110, C3-120, and P1-90.

1.5 Supplementary requirements of an optional nature are provided, applicable only when agreed upon between the manufacturer and the purchaser at the time of the inquiry and order.

1.6 Suitable bolts, hex cap screws, and studs for use with nuts included in this specification are covered by Specification F738M. Unless otherwise specified, all bolts, hex cap screws, and studs used with these nuts shall conform to the requirements of Specification F738M and shall be of the same alloy group.

1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.