This standard specifies the mechanical properties of nuts made of austenitic, martensitic and ferritic grades of corrosion-resistant stainless steels when tested over an ambient temperature range of 15~25℃. Properties will vary at higher or lower temperatures.
It applies to nuts:
With nominal thread diameters D≤39mm;
Common threads in accordance with GB/T 192;
Diameter and pitch combination in accordance with GB/T 193;
Basic tolerance specified in GB/T 197;
Of any shape;
With width across flats as specified in GB/T 3104;
With nominal heights ≥0.5D.
It does not apply to nuts requiring properties such as:
Locking abilities;
Weldability.
The corrosion or oxidation resistance in particular environments.
The aim of this standard is a classification into property classes of corrosion resistant stainless steel fasteners. Some materials can be used at temperatures down to -200℃, some can be used at temperatures up to +800℃ in air. Information on the influence of temperature on mechanical properties is found in Appendix D (Informative).
Corrosion and oxidation performances and mechanical properties for use at elevated or sub-zero temperatures must be the subject of agreement between user and manufacturer in each particular case. Appendix (Informative) E shows how the risk of intergranular corrosion at elevated temperatures depends on the carbon content.
All austenitic stainless steel fasteners are normally non-magnetic in the annealed condition; after cold working, some magnetic properties may be evident, see Appendix F (Informative).
2 Normative References
The following standards contain provisions which, through reference in this text, constitute provisions of this standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below.
GB/T 192-1981 General Purpose Metric Screw Threads - Basic Profile
GB/T 193-1981 General Purpose Screw Threads - Diameters and Pitches
GB/T 196-1981 General Purpose Screw Threads - Basic Dimensions for Diameter from 1 to 600mm
GB/T 197-1981 General Purpose Screw Threads - Tolerances and Fits for Diameter from 1 to 355mm
GB/T 230-1991 Metallic Materials - Rockwell Hardness Test
GB/T 231-1984 Metallic Materials - Brinell Hardness Test
GB/T 3098.2-2000 Mechanical Properties of Fasteners - Nuts - Coarse Thread (idt ISO 898-2:1992)
GB/T 3098.4-2000 Mechanical Properties of Fasteners - Nuts - Fine Pitch Thread (idt ISO 898-6:1994)
GB/T 3104-1982 Fasteners; Widths across Flats of Hexagon Products (eqv ISO 272:1982)
GB/T 4340.1-1999 Metallic Materials - Vickers Hardness Test - Part 1:Test Method (eqv ISO 6507-1:1997)
ISO 683-13:1986 Heat-treatable Steels, Alloy Steels and Free-cutting Steels - Part 13: Wrought Stainless Steels
ISO 3651-1:1976 Determination of Resistance to Intergranular Corrosion Stainless Steels - Part 1: Austenitic and Ferritic-austenitic (Duplex) Stainless Steels - Corrosion Test in Nitric Acid Medium by Measurement of Loss in Mass (to be Published)
(Huey test).
ISO 3651-2:1976 Determination of Resistance to Intergranular Corrosion Stainless Steels - Part 2: Ferritic, Austenitic and Ferritic-austenitic (Duplex) Stainless Steels - Corrosion Test in Media Containing Sulfuric Acid (to be Published)
ISO 4954:1993 Steels for Cold Heading and Cold Extruding
3 Designation, Marking and Finish
3.1 Designation
The designation system for stainless steel grades and property classes for nuts is shown in Figure 1. The designation of the material consists of two blocks which are separated by a hyphen. The first block designates the steel grade, the second block the property class.
GB/T 3098.15-2000 The following standards are cited：
