1 Scope
This part of GB/T 3098 specifies the mechanical properties of nuts made of austenitic, martensitic and ferritic steel grades of corrosion-resistant stainless steels, when tested over an ambient temperature range of 10℃~35℃. Properties vary at higher or lower temperatures.
This part applies to nuts:
——With nominal thread diameter D≤39 mm;
——Of general purpose thread with diameters and pitches in accordance with GB/T 192, GB/T 193 and GB/T 9144;
——Of any shape;
——With width across flats as specified in GB/T 3104;
——With nominal heights m ≥0.5D.
It does not apply to nuts requiring properties such as:
——Locking abilities, and
——Weldability.
Note: The designation system of this part can be used for sizes outside the limits given in this Clause (e.g. D > 39 mm), provided that all applicable mechanical and physical requirements of the property classes are met.
This part does not define corrosion or oxidation resistance in particular environments. However, some information on materials for particular environments is given in Annex D. Regarding definitions of corrosion and corrosion resistance, see GB/T 10123.
The aim of this part is the classification of corrosion-resistant stainless steel nuts into property classes. 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 Annex E.
Corrosion and oxidation performances and mechanical properties for use at elevated or sub-zero temperatures can be agreed on between the user and the manufacturer in each particular case. Annex F 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 can be evident (see Annex G).
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 90.3 Fasteners - Quality Assurance System (GB/T 90.3-2010, ISO 16426: 2002, IDT)
GB/T 192 General Purpose Metric Screw Threads-Basic Profile(GB/T 192-2003, ISO 68-1: 1998, MOD)
GB/T 193 Purpose Metric Screw Threads - General Plan (GB/T 193-2003, ISO 261: 1998, MOD)
GB/T 230.1 Metallic Materials - Rockwell Hardness Test - Part 1: Test Method (Scales A, B, C, D, E, F, G, H, K, N, T) (GB/T 230.1-2009, ISO 6508-1: 2005, MOD)
GB/T 231.1 Metallic Materials - Brinell Hardness Test - Part 1: Test Method(GB/T 231.1-2009, ISO 6506-1: 2005, MOD)
GB/T 3098.2 Mechanical Properties of Fasteners-Nuts-Coarse Thread
GB/T 3104 Fasteners - Widths across Flats of Hexagon Products(GB/T 3104-1982,, eqv ISO 272: 1982)
GB/T 4334 Corrosion of Metals and Alloys - Test Methods for Intergranular Corrosion of Stainless Steels (GB/T 4334-2008, ISO 3561-1: 1998 & ISO 3561-2: 1998, MOD)
GB/T 4340.1 Metallic Materials-Vickers Hardness Test - Part 1: Test Method(GB/T 4340.1-2009, ISO 6507-1: 2005, MOD)
GB/T 5267.4 Passivation of Corrosion-Resistant Stainless-Steel Fasteners(GB/T 5267.4-2009, ISO 16048: 2003, IDT)
GB/T 9144 General Purpose Metric Screw Threads - Preferable Plan(GB/T 9144-2003, ISO 262: 1998, MOD)
3 Symbols
D Nominal thread diameter
m Height of the nut (nominal value)
P Pitch of the thread
ReL Lower yield strength
Rm Tensile strength
Rp0.2 Stress at 0.2% plastic elongation
Foreword I
1 Scope
2 Normative References
3 Symbols
4 Designation, Marking and Finish
4.1 Designation
4.2 Marking
4.3 Finish
5 Chemical Composition
6 Mechanical Properties
7 Test Methods
7.1 Hardness HB, HRC or HV
7.2 Proof Load
Annex A (Informative) Description of the Groups and Grades of Stainless Steels
Annex B (Informative) Stainless Steel Composition Specifications
Annex C (Informative) Stainless Steels for Cold Heading and Extruding
Annex D (Informative) Austenitic Stainless Steels with Particular Resistance to Chloride Induced Stress Corrosion
Annex E (Informative) Mechanical Properties at Elevated Temperatures; Application at Low Temperatures
Annex F (Informative) Time-Temperature Diagram of Intergranular Corrosion in Austenitic Stainless Steels, Grade A2 (18/8 Steels)
Annex G (Informative) Magnetic Properties for Austenitic Stainless Steels
Bibliography
