GB/T 28906-2025 Hot-rolled steel wire rod for cold heading
1 Scope
This document specifies the classification and designation system, order information, manufacturing processes, technical requirements, test methods, inspection rules, and packaging, marking and certification for hot-rolled steel wire rods for cold heading.
This document is applicable to hot-rolled steel wire rods for cold heading (hereinafter referred to as "wire rods") with nominal diameters ranging from 5mm to 52mm, which are intended for manufacturing fasteners such as bolts, screws, and studs, as well as for steel wires for cold heading. For wire rods exceeding the specified size range, this document may still be referenced for guidance.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions 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 222 Permissible tolerances for chemical composition of steel products
GB/T 223.5 Steel and iron - Determination of acid-soluble silicon and total silicon content - Reduced molybdosilicate spectrophotometric method
GB/T 223.9 Iron, steel and alloy - Determination of aluminium content - Chrome azurol S photometric method
GB/T 223.11 Iron, steel and alloy - Determination of chromium content - Visual titration or potentiometric titration method
GB/T 223.12 Methods for chemical analysis of iron, steel and alloy - The sodium carbonate separation - Diphenyl carbazide photometric method for the determination of chromium content
GB/T 223.14 Methods for chemical analysis of iron, steel and alloy - The N-benzoyl-N-phenylhydroxylamine extraction photometric method for the determination of vanadium content
GB/T 223.26 Iron, steel and alloy - Determination of molybdenum content - The thiocyanate spectrophotometric method
GB/T 223.37 Iron, steel and alloy - Determination of nitrogen content - Indophenol blue spectrophotometric method after distillation separation
GB/T 223.40 Iron, steel and alloy - Determination of niobium content by the sulphochlorophenol S spectrophotometric method
GB/T 223.53 Methods for chemical analysis of iron, steel and alloy - The flame atomic absorption spectrophotometric method for the determination of copper content
GB/T 223.54 Iron, steel and alloy - Determination of nickel content - Flame atomic absorption spectrometric method
GB/T 223.59 Iron, steel and alloy - Determination of phosphorus content - Bismuth phosphomolybdate blue spectrophotometric method and antimony phosphomolybdate blue spectrophotometric method
GB/T 223.60 Iron, steel and alloy - Determination of silicon content - Gravimetric method
GB/T 223.63 Iron, steel and alloy - Determination of manganese content - Sodium (potassium) periodate spectrophotometric method
GB/T 223.78 Methods for chemical analysis of iron, steel and alloy - Curcumin spectrophotometric method for the determination of boron content
GB/T 223.79 Iron and steel - Determination of multi-element contents - X-ray fluorescence spectrometry (Routine method)
GB/T 223.81 Iron, steel and alloy - Determination of total aluminum and total boron contents - Microwave digestion-inductively coupled plasma mass spectrometric method
GB/T 223.84 Steel, iron and alloy - Determination of titanium content - Diantipyrylmethane spectrophotometric method
GB/T 223.85 Steel and iron - Determination of sulfur content - Infrared absorption method after combustion in an induction furnace
GB/T 223.86 Steel and iron - Determination of total carbon content - Infrared absorption method after combustion in an induction furnace
GB/T 224 Determination of depth of decarburization of steels
GB/T 225 Steel - Hardenability test by end quenching (Jominy test)
GB/T 226 Test method for macrostructure and defect of steel by etching
GB/T 228.1 Metallic materials - Tensile testing - Part 1: Method of test at room temperature
GB/T 229 Metallic materials - Charpy pendulum impact test method
GB/T 230.1 Metallic materials - Rockwell hardness test - Part 1: Test method
GB/T 1979 Standard diagrams for macrostructure and defect of structural steels
GB/T 2101 General requirement of acceptance, packaging, marking and certification for section steel
GB/T 2975 Steel and steel products - Location and preparation of samples and test pieces for mechanical testing
GB/T 4336 Carbon and low-alloy steel - Determination of multi-element contents - Spark discharge atomic emission spectrometric method (routine method)
GB/T 6394 Determination of estimating the average grain size of metal
GB/T 8170 Rules of rounding off for numerical values & expression and judgment of limiting values
GB/T 10561-2023 Determination of content of nonmetallic inclusions in steel - Micrographic method using standard diagrams
GB/T 14981-2009 Dimension, shape, mass and tolerance for hot-rolled round wire rod
GB/T 17505 Steel and steel products - General technical delivery requirements
GB/T 20066 Steel and iron - Sampling and preparation of samples for the determination of chemical composition
GB/T 20123 Steel and iron - Determination of total carbon and sulfur content - Infrared absorption method after combustion in an induction furnace (routine method)
GB/T 20124 Steel and iron - Determination of nitrogen content - Thermal conductimetric method after fusion in a current of inert gas (routine method)
GB/T 20125 Low-alloy steel - Determination of multi-element contents - Inductively coupled plasma atomic emission spectrometric method
GB/T 21834 Medium and low alloy steel - Determination of the distribution of multi-element contents - Original position statistic distribution analysis method
GB/T 22368 Low-alloy steel - Determination of multi-element contents - Glow discharge optical emission spectrometry (Routine method)
YB/T 5293 Metallic materials - Forging test
3 Terms and definitions
No terms or definitions are listed in this document.
4 Classification and designation system
4.1 Classification
This document categorizes steel wire rods into four types based on their application states: non-heat-treated, surface hardened, quenched and tempered (including boron-containing steels), and non-quenched and tempered types.
4.2 Designation system
4.2.1 Non-heat-treated, surface hardened, and quenched and tempered types (including boron-containing steels)
The grade designations for these steel types consist of three parts: The initials "ML" of the Chinese pinyin for "Mao Luo" meaning "fastener/cold heading steel", the average carbon content, and the principal alloying elements.
Example:
ML20MnTiB
Where,
ML——the initials of the Chinese pinyin for "Mao Luo";
20——the average carbon content (expressed in ten-thousandths);
MnTiB——the principal alloying elements.
4.2.2 Non-quenched and tempered type
The grade designations for non-quenched and tempered steels consist of four parts: The initial "M" of the Chinese pinyin for "Mao" meaning "fastener", the initials "FT" of the Chinese pinyin for "Fei Tiao" meaning "non-quenched and tempered", the fastener strength grade, and the Chinese pinyin representing the dominant microstructure. Among them, the Chinese Pinyin letters representing the dominant microstructure are as follows: Ferrite-pearlite (base type) without additional letters; ferrite-bainite type with letter "B"; granular bainite type with letters "LB"; ferrite-martensite duplex steel with letters "DP".
Example:
MFT8B
Where,
M——the initial of the Chinese pinyin for "Mao";
FT——the initials of the Chinese pinyin for "Fei Tiao";
8——the strength grade number of the fastener;
B——the dominant microstructure of ferrite-bainite.
Contents
1 Scope
2 Normative references
3 Terms and definitions
4 Classification and designation system
5 Order information
6 Manufacturing processes
7 Technical requirements
8 Test methods
9 Inspection rules
10 Packaging, marking and certification
Annex A (Informative) Comparison between designations in this document and relevant standards
Annex B (Informative) Mechanical properties of heat-treated specimens
Annex C (Informative) Special quality inspections
Bibliography
