GB/T 42785-2023 English PDF (GBT42785-2023)

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GB/T 42785-2023: Bearing steel wire rod
GB/T 42785-2023
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.60
CCS H 44
Bearing Steel Wire Rod
ISSUED ON: AUGUST 6, 2023
IMPLEMENTED ON: MARCH 1, 2024
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Terms and Definitions ... 6
4 Order Content ... 6
5 Dimensions, Appearance and Weight ... 7
6 Technical Requirements ... 7
7 Test Methods ... 10
8 Inspection Rules ... 12
9 Packaging, Marking and Quality Certificate ... 12
Appendix A (normative) Standard Diagrams of Macrostructure of Bearing Steel Wire
Rod ... 13
Appendix B (normative) Standard Diagram of Fine-grained Carbide Strip of Bearing
Steel Wire Rod ... 15
Bearing Steel Wire Rod
1 Scope
This document specifies the order content, dimensions, appearance, weight, technical
requirements, test methods, inspection rules, packaging, marking and quality certificate of
bearing steel wire rod.
This document is applicable to the production of bearing steel wire rod (hereinafter referred to
as the “wire rod”) with a diameter of 4.5 mm ~ 32.0 mm, such as: bearing rings and rolling
elements, etc.
2 Normative References
The contents of the following documents constitute indispensable clauses of this document
through the normative references in the text. In terms of references with a specified date, only
versions with a specified date are applicable to this document. In terms of references without a
specified date, the latest version (including all the modifications) is applicable to this document.
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 Aluminum 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 223.17 Methods for Chemical Analysis of Iron, Steel and Alloy - The Diantipyrylmethane
Photometric Method for the Determination of Titanium Content
GB/T 223.23 Iron, Steel and Alloy - Determination of Nickel Content - The Dimethylglyoxime
Spectrophotometric Method
GB/T 223.26 Iron, Steel and Alloy - Determination of Molybdenum Content - The Thiocyanate
Spectrophotometric Method
GB/T 223.29 Iron, Steel and Alloy - Determination of Lead Content - Carrier Precipitation-
xylenol Orange Spectrophotometric Method
GB/T 223.31 Iron, Steel and Alloy - Determination of Arsenic Content - Distillation-
molybdenum Blue Spectrophotometric Method
GB/T 223.47 Methods for Chemical Analysis of Iron, Steel and Alloy - The Carrier
GB/T 11261 Steel and Iron - Determination of Oxygen Content - The Pulse Heating Inert Gas
Fusion-infrared Absorption Method
GB/T 13298 Inspection Methods of Microstructure for Metals
GB/T 18254-2016 High-carbon Chromium Bearing Steel
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 20125 Low-alloy Steel - Determination of Multi-element Contents - Inductively Coupled
Plasma Atomic Emission Spectrometric Method
YB/T 5293 Metallic Materials - Forging Test
3 Terms and Definitions
This document does not have terms or definitions that need to be defined.
4 Order Content
The contracts or orders that purchase products in accordance with this document include, but
are not limited to the following content:
a) Serial No. of this document;
b) Product name;
c) Designation;
d) Specification;
e) Weight (or quantity);
f) Appearance;
g) Delivery state;
h) Purpose (if not specified, for rings);
i) Special requirements.
5 Dimensions, Appearance and Weight
5.1 The dimensions and allowable deviation of the wire rod shall comply with the stipulations
of Table 1. If there are special requirements, they shall be negotiated between the supply-side
and the demand-side and specified in the contract.
5.2 Appearance and Weight
5.2.1 Each coil consists of one wire rod and shall not have joints. The minimum weight of each
coil of wire rod shall be not less than 1,000 kg.
5.2.2 If there are special requirements, they shall be negotiated between the supply-side and the
demand-side and specified in the contract.
6 Technical Requirements
6.1 Designation and Chemical Composition
6.1.1 The designation and chemical composition (smelting analysis) of steel shall comply with
the stipulations of GB/T 18254-2016. The residual elements of wire rods used to make rings
shall comply with the stipulations of high-quality steel, high-grade high-quality steel, and
special-grade high-quality steel in GB/T 18254-2016. The residual elements of wire rods used
to make rolling elements shall comply with the stipulations of high-grade high-quality steel and
special-grade high-quality steel in GB/T 18254-2016.
6.1.2 The hydrogen content in steel shall not exceed 0.0002%.
6.1.3 The allowable deviation of the composition of finished steel products shall comply with
the stipulations of GB/T 18254-2016.
6.1.4 The wire rods shall be inspected one by one using the spark method or a spectroscope. If
the supply-side can guarantee it, the inspection is not required.
6.2 Smelting Method
accordance with 7.2.1 and be evaluated in accordance with 7.2.2.2. The qualification level shall
not be greater than Level 2.0.
6.7.3 Carbide elutriation
The carbide elutriation of the wire rods shall be subject to sampling and sample preparation in
accordance with 7.2.1 and be evaluated in accordance with 7.2.2.3. There shall be no carbide
elutriation.
6.8 Microstructure
The microstructure of the spheroidized annealed wire rods shall be a tiny, uniform and fully
spheroidized pearlitic structure, which shall be rated in accordance with the 5th rating diagram
of Appendix A in GB/T 18254-2016. Its qualification level is Level 2 ~ Level 4.
6.9 Micropore
The wire rods shall be subject to the micropore inspection in accordance with GB/T 18254-
2016. The wire rods shall manifest no micropores.
6.10 Decarburized Layer
The depth of the decarburized layer on the surface of the wire rods shall be inspected in
accordance with the metallographic method of GB/T 224. The total depth of the decarburized
layer on one side shall comply with the stipulations of Table 3.
6.11 Grain Size
The qualification level of austenite grain size of the wire rods shall be Level 8 or finer specified
in GB/T 6394.
6.12 Surface Quality
The head and tail defects of the wire rods shall be removed, and there shall be no defects, such
as: cracks, folds, scars, ears and delamination on the surface. Local indentations, bumps, pits,
scratches and pitting, etc. are allowed, but their depth or height shall comply with the
stipulations of Table 4.
7 Test Methods
7.1 Chemical Composition
The chemical analysis method shall comply with the universal methods in GB/T 223.5, GB/T
223.9, GB/T 223.11, GB/T 223.17, GB/T 223.23, GB/T 223.26, GB/T 223.29, GB/T 223.31,
GB/T 223.47, GB/T 223.50, GB/T 223.53, GB/T 223.59, GB/T 223.62, GB/T 223.63, GB/T
223.77, GB/T 223.82, GB/T 223.85, GB/T 223.86 or GB/T 4336, GB/T 11261, GB/T...