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

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

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GB/T 42785-2023: Bearing steel wire rod

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.
GB/T 42785-2023
GB
NATIONAL STANDARD OF THE
PEOPLE 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 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 20123, GB/T 20125, etc. The arbitration shall be conducted in accordance with 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, GB/T 11261, GB/T 20123, GB/T 20125. 7.2 Carbide Heterogeneity
7.2.1 Specimen selection
In accordance with the stipulations of GB/T 18254-2016, conduct sampling and sample preparation.
7.2.2 Rating method
7.2.2.1 Carbide network
Rate in accordance with the 6th rating diagram in Appendix A of GB/T 18254-2016. 7.2.2.2 Carbide strip
7.2.2.2.1 Adopt the 8th rating diagram in Appendix A of GB/T 18254-2016. In accordance with the 100-times rating diagram, evaluate the width of the carbide strip. In combination with the 500-times rating diagram, comprehensively determine the carbide aggregation degree and particle size.
7.2.2.2.2 If a carbide strip has different widths, the widest point shall be used as the width of the carbide strip. When multiple carbide strips appear in the field of view and run through the field of view, the most severe carbide strip shall be considered as the carbide strip level of the field of view. When several strips of carbide intersect together, the maximum width shall be 8 Inspection Rules
8.1 Inspection and Acceptance
The wire rods shall be subject to quality inspection and acceptance inspection by the supply- side?€?s quality supervision department. The demand-side has the right to conduct acceptance inspection in accordance with the stipulations of this document.
8.2 Batch Rules
The wire rods shall be inspected and accepted in batches. Each batch shall be composed of wire rods of the same heat No., designation, dimensions, rolling system and heat treatment system. 8.3 Re-inspection and Determination Rules
8.3.1 Among all inspection items, if any inspection item is disqualified (except for white spots and non-metallic inclusions), re-sampling can be carried out for a re-inspection of the disqualified item, and the sampling quantity shall be the same as that of the initial inspection (except for oxygen content). If it is qualified in the re-inspection, then, the batch of wire rods shall be determined as qualified; if it still fails the re-inspection, then, the batch of wire rods shall be determined as disqualified.
8.3.2 When the oxygen content is disqualified, 3 specimens can be randomly taken from different coils of wire rods for a re-inspection. The average value of the inspection results shall be not greater than the value specified in this document. One specimen is allowed to exceed the value specified in this document, but it shall not exceed the value in this document plus 0.0003%. 8.3.3 If the quantity of specimens that fail the initial inspection exceeds half of the specimens being inspected, it suggests that the quality of this batch of wire rods is poor, then, the re- inspection shall not be conducted, so as to ensure the quality of the delivered wire rods. However, the supply-side can re-process and group the wire rods as a new batch for inspection and acceptance inspection.
9 Packaging, Marking and Quality Certificate
The packaging, marking and quality certificate shall comply with the stipulations of GB/T 2101.

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