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GB/T 38885-2020 English PDF (GBT38885-2020)

GB/T 38885-2020 English PDF (GBT38885-2020)

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GB/T 38885-2020: General specification for ultra-high cleanliness of high carbon chromium bearing steel

This standard specifies the order content, size, shape, weight, technical requirements, test methods, inspection rules, packaging, markings and quality certificates of ultra-high cleanliness of high-carbon chromium bearing steel. This standard is applicable to the hot-rolled or forged round steel, wire rod, cold-drawn round steel and steel wire which has a diameter of not more than 150 mm for the production of bearing rings and rolling elements with long contact fatigue life performance of automobiles, railways, energy sources, CNC machine tools.
GB/T 38885-2020
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 77.140.10
H 40
General specification for ultra-high cleanliness of high
carbon chromium bearing steel
ISSUED ON: JUNE 02, 2020
IMPLEMENTED ON: DECEMBER 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Order content ... 7
4 Dimensions, appearance, weight ... 7
5 Technical requirements ... 9
6 Test method ... 15
7 Inspection rules ... 17
8 Packaging, marking and quality certificate ... 20
General specification for ultra-high cleanliness of high
carbon chromium bearing steel
1 Scope
This standard specifies the order content, size, shape, weight, technical requirements, test methods, inspection rules, packaging, markings and quality certificates of ultra-high cleanliness of high-carbon chromium bearing steel. This standard is applicable to the hot-rolled or forged round steel, wire rod, cold- drawn round steel and steel wire which has a diameter of not more than 150 mm for the production of bearing rings and rolling elements with long contact fatigue life performance of automobiles, railways, energy sources, CNC
machine tools(hereinafter referred to as steel).
2 Normative references
The following documents are essential to the application of this document. For the dated documents, only the versions with the dates indicated are applicable to this document; for the undated documents, only the latest version (including all the amendments) are applicable to this standard.
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 223.23 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 -
round, square and hexagonal steels
GB/T 908-2019 Forged bars for dimensions, shape, weight and tolerances
GB/T 2101 General requirement of acceptance packaging marking and
certification for section steel
GB/T 2103 General requirements for acceptance, packing, marking and
quality certification of steel wire
GB/T 4162-2008 Forged and rolled steel bars - Method for ultrasonic 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 Metal - Methods for estimating the average grain size
GB/T 10561-2005 Steel - Determination of content of nonmetallic inclusions - Micrographic method using standards diagrams
GB/T 11261 Steel and iron - Determination of oxygen content - The pulse heating inert gas fusion-infra-red absorption method
GB/T 14981-2009 Dimension shape mass and tolerance for hot-rolled round wire rod
GB/T 18254-2016 High-carbon chromium bearing steel
GB/T 18579 High-carbon chromium bearing steel wires
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
GB/T 32548 Determination of iron, tin, antimony, cerium, lead and bismuth - Inductively coupled plasma - mass spectrometric method
GB/T 38683-2020 Method of ultrasonic testing for large inclusions in bearing steel
JB/T 10510 Test method for contact fatigue of rolling bearing material
5.14.4 The surface of the stripped, polished, machine-polished steel shall not have defects.
5.15 Contact fatigue life
The rated life L10 of the steel under the maximum contact stress of 4500 GPa shall not be less than 1 ?? 107 times.
6 Test method
6.1 Dimensions and appearance
Steel size measurement is carried out by a caliper or template that can ensure the necessary accuracy.
6.2 Chemical composition
6.2.1 The analysis method of chemical composition shall be carried out
according to the general methods such as GB/T 4336, GB/T 20123, GB/T
20125, GB/T 32548. For arbitration, it shall be according to the provisions of GB/T 223.5, GB/T 223.9, GB/T 223.11, 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 223.62, GB/T 223.63, GB/T 223.77, GB/T 223.85, GB/T 223.86.
6.2.2 The oxygen content specimen shall be tested after fully removing the decarburized layer. Its analysis method shall be carried out according to GB/T 11261.
6.2.3 The analysis method of titanium content shall be determined by the supplier and the buyer through negotiation.
6.3 Mechanical properties
The test method of Brinell hardness is in accordance with the provisions of GB/T 231.1. The tensile test method is in accordance with GB/T 228.1.
6.4 Macroscopic
The macroscopic acid leaching test method is carried out according to GB/T 226. The rating diagram is carried out according to Appendix A in GB/T 18254- 2016.
6.5 Macroscopic inclusions
Macroscopic inclusions shall be carried out according to the requirements of GB/T 38683-2020.
6.6 Microscopic inclusions
Specimens of non-metallic inclusions are quenched and tempered in
accordance with 6.15 and observed at a magnification of 100 times. The
evaluation method and rating diagram are performed in accordance with the method A in GB/T 10561-2005.
6.7 Decarburization layer
The measurement of the depth of the total decarburization layer is carried out in accordance with the metallographic method in GB/T 224-2019.
6.8 Microstructure
For microstructure testing, a transverse sample is taken. The polished surface is etched with a 2% nitric acid alcohol solution and observed at a magnification of 1000 times. It is rated according to the level 5 rating diagram in Appendix A of GB/T 18254-2016.
6.9 Carbide inhomogeneity
6.9.1 For the testing of carbide network, take transverse specimens; quench and temper it according to 6.15; use 4% nitric acid alcohol solution to etch it after polishing. The spheroidizing annealing steel is rated according to the level 6 rating diagram in Appendix A of GB/T 18254-2016 at a magnification of 500 times. The supplier can also evaluate the carbide network on the longitudinal specimen, but the transverse direction shall prevail.
6.9.2 For the testing of carbide strip, take longitudinal specimens. Quench and temper it according to 6.15 in the annealed state; use the 4% nitric acid alcohol solution to etch it after polishing. Make evaluation at the magnification of 100 times and 500 times. Follow the level 8 rating diagram in Appendix A of GB/T 18254-2016 to evaluate the degree, size and shape of carbide aggregation. 6.9.3 For the testing of carbide liquid precipitation, take the longitudinal specimen. Follow the requirements of 6.15 to perform quenching and tempering. After polishing, use the 4% nitric acid alcohol solution to etch it. Evaluate it according to the level 9 rating diagram in Appendix A of GB/T 18254-2016 at the magnification of 100 times.
6.10 Microscopic porosity
For the testing, take the longitudinal specimen for quenching and tempering according to 6.15. Evaluate it according to the level 10 rating diagram in Appendix A of GB/T 18254-2016 at the magnification of 100 times.
6.11 Grain size
right to conduct inspection and acceptance in accordance with the provisions of this standard.
7.2 Inspection classification
7.2.1 Type inspection
7.2.1.1 In one of the following situations, the manufacturer shall conduct type inspection:
a) Trial type identification of new product or the trans-plant production of old products;
b) After normal production, if there are major changes in materials, processes, and equipment that may affect product performance;
c) When the production is restored after suspension for more than 1 year; d) When there is a big difference between the exit-factory inspection result and the last type inspection result;
e) During normal production, inspection shall be carried out every 1 year; f) When the contract requires type inspection.
7.2.1.2 See Table 14 for type inspection items, sampling quantity and sampling locations.
7.2.1.3 When one of the inspection items is unqualified, the type inspection fails. 7.2.2 Exit-factory inspection
7.2.2.1 Group-batching rules
The steel shall be inspected and accepted by batch. Each batch shall be composed of steel with the same heat number, the same designation, the same size, the same delivery status, the same heat treatment furnace batch.
7.2.2.2 Sampling quantity and sampling location
7.2.2.2.1 See Table 14 for the sampling quantity and sampling location of each batch of steel.

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