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GB/T 18254-2016High-carbon chromium bearing steel (English PDF)

高碳铬轴承钢

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Issued by

General Administration of Quality Supervision, Inspection and Quarantine; Standardization Administration of the PRC

Level / Type

National · Recommended

Issue date

August 29, 2016

Implementation date

July 1, 2017

Scope

GB/T 18254-2016 is the English-translated version of 高碳铬轴承钢.

China's national standard for high-carbon chromium bearing steel - the steel from which rolling bearing rings and balls are made. It specifies the classification and codes, the ordering content, the dimensions, shape and weight, the technical requirements, the test methods, the inspection rules, and the packaging, marking and quality certification for high-carbon chromium bearing steel. Bearing steel is the most demanding commercial steel there is, and the reason is fatigue. A bearing raceway is loaded at a point contact where the Hertzian stress reaches several gigapascals, and that contact passes over every point of the raceway millions of times. The steel does not wear out; it fails by subsurface fatigue that initiates at an inclusion. So the property that determines bearing life is not strength or hardness - both are easily achieved - but cleanliness: the number, size, type and distribution of the non-metallic inclusions, and above all the oxide inclusions, which are hard, angular and act as crack starters. A single alumina inclusion of a few tens of micrometres in the wrong place ends the bearing. Almost everything distinctive about this standard follows from that. It sets composition limits including tight limits on oxygen and titanium, which control the oxide and nitride populations; it sets the macrostructure requirements against segregation and porosity; it sets the microstructure requirements on carbide network, carbide banding and carbide inhomogeneity, since undissolved carbides behave like inclusions; it sets decarburisation limits, the annealed hardness and the hardenability; and it fixes the non-metallic inclusion ratings by type with the methods for determining them. Normative annexes give the blue fracture test method and the assessment of carbide inhomogeneity and microporosity. Issued on 29 August 2016 and in force since 1 July 2017, it replaces GB/T 18254-2002.

Document preview — GB/T 18254-2016

National Standard of the People's Republic of China

ICS: 77.140.10
Classification: H 40
Replacing: GB/T 18254-2002

Issued by: General Administration of Quality Supervision, Inspection and Quarantine; Standardization Administration of the PRC

1 Application Scope
2 Normative References
3 Classification and Codes
4 Ordering Content
5 Dimensions, Shape and Weight
5.1 Dimensions and tolerances
5.1.2 Length
5.2 Shape and tolerances
6 Technical Requirements
6.1 Designation and chemical composition
6.4 Hardness
6.5 Forging
6.7 Fracture
6.7.1 Annealed fracture
7 Test Method
7.2 Chemical composition
7.6 Fracture
7.10 Inhomogeneity of carbide
8 Inspection Rules
8.1 Inspection and acceptance
8.3 Sampling quantity and sampling position
9 Packaging, Marking and Quality Certification

1 Application Scope

This Standard specifies the classification and codes, ordering content, dimensions, shape, technical requirements, test methods, inspection rules, packaging, marking and quality certification of high-carbon chromium bearing steels. This Standard applies to hot-rolled and forged round steels, round wire rods and cold- drawn round steels (bar or coil shape) of high-carbon chromium bearing steels for bearing rings and rollers (hereinafter referred to as steels). Steels or steel billets of other varieties or specifications can be supplied as agreed on by the supplier and the purchaser; the specific requirements shall be stated in the contract.

2 Normative References

The following referenced documents are indispensable for the application of this document. For dated references, only the edition dated applies to this document. For undated references, the latest edition of the referenced documents (including all amendments) applies 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 Aluminium Content - Chrom 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 - Distillation- molybdenum Blue Spectrophotometric Method

GB/T 223.47, Methods for Chemical Analysis of Iron, Steel and Alloy - The Carrier Precipitation-Molybdenum Blue Photometric Method for the Determination of Antimony Content

GB/T 223.50, Methods for Chemical Analysis of Iron, Steel and Alloy - The Phenylfuorone-CTMAB Direct Photometric Method for the Determination of Tin Content

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 223.62, Methods for Chemical Analysis of Iron, Steel and Alloy - The Butyl Acetate Extraction Photometric Method for the Determination of Phosphorus Content

GB/T 223.63, Methods for Chemical Analysis of Iron, Steel and Alloy - The Sodium (Potassium) Periodate Photometric Method for the Determination of Manganese Content

GB/T 223.77, Methods for Chemical Analysis of Iron, Steel and Alloy - The Flame Atomic Absorption Spectrometric Method for the Determination of Calcium Content

3 Classification and Codes

3.1 Steels are specified into the following in accordance with metallurgical quality.

a) quality steels;

b) high-grade quality steels (adding "A" after designation);

c) super-grade quality steels (adding "E" after designation).

3.2 Steels are classified into the following in accordance with casting process.

a) moulded steels;

b) continuously cast steels.

3.3 Steels are classified into the following in accordance with processing method for application.

a) steels for pressure processing, UP;

b) steels for machining, UC.

3.4 Steels are classified into the following in accordance with end use.

a) for rings, T;

b) for rollers, G;

4 Ordering Content

The contracts based on this Standard shall include the following content.

a) product name (description);

c) a reference to this Standard;

d) dimensions and accuracy;

e) weight and/or quantity;

f) casting method (continuous casting if not specified);

g) processing method for application

h) metallurgical quality;

i) delivery condition;

j) end use (for rings if not specified);

k) surface condition (when peeling, polishing or machining is required, it shall be specified);

l) items or indexes which shall be agreed on by the supplier and the purchaser and indicated in the contract;

m) other special requirements.

5.1 Dimensions and tolerances

5.1.1 Diameters of steels and their tolerances As specified in Table 1. Table 1 - Diameters of Steels and Their Tolerances Steel type Metallurgical quality Diameter and tolerance Hot-rolled round steels Quality steel and high-grade quality steels Group 2 in Table 1 in GB/T 702-2008 Super-grade quality steels Group 1 in Table 1 in GB/T 702-2008 Forged round steels - Group 1 in GB/T 908-2008 Cold-drawn round steels - Grade h11 in GB/T 905-1994a Round wire rod Quality steel and high-grade quality steels Accuracy grade B in GB/T 14981-2009 Super-grade quality steels Accuracy grade C in GB/T 14981-2009 a Steels of other grades can also be delivered as agreed on by the supplier and the purchaser and it shall be stated in the contract.

5.1.2 Length

5.1.2.1 Normal length of steels shall be as specified as follows:

a) 3 000 mm ~ 8 000 mm for hot-rolled round steels;

b) 2 000 mm ~ 6 000 mm for forged round steels;

c) 3 000 mm ~ 6 000 mm for cold-drawn round steels.

5.1.2.2 Steels shall be delivered in a specified length range; the difference between the maximum and minimum lengths in each bundle shall not be greater than 1 000 mm.

5.1.2.3 For steels to be delivered in specified length or double length, the deviations of their length shall not exceed.

5.2 Shape and tolerances

5.2.1 Out-of-roundness Out-of-roundness of steels shall be as specified in Table 2.

5.2.2 Bend Bend of steels shall be as specified in Table 3.

5.2.3 Torsion Steels shall be free from significant torsion.

6.1 Designation and chemical composition

6.1.1 Designation and chemical composition (by heat analysis) of steels shall be as specified in Table 4; their residual element content shall be as specified in Table 5.

6.1.2 Unless user's consent is obtained, the manufacturer shall not add calcium or its alloy for deoxidation or control of the morphology of non-metallic inclusions.

6.1.3 Tolerances for the chemical composition of finished steels (or steel billets) shall be as specified in Table 6.

6.1.4 Spark method for testing Steels shall be tested with the spark method or spectroscopic method. The test can be omitted if the supplier can guarantee this.

6.2 Smelting process Steels shall be treated by vacuum degassing.

6.3 Delivery condition Delivery condition of steels shall be as specified in Table 7.

6.4 Hardness

6.4.1 Brinell hardness of spheroidized annealed or softened annealed steels shall be as specified in Table 8.

6.4.2 Steels can be delivered in other hardness as required by the purchaser; the specific indexes shall be as agreed on by the supplier and the purchaser and stated in the contract.

6.5 Forging

6.5.1 Forging test shall be carried out for hot-rolled, forged, unannealed steels and cold-drawn round steels for upsetting and stamping. The side of test specimens shall be checked by visual inspection after forging, which shall be free from crack, tear, fold or bubble. The specific requirements are as follows:

a) hot forging test shall be carried out for hot-rolled forged steels with a diameter not greater than 60 mm;

b) cold forging test shall be carried out for cold-drawn round steels with a diameter not greater than 30 mm.

6.5.2 Forging test can be omitted if the supplier can guarantee this.

6.6 Macrostructure Etch macroscopic inspection shall be carried out for steels. The transverse etching test specimens shall be free from residual hole, crack, subsurface blowhole, overburnt, flakes and other harmful defects. The criteria for centre porosity, general porosity, pattern segregation and centre segregation shall be as specified in Table 9.

6.7.1 Annealed fracture

6.7.1.1 Annealed fracture inspection shall be carried out for hot-rolled spheroidized and softened annealed steels and cold-drawn round steels with a nominal diameter not greater than 30 mm. The annealed fracture shall show fine grain size, without shrinkage cavity, crack or overheating.

6.7.1.2 The inspection can be omitted if the supplier can guarantee that annealed fracture is as specified.

6.7.2 Bluing fracture Bluing fracture inspection shall be carried out for super-grade quality steel. The inspection results shall not be greater than

2.The maximum length of single strand shall not exceed 3 mm.

7 Test Method

7.1 Dimensions and shape Dimensional measurement of steels shall be carried out with calipers or templates which can guarantee necessary accuracy.

7.2 Chemical composition

7.3 Hardness The test method for Brinell hardness shall be as specified in GB/T 231.1.

7.4 Forging The method for forging test shall be as specified in YB/T 5293.

7.5 Macrostructure The microstructure etch test method shall be as specified in GB/T 226.The evaluation methods and standard diagrams shall be as specified in GB/T 1979 and the standard diagrams no. 1 ~ 4 in Annex A.

7.6 Fracture

7.6.1 The preparation of test specimens and method for annealed fracture and quenched fracture test shall be as specified in GB/T 1814.

7.6.2 The preparation of test specimens and test method for bluing fracture shall be as specified in Annex B.

7.7 Non-metallic inclusions Test specimens of non-metallic inclusions shall be observed after quenching and tempering as specified in

7.14 and magnification for 100 times. The evaluation methods and standard diagrams shall be as specified in method A in GB/T 20561-2005.

7.8 Decarburized layer Measurement of decarburized layer of the surface of steels shall be carried out in accordance with the metallographic method in GB/T 224-2008.

7.9 Microstructure Take transverse test specimens for the microstructure inspection. After using 2% nitric acid-alcoholic solution to etch polished surface, carry out observation by magnifying for 500 times and 1000 times (1 000 times during arbitration); evaluate them in accordance with standard diagram no. 5 in Annex A.

7.10 Inhomogeneity of carbide

7.10.1 Take transverse test specimens for carbide network inspection; carry out quenching and tempering treatment in accordance with 7.14; use 4% nitric acid- alcoholic solution for etching after polishing. Magnify for 500 times for spheroidized annealed steels and evaluate them in accordance with standard diagram no. 6 in Annex A; magnify for 200 times for hot-rolled (forged), softened annealed steels and evaluate them in accordance with standard diagram no. 7 in Annex A. The supplier can also evaluate carbide network on longitudinal test specimens, but the transverse shall prevail.

7.10.2 Take longitudinal test specimens for carbide band inspection; carry out quenching and tempering treatment in accordance with 7.14; use 4% nitric acid- alcoholic solution for etching after polishing. Magnify for 100 times and 500 times in combination; evaluate the aggregation degree, size and shape of carbide in accordance with standard diagram no. 8 in Annex A.

7.10.3 Take longitudinal test specimens for carbide liquation inspection; carry out quenching and tempering treatment in accordance with 7.14; use 4% nitric acid- alcoholic solution for etching after polishing; magnify for 100 times and evaluate them in accordance with standard diagram no. 9 in Annex A.

8.1 Inspection and acceptance

8.1.1 Ex-factory inspection shall be carried out by the quality and technology supervision department of the supplier for the quality of steels. The purchaser shall be entitled to carry out acceptance in accordance with the specifications of this Standard.

8.1.2 Inspection personnel can be dispatched to steel mill at any time as required by the user. Steel mill shall provide facilities for the work of the inspection personnel of the user in order to ensure steels to be delivered meet the requirements of this Standard. The inspection personnel of the user shall not disturb the production and operation of steel mill without reason.

8.2 Grouping rules Steels shall be inspected and accepted by batch. Each batch is composed of steels of the same furnace number, designation, size, delivery condition and heat treatment batch.

8.3 Sampling quantity and sampling position

8.3.1 Sampling quantity and sampling positions for all inspection items of each batch of steels shall be as specified in Table 18.

8.3.2 Sampling for chemical analysis shall be as specified in GB/T 20066.Oxygen content is tested on steel billets or steel materials. The sampling positions include. for steels with a diameter not less than 20 mm, one half of the radius of steels; for steels with a diameter less than 20 mm, the centre of steels.

8.3.3 Sampling positions for macrostructure, bluing fracture and quenched fracture shall be specified as follows:

a) moulded steels. the manufacturer shall take 1 test specimen from the head and tail of any steel ingot from the first, middle and last mould stool when casting each furnace of steels, 6 test specimens in total; if only two stools are cast in one furnace, take one steel ingot randomly from the first stool and take two steel ingots from the second stool, 3 test specimens in total, including one test specimen from the head and tail respectively; if only one mould steel is cast, take three steel ingots randomly, including one test specimen from the head and tail respectively. The test specimens shall be cut from the corresponding locations of rolled (forged) billets or materials before processing;

b) continuously cast steel. if the inspection is carried out on steels, then take one test specimen each from either end of any six pieces of steels.

9 Packaging, Marking and Quality Certification

9.1 Each bundle or each piece of steels shall be painted with colour strips or furnished with signs or labels on the end surface or 100 mm ~ 150 mm from the end, as specified in Table 21.

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 49 pages — is available in the English PDF.

Referenced standards

Normative references

GB/T 223.5 · GB/T 223.9 · GB/T 223.11 · GB/T 223.31 · GB/T 223.53 · GB/T 223.63 · GB/T 223.85 · GB/T 223.86 · GB/T 224-2008 · GB/T 905-1994 · GB/T 10561-2005 · GB/T 14981-2009 · GB/T 20066 · GB/T 20123 · GB/T 20125 · GB/T 5293

Cited by

Similar standards

GB/T 18254-2002|GB/T 10561-2005|GB/T 3203-2016|GB/T 34891-2017|GB/T 224-2008|GB/T 231.1-2018

Editions of GB/T 18254

Edition	Title	Revision	Status
GB/T 18254-2016	High-carbon chromium bearing steel	second revision	Current
GB/T 18254-2002	High-carbon chromium bearing steel	first revision	Superseded
GB/T 18254-2000	High-carbon chromium bearing steel	first issue	Superseded

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