GB/T 42785-2023Bearing steel wire rod (English PDF)

1 Scope

China's national standard for bearing steel wire rod. It specifies the terms and definitions, the order content and the technical requirements. This is the rod from which rolling elements are made - the balls and rollers of every bearing - drawn down, cut, formed and hardened. The requirements on it are the strictest applied to any high tonnage steel, and they concentrate on cleanness. A rolling element fails by subsurface fatigue initiated at a non-metallic inclusion at the depth of maximum shear stress, and the size of the largest inclusion in the volume that sees that stress determines the life. Since the volume is small and the number of elements is enormous, what matters statistically is not the average inclusion content but the extreme value - the largest inclusion likely to appear anywhere in a production lot. That is why bearing steel is made by vacuum degassing and why its acceptance uses extreme value methods rather than an average rating.

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

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

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;

d) Specification;

e) Weight (or quantity);

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.

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.

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.

9 Packaging, Marking and Quality Certificate

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Note 3. 10. **Verification (USD

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