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GB/T 33522-2017 English PDF (GBT33522-2017)

GB/T 33522-2017 English PDF (GBT33522-2017)

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GB/T 33522-2017: Carburizing bearing steel forgings -- Technical specification

This Standard specifies the ordering requirements, manufacturing process, technical requirements, inspection rules and test methods, acceptance and quality certificate, mark and package of carburizing bearing steel forgings. This Standard is applicable to the ordering, manufacturing and inspection of high quality carburizing bearing steel forgings used for manufacturing rolling bearing rings and rolling elements.
GB/T 33522-2017
GB
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 77.140.85
J 32
Carburizing Bearing Steel Forgings ?€?
Technical Specifications
ISSUED ON. FEBRUARY 28, 2017
IMPLEMENTED ON. SEPTEMBER 01, 2017
Issued by. General Administration of Quality Supervision, Inspection and Quarantine;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Ordering Requirements ... 5
4 Manufacturing Process ... 5
5 Technical Requirements ... 6
6 Inspection Rules and Test Methods ... 9
7 Acceptance and Quality Certificate ... 11
8 Mark and Package ... 11
Appendix A (Informative) Supplementary Technical Requirements ... 13
Carburizing Bearing Steel Forgings ?€?
Technical Specifications
1 Scope
This Standard specifies the ordering requirements, manufacturing process, technical requirements, inspection rules and test methods, acceptance and quality certificate, mark and package of carburizing bearing steel forgings.
This Standard is applicable to the ordering, manufacturing and inspection of high- quality carburizing bearing steel forgings used for manufacturing rolling bearing rings and rolling elements.
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 document.
GB/T 223 (all parts) Methods for Chemical Analysis of Iron, Steel and Alloy GB/T 224 Determination of Depth of Decarburization of Steels
GB/T 225 Steel - Hardenability Test by End Quenching (Jominy Test)
GB/T 226 Test Method for Macrostructure and Defect of Steel by Etching
GB/T 231.1 Metallic Materials ?€? Brinell Hardness Test ?€? Part 1. Test Method GB/T 908 Forged Round and Square Steels Dimension, Shape, Weight and
Tolerance
GB/T 1979 Standard Diagrams for Macrostructure and Defect of Structural Steels GB/T 6394 Metal ?€? Methods for Estimating the Average Grain Size
GB/T 6402 Steel Forgings ?€? Method for Ultrasonic Examination
GB/T 10561-2005 Steel - Determination of Content of Nonmetallic Inclusions - Micrographic Method Using Standards Diagrams
GB/T 20066 Steel and Iron-Sampling and Preparation of Samples for the
Determination of Chemical Composition
GB/T 21469 Machining Allowances and Tolerances for Steel Open Die Forgings on Hammer - General Requirement
GB/T 21470 Machining Allowances and Tolerances for Steel Open Die Forgings on Hammer - Disks Columns Rings and Seamless Cylindrical Sleeves
GB/T 21471 Machining Allowances and Tolerances for Steel Open Die Forgings on Hammer - Shafts
JB/T 9179 (all parts) Machining Allowances and Tolerances of Open Die Forgings on Hydraulic Press
3 Ordering Requirements
3.1 The purchaser shall specify the name, material grade, delivery status and supply quantity of the forgings in the ordering contract.
3.2 At the time of ordering, the purchaser (or supplier) shall provide the ordering drawings and related technical documents approved by both sides.
3.3 When the purchaser has supplementary requirements, it shall be specified in the contract.
3.4 The forgings are delivered in the normalized, tempered and annealed conditions; or delivered in the state agreed between the supplier and the purchaser. 4 Manufacturing Process
4.1 Smelting
The forgings shall adopt ladle refining or ladle refining and slag re-melting process. Other smelting methods that guarantee the quality can also be adopted.
4.2 Forging
4.2.1 The forgings shall be forged with steel ingots or rolled (forged) materials. Both ends of the steel ingot shall be remained enough length for cutting; so as to ensure the forgings have on shrinkage, looseness and severe compositional segregation. Forgings shall be forged in a forging equipment with adequate capabilities using The specimen for smelting analysis shall be sampled during casting period; it shall have the same furnace number with the steel ingot; the sampling and sample preparation methods shall be implemented as per the provisions of GB/T 20066. The electro-slag re-melting smelting analysis shall be based on the smelting analysis when the consumable electrode is prepared or the sampling method agreed by the supplier and the purchaser.
6.1.3 Analysis of the finished products
If the purchaser requires sampling and analyzing from the finished forgings, then the sampling and sample preparation method shall be implemented as per the provisions of GB/T 20066.
6.2 Hardness test
The hardness test method shall be implemented as per the provisions of GB/T 231.1; the test positions shall be agreed by the supplier and the purchaser.
6.3 Metallographic examination
6.3.1 Macrostructure inspection and non-metallic inclusion rating
6.3.1.1 The sampling quantities, sampling positions, specimen size for
macrostructure inspection and non-metallic inclusion rating shall be agreed by the supplier and the purchaser.
6.3.1.2 The macrostructure etching test shall be performed in the 1.1 hydrochloric acid aqueous solution at 60??C~80??C according to the provisions of GB/T 226; or perform electrolytic corrosion in 15%~20% (volume ratio) industrial hydrochloric acid aqueous solution at 30??C; the corrosion voltage is less than 20V; current intensity is 0.1A/cm2~1A/cm2; time is 15min~20min; the corrosions surface is parallel to the electrode; and the pole spacing is no less than 20mm. Macrostructure inspection shall be rated as per GB/T 1979.
6.3.1.3 The non-metallic inclusion rating shall adopt Method A to inspect and rate as per the provisions of GB/T 10561-2005. The specimen size is 20mm??20mm, cut at the position about 1/2 from the center to the surface of the forgings or forging test block. 6.3.2 Evaluation of grain size
6.3.2.1 The grain size evaluation shall be performed as per the comparison method in GB/T 6394 or agreed by the supplier and the purchaser.
6.3.2.2 For the forgings that don?€?t meet the requirements, they can be renormalized, re-tempered or re-annealed, and then evaluate; the number of reheating treatment shall not exceed twice.
Appendix A
(Informative)
Supplementary Technical Requirements
A.1 General
Only when specified in the contract, some or all of the following technical requirements apply. The adoption of technical requirements shall have the same effect as the text of this Standard. The details of the technical requirements are agreed by both sides; but the text of this Standard shall not be denied.
A.2 Residual elements
The purchaser can require the supplier to provide the analysis results for the chemical compositions of titanium, aluminum, oxygen and the like elements; then the sampling quantity and position shall be agreed by the supplier and the purchaser. A.3 ?€?SAM?€? inclusion rating system
A.3.1 In addition to rating of the non-metallic inclusions as specified in 6.3.1.3, the purchaser can designate to adopt ?€?SAM?€? inclusion rating system. This is a method to determine the purity of the bearing steel. In addition to evaluating the serious conditions, such rating system can also reflect the frequency of the occurrence of larger particle oxidized inclusions; the results shall be expressed by two rating grades reflecting the Type-B and Type-D inclusion contents.
A.3.2 The sampling shall be implemented as per the provisions of 6.3.1.1 and 6.3.1.3. A.3.3 The inclusion rating shall be performed as per 6.3.1.3 or agreed by the supplier and the purchaser.
A.4 Adding calcium
Without the special permission of the purchaser, the supplier can?€?t intentionally add calcium or alloys to deoxidize or control the inclusion morphology. Lime and/or fluorite are allowed during the slagging period.
A.5 Magnetic powder method
Except for the non-metallic inclusion rating method specified in 6.3.1.3, the purchaser can designate the magnetic powder method, which shall be agreed by the supplier and the purchaser.

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