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GB/T 3086-2019 English PDF (GBT3086-2019)

GB/T 3086-2019 English PDF (GBT3086-2019)

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GB/T 3086-2019: High carbon chromium stainless bearing steels

This Standard specifies the order content, dimensions, shape, weight, technical requirements, test methods, inspection rules, packaging, marking, and quality certification of high carbon chromium stainless bearing steels. This Standard applies to hot-rolled (forged), cold-drawn, peeled, and polished round steels with a nominal diameter of 5 mm~160 mm, round wire rods with a nominal diameter of 5 mm~40 mm, and round steel wires with a nominal diameter of 1 mm~16 mm.
GB/T 3086-2019
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
ICS 77.140.20
H 40
Replacing GB/T 3086-2008
High carbon chromium stainless bearing steels
ISSUED ON: JUNE 04, 2019
IMPLEMENTED ON: MAY 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of the PRC.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Classification ... 7
4 Order content ... 8
5 Dimensions, shape, weight ... 8
6 Technical requirements ... 10
7 Test methods ... 14
8 Inspection rules ... 16
9 Packaging, marking, and quality certification ... 16
Appendix A (Informative) Comparison of this Standard?€?s designations with foreign standards?€? designations ... 17
Appendix B (Normative) Standard diagrams of micropore and twin-crystal
carbide structure ... 18
Foreword
This Standard is drafted in accordance with the rules given in GB/T 1.1-2009. This Standard replaces GB/T 3086-2008 ?€?High carbon chromium stainless
bearing steels?€?. Compared with GB/T 3086-2008, the main technical changes of this Standard are as follows:
- ADD the classification according to steel?€?s end use (see 3.2);
- Specify the tolerances for steel wire?€?s diameter (see 5.1.2);
- Tighten requirements for sulfur and nickel content of chemical composition (see Table 4; Table 3 of the 2008 edition);
- Delete the smelting method of induction furnace (6.2 of the 2008 edition); - Delete the inspection requirements for upsetting and fracture (6.5 and 6.6.2 of the 2008 edition);
- Modify the macrostructure evaluation standards and requirements (see
6.5.1; 6.6.1 of the 2008 edition);
- Delete the provision that if the supplier can ensure the tower inspection is qualified, the tower inspection may be omitted (see 6.6.3 of the 2008
edition);
- Modify the rating diagrams and methods for non-metallic inclusions and the qualification level of DS-type inclusions (see Table 8; Table 6 and Appendix B of the 2008 edition);
- Modify the evaluation method of eutectic carbide and add the evaluation and requirements for eutectic carbide size (see 6.7; 6.8 of the 2008 edition); - Modify the requirements for depth of decarburization of steels (see 6.10; 6.11 of the 2008 edition);
- ADD requirement for non-destructive testing (see 6.11);
- Modify the lot grouping rules (see 8.2; 8.2 of the 2008 edition);
- Modify the re-inspection and decision rules (see 8.4; 8.4 of the 2008 edition); - ADD a table for comparison of this Standard?€?s designations with foreign standards?€? similar designations (see Appendix A);
- Delete standard rating diagrams of macrostructure and non-metallic
High carbon chromium stainless bearing steels
1 Scope
This Standard specifies the order content, dimensions, shape, weight, technical requirements, test methods, inspection rules, packaging, marking, and quality certification of high carbon chromium stainless bearing steels.
This Standard applies to hot-rolled (forged), cold-drawn, peeled, and polished round steels with a nominal diameter of 5 mm~160 mm, round wire rods with a nominal diameter of 5 mm~40 mm, and round steel wires with a nominal
diameter of 1 mm~16 mm (hereinafter referred to as ?€?steels?€?).
2 Normative references
The following documents are indispensable for the application of this document. For the dated references, only the editions with the dates indicated are applicable to this document. For the undated references, the latest edition (including all the amendments) are applicable to this document.
GB/T 222 Permissible Tolerances for Chemical Composition of Steel
Products
GB/T 223.5 Steel and iron - Determination of acid-soluble silicon and total silicon content - Reduced molybdosilicate spectrophotometric method
GB/T 223.11 Iron, steel and alloy - Determination of chromium content - Visual titration or potentiometric titration method
GB/T 223.18 Methods for Chemical Analysis of Iron, Steel and Alloy - The Sodium Thiosulfate Separation Iodimetric Method for the Determination of Copper 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 223.62 Methods for chemical analysis of iron, steel and alloy - The butyl acetate extraction photometric method for the determination of
phosphorus content
- Micrographic Method Using Standards Diagrams
GB/T 11170 Stainless steel - Determination of multi-element contents - Spark discharge atomic emission spectrometric method (Routine method)
GB/T 13298 Inspection methods of microstructure for metals
GB/T 14979-1994 Eutectic carbide of steel - Micrographic method using
Standard diagrams
GB/T 14981-2009 Dimension shape mass and tolerance for hot-rolled round wire rod
GB/T 15711 Inspection of non-metallic inclusions of steel - Etching test method of tower sample
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
GJB 9443 Test method for macroetch testing of remelted steel bars and
billets
3 Classification
3.1 Steel, according to the processing method used, is divided into the following two categories. The processing method used for steel shall be indicated in the contract. If not indicated, it shall be supplied according to the steel for cut work. a) Steel for pressure work - UP;
b) Steel for cut work - UC.
3.2 Steel, according to the end use, is divided into the following two categories. The end use of steel shall be indicated in the contract. If not indicated, it shall be supplied according to the steel for ferrule.
a) G for rolling elements:
1) GQ for steel balls;
Table 9 -- Depth of decarburization of steel
In millimeters
Nominal diameter Depth of total decarburization No more than
???10 0.10
>10~160 1% of nominal diameter
>160 Agreed between the parties
6.11 Non-destructive testing
6.11.1 Round steels shall be subjected to ultrasonic testing. For those with a nominal diameter of not more than 60 mm, it shall meet Grade AA of GB/T 4162- 2008. For those with a nominal diameter of 60 mm~120 mm, it shall meet Grade A of GB/T 4162-2008. For those with a nominal diameter of more than 120 mm, the qualification level is negotiated by both the supplier and the purchaser. 6.11.2 Round steels shall be subjected to surface flaw detection using
appropriate methods. The specific method is selected by the supplier.
6.12 Surface quality
6.12.1 The surface of hot-rolled (forged) round steels shall be free of cracks, folds, pull cracks, scarring, inclusions, and other defects harmful to use and shall meet the following requirements:
a) The removal depth of harmful defects on the surface of steel for pressure work is calculated from the actual size. For the round steel with a nominal diameter of not more than 80 mm, it shall not exceed half of the
dimensional tolerance. For the round steel with a nominal diameter
greater than 80 mm, it shall not exceed the dimensional tolerance;
b) The removal depth of harmful defects on the surface of steel for cut work is calculated from the nominal size. For the round steel with a nominal diameter of not more than 80 mm, it shall not exceed half of the
dimensional tolerance. For the round steel with a nominal diameter
greater than 80 mm, it shall not exceed the dimensional tolerance.
6.12.2 The surface of hot-rolled round wire rods shall be smooth and shall be free of cracks, folds, ears, scarring, delamination, and inclusions. Indentations and local bumps, scratches, pitting are allowed. Their depth or height
(calculated from actual size) shall comply with Table 10.
8 Inspection rules
8.1 Inspection and acceptance
The inspection and acceptance of steels shall be carried out by the supplier?€?s technical quality supervision department. The purchaser has the right to accept in accordance with the provisions of this Standard.
8.2 Lot grouping rules
Steels shall, in lots, be submitted for inspection and acceptance. Each lot shall consist of steels of the same designation, same sub-furnace number, same processing method, same dimension, same delivery state, and same heat
treatment heat.
8.3 Sampling locations and sampling quantities
The sampling locations and sampling quantities of each lot of steels shall comply with the requirements of Table 12.
8.4 Re-inspection and decision rules
8.4.1 If any item of the inspection items is unqualified (except for white spots and non-metallic inclusions), the same quantity of samples may be taken again to re-inspect the unqualified items. If the re-inspection result is still unqualified, this lot of steels is judged as unqualified.
8.4.2 If the inspection of dimensions, shape, and surface quality of steels is unqualified, it shall be judged as unqualified according to pieces (coils). For steels which fail to pass the inspection of dimensions, shape, and surface quality, it is allowed to re-repair, straighten, or grind piece by piece (coil by coil) for re-inspection. The qualified ones are delivered.
8.4.3 If the supplier can ensure the macrostructure, non-metallic inclusions, and heterogeneity of eutectic carbide of steels are qualified, it is allowed to replace the material with billet and replace small piece with large piece.
9 Packaging, marking, and quality certification
9.1 The packaging, marking, and quality certification of round steels and wire rods shall comply with the provisions of GB/T 2101.
9.2 The packaging, marking, and quality certification of steel wires shall comply with the provisions of GB/T 2103.

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