GB/T Translated English of Chinese Standard: GB/T NATIONAL STANDARD OF THE

Transcription

1 Translated English of Chinese Standard: GB/T GB NATIONAL STANDARD OF THE PEOPLE S REPUBLIC OF CHINA ICS H 40 GB/T Replacing GB/T High-carbon Chromium Bearing Steels 高碳铬轴承钢 Issued on: August 29, 2016 Implemented on: July 1, 2017 Issued by: General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China; Standardization Administration of the People's Republic of China. Page 1 of 51

2 Table of Contents Foreword Application Scope Normative References Classification and Codes Ordering Content Dimensions, Shape and Weight Technical Requirements Test Method Inspection Rules Packaging, Marking and Quality Certification Annex A (Normative) Standard Diagrams of High-carbon Chromium Bearing Steels Annex B (Normative) Test Method for Bluing Fracture Annex C (Normative) Sampling Diagrams for Microstructure, Carbide Inhomogeneity and Microporosity Page 2 of 51

3 Foreword This Standard was drafted in accordance with the rules given in GB/T This Standard replaces GB/T , High-carbon Chromium Bearing Steel. Compared with GB/T , the main changes of the technical content of this Standard are as follows: -- it cancels the varieties of steel tubes (see 1, , 5.1.3, , , and of edition 2002); -- it adds classification and codes (see Article 3); -- it adds end use and surface condition in ordering content (see Article 4; Article 3 of edition 2002); -- steels are classified into three quality grades, i.e. quality steels, high-grade quality steels and super-grade quality steels, in accordance with the metallurgical quality (see Table 1, 2, 5, 9, 10, 14, 15, 16; 4.1.1, , 4.2.1, Table 3, 6, 7, 5.8, Table 8 and 9 of edition 2002); -- it changes the upper limits of delivery lengths of hot-rolled round steels and forged round steels (see ; of edition 2002); -- it changes the coil weight of wire rod (see 5.3; of edition 2002); -- it tightens the bend indexes of hot-rolled round steels (see Table 3; Table 2 of edition 2002); -- it cancels designation GCr4 and its relevant technical requirements (see Table 3, 5, 12 of edition 2002); -- it cancels the specification of Ni + Cu 0.50% (see Table 3 of edition 2002); -- it adds designation G8Cr15 and its relevant technical requirements (see Table 4, 8, 6.8, Table 21); -- it tightens the content indexes of nickel, phosphorus, Sulphur and oxygen (see Table 4, 5; Table 3 of edition 2002); -- it adds the assessment indexes of aluminum, titanium, calcium, arsenic, antimony and lead (see Table 5; of edition 2002); -- it changes the hardness of softened annealed steels (see Table 8; Table 5 of edition 2002); -- it adds the test items and standard diagrams of centre segregation (Table 9 and standard diagram 4 of Annex A; Table 6 of edition 2002); Page 3 of 51

4 High-carbon Chromium Bearing Steels 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 colddrawn 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 , Iron, Steel and Alloy Determination of Chromium Content Visual Titration or Potentiometric Titration Method GB/T , Iron, Steel and Alloy Determination of Nickel Content The Dimethylglyoxime Spectrophotometric Method GB/T , Iron, Steel and Alloy Determination of Molybdenum Content The Thiocyanate Spectrophotometric Method GB/T , Iron, Steel and Alloy Determination of Lead Content Carrier Precipitation-Xylenol Orange Spectrophotometric Method GB/T , Iron, Steel and Alloy Determination of Arsenic Content Distillationmolybdenum Blue Spectrophotometric Method GB/T , Methods for Chemical Analysis of Iron, Steel and Alloy The Carrier Precipitation-Molybdenum Blue Photometric Method for the Determination of Page 6 of 51

5 Antimony Content GB/T , Methods for Chemical Analysis of Iron, Steel and Alloy The Phenylfuorone-CTMAB Direct Photometric Method for the Determination of Tin Content GB/T , Methods for Chemical Analysis of Iron, Steel and Alloy The Flame Atomic Absorption Spectrophotometric Method for the Determination of Copper Content GB/T , Methods for Chemical Analysis of Iron, Steel and Alloy The Butyl Acetate Extraction Photometric Method for the Determination of Phosphorus Content GB/T , Methods for Chemical Analysis of Iron, Steel and Alloy The Sodium (Potassium) Periodate Photometric Method for the Determination of Manganese Content GB/T , Methods for Chemical Analysis of Iron, Steel and Alloy The Flame Atomic Absorption Spectrometric Method for the Determination of Calcium Content GB/T , Iron, Steel and Alloy Determination of Sulfur Content Infrared Absorption Method after Combustion in an Induction Furnace GB/T , Iron, Steel and Alloy Determination of Total Carbon Content Infrared Absorption Method after Combustion in an Induction Furnace GB/T , Determination of Depth of Decarburization of Steels 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 , Hot-rolled Steel Bars Dimensions, Shape, Weight and Tolerances GB/T , Dimension, Shape, Weight and Tolerance for Cold-Drawn Round, Square and Hexagonal Steels GB/T , Forged Bars - Dimensions, Shape, Weight and Tolerances GB/T 1814, Inspection Method for Steel Work Fractures GB/T 1979, Standard Diagrams for Macrostructure and Defect of Structure Steels GB/T 2101, General Requirement of Acceptance, Packaging, Marking and Certification for Section Steel GB/T 4336, Carbon and Low-Alloy Steel Determination of Multi-Element Contents Spark Discharge Atomic Emission Spectrometric Method (Routine Method) Page 7 of 51

6 GB/T , Steel Determination of Content of Nonmetallic Inclusions Micrographic Method Using Standard Diagrams GB/T 11261, Steel and Iron Determination of Oxygen Content The Pulse Heating Inert Gas Fusion-Infra-Red Absorption Method GB/T , Dimension, Shape, Mass and Tolerance for Hot-rolled Round Wire Rod 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 5293, Metallic Materials - Forging Test 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; Page 8 of 51

7 Table 3 Bend of Steels Steel type Bend per meter dimensions in millimeters Bend not greater than Total bend Hot-rolled round steels % steels length Hot-rolled annealed round steels % steels length Cold-drawn round steels Forged round steels % steels length Diameter % steels length Diameter > % steels length Bend of steels can also be delivered in accordance with other specifications, which shall be agreed on by the supplier and the purchaser and stated in the contract Torsion Steels shall be free from significant torsion End shape Steels shall be cut or sheared neatly at the end, without overlap, burr and bias cutting or flattening which is adverse to use Gas cutting is usually not permitted for steels. Under exceptional circumstances (mainly referring to sampling), gas cutting at one end of not more than 6 pcs of steels in each batch is permitted One end of super-grade quality steels shall be chamfered. If quality steels and super-grade quality steels are to be chamfered, it shall be stated in the contract. 5.3 Weight Steels shall be delivered in actual weight. Coil weight of round wire rods shall be as specified in GB/T Technical Requirements 6.1 Designation and chemical composition 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 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. Page 11 of 51

8 supplier and the purchaser The analysis of designation and composition shall be with the spark method or spectroscopic method. 7.3 Hardness The test method for Brinell hardness shall be as specified in GB/T Forging The method for forging test shall be as specified in YB/T 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 The preparation of test specimens and method for annealed fracture and quenched fracture test shall be as specified in GB/T 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 Decarburized layer Measurement of decarburized layer of the surface of steels shall be carried out in accordance with the metallographic method in GB/T 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 Inhomogeneity of carbide Take transverse test specimens for carbide network inspection; carry out quenching and tempering treatment in accordance with 7.14; use 4% nitric acidalcoholic solution for etching after polishing. Magnify for 500 times for spheroidized Page 20 of 51

9 e) tempering time: 1 h ~ 2 h Rating principles The most adverse view field and area on the test surface of test specimens are used as the rating basis for all inspection items. 8 Inspection Rules 8.1 Inspection and acceptance 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 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 Sampling quantity and sampling positions for all inspection items of each batch of steels shall be as specified in Table Sampling for chemical analysis shall be as specified in GB/T 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 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 Page 22 of 51

10 Annex B (Normative) Test Method for Bluing Fracture B.1 Scope The test method for bluing fracture specified in this Annex applies to forged or rolled products as well as other products. This test method is generally used on semi-finished products; test specimens are cut from the corrsponding positions of (forged) billets (materials) with a diameter or side length 80 mm ~ 120 mm. B.2 Prindiple Fracture surface treated by bluing annealing shows total amount and distribution of visible non-metallic inclusions. Bluing fracture is on the longitudinal direction of products; inclusions usually appear white strips. B.3 Sampling and preparation B.3.1 Sampling Test specimens are cut by hot sawing or flame cutting. Test specimens are sheets; their depth are subjected to the dimensions of products (e.g. between 5 mm ~ 20 mm). The thickness 10 mm is generally recommended. The thickness of test specimens is parallel to longitudinal measurement. NOTE During flame cutting, it should be ensured that fracture is outside heat affected zone. B.3.2 Preparation Make a slot in the middle of the thickness of test specimens; the shape of slot is indefinite; the thickness of remaining sheet meet the specifications above. B.3.3 Test method B After normalizing treatment, test specimens can be treated as follows, if necessary: a) heating in the air to make metal at blue brittleness temperature at the beginning of test (300 C ~ 350 C); b) heating two specimens to make fracture blue after breaking them under normal temperature. B As agreed on by the interested parties, test specimens can be quenched and tempered immediately after quenching, under certain circumstances. Page 43 of 51