GB/T 5068-2019 English PDF (GBT5068-2019)
GB/T 5068-2019 English PDF (GBT5068-2019)
GB/T 5068-2019: Axles steel for railway locomotive and wagons
NATIONAL STANDARD OF THE
PEOPLE REPUBLIC OF CHINA
Replacing GB/T 5068-1999
Axles steel for railway locomotive and wagons
ISSUED ON: JUNE 04, 2019
IMPLEMENTED ON: MAY 01, 2020
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Classification and code ... 7
4 Size, shape, weight, allowable deviation ... 7
5 Technical requirements ... 10
6 Test method ... 16
7 Inspection rules ... 17
8 Markings, quality certificates and packaging ... 18
Appendix A (Normative) Inspection sampling locations for mechanical
properties, non-metallic inclusions, chemical composition ... 20
Appendix B (Informative) Comparison of domestic and foreign designations 24 Axles steel for railway locomotive and wagons
This standard specifies the classification, code, size, shape, weight and allowable deviation, technical requirements, test methods, inspection rules, packaging, markings, quality certificates of axles steel for railway locomotive and wagons.
This standard is applicable to the high-quality carbon structural steel and alloy structural steel square steel and round steel (hereinafter referred to as axle billet) for the manufacture of axles for railway locomotive and wagons. 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) is applicable to this standard.
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 223.9 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 223.12 Methods for chemical analysis of iron, steel and alloy - The sodium carbonate separation-diphenyl carbazide photometric method for the determination of chromium content
GB/T 223.14 Methods for chemical analysis of iron, steel and alloy - The N- benzoyl-N-phenylhydroxylamine extraction photometric method for the
determination of vanadium content
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
determination of carbon content
GB/T 223.72 Iron, steel and alloy - Determination of sulfur content -
GB/T 223.74 Methods for chemical analysis of iron, steel and alloy - The combustion gravimetric/gas-volumetric method for the determination of
combined carbon content
GB/T 223.76 Methods for chemical analysis of iron, steel and alloy - The flame atomic absorption spectrometric method for the determination of
GB/T 226 Test method for macrostructure and defect of steel by etching
GB/T 228.1 Metallic materials - Tensile testing - Part 1: Method of test at room temperature
GB/T 229 Metallic materials - Charpy pendulum impact test method
GB/T 1979 Standard diagrams for macrostructure and defect of structural 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)
GB/T 6394 Metal - Methods for estimating the average grain size
GB/T 7736 Ultrasonic inspecting method for macro-structure and
imperfection of steel
GB/T 10561-2005 Steel - Determination of content of nonmetallic
inclusions - Micrographic method using standards diagrams
GB/T 11261 Steel and iron - Determination of oxygen content - The pulse heating inert gas fusion-infra-red absorption method
GB/T 17505 Steel and steel products - General technical delivery
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
3 Classification and code
Axle billets are classified into two types according to their uses: axle billets for railway locomotives and axle billets for wagons.
Code of axle billet for locomotive: JZ (JZ is the Chinese Pinyin prefix for the locomotive axle);
Code of the axle billet for wagon: LZ (LZ is the Chinese Pinyin prefix for the wagon axle).
4 Size, shape, weight, allowable deviation
4.1 Size and allowable deviation
4.1.1 The cross-section size and allowable deviation of square steel shall meet the requirements of Table 1.
4.1.2 The cross-section size and allowable deviation of round steel shall meet the requirements of Table 2.
4.1.3 The fixed-length or multiple-length of the axle billet shall be determined by the agreement between the supplier and the buyer and shall be indicated in the contract. The allowable deviation between fixed-length and multiple-length is 0 mm ~ 80 mm.
4.1.4 Forged steel shall be used for square steel with side length not less than 320 mm; rolled or forged steel shall be used for square steel with side length below 320 mm.
4.1.5 Axle billets of other specifications and deviations can be supplied upon agreement between the supplier and the buyer and indicated in the contract. 5.1.3 Upon agreement between the supplier and the buyer and indicated in the contract, axle billets of other designations and chemical compositions can be supplied.
5.2 Smelting and rolling, forging
5.2.1 The steel billets for the manufacture of axles shall be smelted in an electric arc furnace or a converter; meanwhile subjected to external refining and vacuum degassing treatment.
5.2.2 The billets after hot rolling or forging shall be stacked for cooling or put in pits for slow cooling and annealing.
5.2.3 The rolling ratio from ingot to axle billet shall not be less than 6:1; the forging ratio shall not be less than 3:1; the rolling ratio or forging ratio from continuous casting billet to axle billet shall not be less than 3:1. For LZ50, the rolling ratio or forging ratio of continuous casting billet to axle is not less than 3:1.
5.3 Delivery status
Axle billets are delivered in hot rolled or forged state. When the buyer has special needs, it shall be indicated in the contract.
There shall be no visible white spots, cracks, residual shrinkage holes, delamination, under-skin blisters, internal blisters, inclusions (non-metallic and dissimilar metals), peeling, intergranular cracks, bright strip, etc., on the horizontal acid-leached macrostructure test piece of the axle steel billet. The grade of acid-leached macrostructure shall meet the requirements of Table 5. Table 5 -- The grade of acid-leaching macrostructure
5.5 Non-metallic inclusions
The inspection of non-metallic inclusions in the axle billet shall be evaluated according to the method A in GB/T 10561-2005; the inspection results shall meet the requirements of Table 6.
Table 9 -- Mechanical properties
5.7 Grain size
5.7.1 Sampling position
The grain size specimen shall be taken from the undeformed large end of the tensile specimen or sampled at the position of the tensile specimen, as shown in Figure A.1 and Figure A.2, from the heat-treated sample billet.
5.7.2 Grain size of high-quality carbon structural steel
The specimen made of the undeformed large end or sample billet of the tensile sample after a normalizing heat treatment shall have a grain size grade of 5 or finer.
5.7.3 Grain size of alloy structural steel
According to the requirements of GB/T 6394, the austenite grain size of the axle billet shall be tested. The grain grade shall be 6 or finer, meanwhile the difference between the highest and the lowest grades shall not exceed 3. 5.8 Ultrasonic flaw detection
According to the requirements of the buyer, the axle billets for wagons can be ultrasonically tested after negotiation between the supplier and the buyer and indicated in the contract. Locomotive axle billets shall be tested by ultrasonic flaw detection one by one in case of exit-factory. Ultrasonic testing and evaluation shall be carried out according to GB/T 7736. For locomotive axle billet, the defect equivalent value is ??? ?? 3.2 mm; for wagon axle billet, the defect equivalent value shall be based on the requirements of the buyer. The quality certificate indicates that the flaw detection is qualified.
5.9 Surface quality
(if the heat treatment performance is unqualified, it is allowed to readjust the heat treatment once to inspect the mechanical properties; the billet is judged as qualified if the inspection is qualified). In addition, select two A-segment axle billets from the remaining batch of axle billets for the re-inspection of the unqualified item (white dots are not allowed to re-inspect). If the re-inspection result is qualified, the remaining axle billets of the batch are qualified. When one of the indicators in the re-inspection result (including any index required by the test of this item) is unqualified, all A-segment axle billets of the batch are judged as unqualified. In this case, samples can be taken from the non-marked end of any two A-segment billets or the marked end of the B-segment billet for the full item test. When one specimen fails, the batch of axle billets is judged as unqualified; when the test results are all qualified, all axle billets except the A- segment axle billets are qualified.
For continuous casting axle billets, if one of the test results does not meet the requirements of the technical conditions of this standard, this axle billet is scrapped (if the heat treatment performance is unqualified, it is allowed to readjust the heat treatment once to check the mechanical properties. After the inspection is qualified, the billet is judged to be qualified). Then sample the billets from the other two axle billets of the same batch for re-inspection of unqualified items (white dots are not allowed for re-inspection). One of the re- inspection billets shall be sampled from the axle billets rolled by the same casting billet, the other re-inspection sample billet shall be taken from the axle billets rolled by other casting billets. When the re-inspection results of the two re-inspection samples meet the requirements, the batch of axle billets shall be judged as qualified. Otherwise, the batch of axle billets shall be rejected. If the impact test results do not meet the requirements, 3 more specimens shall be taken from the same sampled product for testing. The average value of the 6 samples in succession shall not be less than the specified value in Table 5; two of the specimens are allowed to be below the specified value, but only one specimen is allowed to be less than 70% of the specified value.
Other requirements for re-inspection and determination of axle billets shall be implemented in accordance with GB/T 17505.
8 Markings, quality certificates and packaging
8.1.1 The end surface of the continuous casting axle steel shall be marked with the stream number (such as: 1, 2, ...), the piece number (indicated by 01, 02, ... starting from the first billet); the stream number and piece number are allowed to be compiled continuously (such as: 101, 102, ...). The end face of the die- casting axle steel that is equivalent to the head of the ingot near the cap mouth