GB/T 5068-2019 English PDF (GBT5068-2019)

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GB/T 5068-2019: Axles steel for railway locomotive and wagons
GB/T 5068-2019
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.60
H 43
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
1 Scope
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 -
Gravimetric method
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
vanadium content
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
requirements
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
3.1 Classification
Axle billets are classified into two types according to their uses: axle billets for
railway locomotives and axle billets for wagons.
3.2 Code
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.
5.4 Macrostructure
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...