GB/T 24242.1-2020 English PDF (GBT24242.1-2020)
GB/T 24242.1-2020 English PDF (GBT24242.1-2020)
GB/T 24242.1-2020: Non-alloy steel wire rod for conversion to wire -- Part 1: General requirements
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NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
Replacing GB/T 24242.1-2009
Non-alloy Steel Wire Rod for Conversion to Wire -
Part 1: General Requirements
(ISO 16120-1:2017, MOD)
ISSUED ON: SEPTEMBER 29, 2020
IMPLEMENTED ON: APRIL 1, 2021
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of
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Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative References ... 5
3 Dimensions, Shapes, Weights and Allowable Deviations ... 8
4 Order Content ... 8
5 Technical Requirements ... 8
6 Test Methods ... 10
7 Inspection Rules ... 11
8 Packaging, Marking and Quality Certificate ... 11
Appendix A (informative) A Comparison Table of Chapter No. between this Part and ISO 16120-1:2017 ... 13
Appendix B (informative) Technical Differences between this Part and ISO 16120-1:2017 and Causes for These Differences ... 15
Appendix C (normative) Determination of Reticulated Cementite of High Carbon Steel Wire Rod ... 18
Appendix D (normative) Measurement of Surface Defects ... 21
Appendix E (informative) Mechanical Damages ... 24
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Non-alloy Steel Wire Rod for Conversion to Wire - Part
1: General Requirements
This Part of GB/T 24242 specifies the dimensions, shapes, weights and allowable deviations, order content, technical requirements, test methods, inspection rules, packaging, marking and quality certificate of non-alloy steel wire rod for drawn or cold- rolled steel wire.
This Part is applicable to non-alloy hot-rolled steel wire rod for drawn or cold-rolled steel wire (hereinafter referred to as wire rod).
This Part is not applicable to the following parts:
---Free-cutting steel wire rod;
---Wire rod for cold heading and cold extrusion;
---Steel wire rod for welding;
---Wire rod for welded steel mesh for concrete;
---Ball and roller bearing steel;
---Wire rod for mechanical spring with a high fatigue strength, for example, wire rod for valve spring.
2 Normative References
The following documents are indispensable to the application of this document. In terms of references with a specified date, only versions with a specified date are applicable to this document. In terms of references without a specified date, the latest version (including all the modifications) is applicable to this document. GB/T 223.5 Steel and Iron - Determination of Acid-soluble Silicon and Total Silicon Content - Reduced Molybdosilicate Spectrophotometric Method (GB/T 223.5-2008, ISO 4829-1:1986, ISO 4829-2:1988, MOD)
GB/T 223.9 Iron Steel and Alloy - Determination of Aluminum Content - Chrome Azurol S Photometric 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 www.ChinesePart.net Buy True-PDF Auto-delivery. Page 7 of 29
for Section Steel
GB/T 2975 Steel and Steel Products - Location and Preparation of Samples and Test Pieces for Mechanical Testing (GB/T 2975-2018, ISO 377:2017, MOD)
GB/T 4336 Carbon and Low-alloy Steel - Determination of Multi-element Contents - Spark Discharge Atomic Emission Spectrometric Method (routine method)
GB/T 10561 Steel - Determination of Content of Nonmetallic Inclusions - Micrographic Method Using Standards Diagrams (GB/T 10561-2005, ISO 4967:1998, IDT)
GB/T 14981 Dimension, Shape, Mass and Tolerance for Hot-rolled Round Wire Rod (GB/T 14981-2009, ISO 16124:2004, MOD)
GB/T 20066 Steel and Iron - Sampling and Preparation of Samples for the Determination of Chemical Composition (GB/T 20066-2006, ISO 14284:1996, IDT) 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 20123-2006, ISO 15350:2000, IDT)
GB/T 20124 Crystalline Layered Sodium Disilicate (GB/T 20214-2006, ISO
GB/T 24242.2 Non-alloy Steel Wire Rod for Conversion to Wire - Part 2: Specific Requirements for General Purpose Wire Rod (GB/T 24242.2-2020, ISO 16120-2:2017, MOD)
GB/T 24242.3 Non-alloy Steel Wire Rod for Conversion to Wire - Part 3: Specific Requirements for Rimmed and Rimmed Substitute Low Carbon Steel Wire Rod (GB/T 24242.3-2014, ISO 16120-3:2011, MOD)
GB/T 24242.4 Non-alloy Steel Wire Rod for Conversion to Wire - Part 4: Specific Requirements for Special Purpose Wire Rod (GB/T 24242.4-2020, ISO 16120-4:2017, MOD)
YB/T 081 Rule for Rounding off of Numerical Values and Judgement of Testing Values for Technical Standards of Metallurgy
YB/T 169 Metallographic Test Method of Sorbite in High Carbon Steel Wire Rod YB/T 4411 Determination of Central Martensite in High Carbon Steel Wire Rod YB/T 4413 Metallographic Determination of Core Segregation in High Carbon Steel Wire Rod
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Steel shall be smelted by oxygen converter or electric arc furnace, and external refining if necessary.
5.3 Delivery State
Wire rod shall be delivered in the hot-rolled state.
5.4 Surface State
The surface of wire rod usually does not require any surface treatment; it shall be delivered in the natural surface state under the hot-rolled state. When the demand- side has demands, it may also be delivered with the surface state of removal of oxide scale.
5.5 Mechanical Properties
The mechanical properties of wire rod shall comply with the requirements of GB/T 24242.2, GB/T 24242.3 and GB/T 24242.4.
5.6 Decarburized Layer
The decarburized layer of wire rod shall comply with the requirements of GB/T 24242.2 and GB/T 24242.4.
5.7.1 Sorbite content
The sorbite content of wire rod shall comply with the requirements of GB/T 24242.2 and GB/T 24242.4.
5.7.2 Reticulated cementite
The reticulated cementite of wire rod shall comply with the requirements of GB/T 24242.2 and GB/T 24242.4.
5.7.3 Central martensite
The central martensite of wire rod shall comply with the requirements of GB/T 24242.2 and GB/T 24242.4.
5.8 Central Segregation
The central segregation of wire rod shall comply with the requirements of GB/T 24242.2 and GB/T 24242.4.
5.9 Non-metallic Inclusions
The non-metallic inclusions of wire rod shall comply with the requirements of GB/T www.ChinesePart.net Buy True-PDF Auto-delivery. Page 11 of 29
For the inspections of tensile test, decarburized layer, microstructure and non-metallic inclusions, the required specimens shall be cut from the end of wire rod with the head or tail already removed.
6.2 Chemical Analysis
The method of chemical analysis shall comply with GB/T 223.5, GB/T 223.9, GB/T 223.12, GB/T 223.19, GB/T 223.23, GB/T 223.26, GB/T 223.37, GB/T 223.50, GB/T 223.59, GB/T 223.62, GB/T 223.63, GB/T 223.68, GB/T 223.69, GB/T 223.74, GB/T 4336, GB/T 20123, GB/T 20124.
The arbitration shall comply with GB/T 223.5, GB/T 223.9, GB/T 223.12, GB/T 223.19, GB/T 223.23, GB/T 223.26, GB/T 223.37, GB/T 223.50, GB/T 223.59, GB/T 223.62, GB/T 223.63, GB/T 223.68, GB/T 223.69, GB/T223.74.
7 Inspection Rules
7.1 Inspection and Acceptance Inspection
The quality of wire rod shall be inspected by the supply-side’s quality supervision department. If necessary, the demand-side is entitled to conduct inspection and acceptance inspection in accordance with the stipulations of this Part. 7.2 Batch Rules
Wire rods shall be accepted in batches. Each batch shall be constituted of wire rods with the same heat number, the same designation, the same dimensions and the same rolling system.
The re-inspection and determination rules of wire rods shall comply with the stipulations of GB/T 2101.
7.4 Rounding-off of Test Result
The various inspection and measurement values of wire rod shall be rounded off in accordance with the rounding-off and comparison method. The rounding-off rule shall comply with the stipulations of YB/T 081.
8 Packaging, Marking and Quality Certificate
8.1 The packaging, marking and quality certificate of wire rod shall comply with the stipulations of GB/T 2101. Through the negotiation between the demand-side and the supply-side, and statement in the contract, other special requirements for packaging and protection may also be adopted.
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Determination of Reticulated Cementite of High Carbon Steel Wire Rod
This Appendix is applicable to wire rods made of non-alloy continuous cast steel with a carbon content greater than 0.65%.
In wire rods with strong segregation (carbon content greater than 0.8%) and a slow cooling rate, carbon segregates as secondary cementite at the grain boundary. In accordance with the segregation level and the cooling rate, cementite forms a more or less closed network along the grain boundary.
Use an appropriate etchant to conduct chemical etching on the polished cross-section of the wire rod, so as to reveal the reticulated cementite.
The surface to be inspected shall be the cross-section of the wire rod in the rolled state. C.3 Specimen Preparation and Etching
The specimen shall be prepared through metallography. Start with a section without mechanical deformation, and then, in accordance with the sequence, carry out appropriate grinding and polishing steps, so as to obtain a mirror-like and non- deformed surface.
After the final polishing (usually with diamond paste), use water to meticulously wash the specimen, then, use ethanol to clean it; finally, dry it.
The commonly used etchant is nitric acid ethanol etchant [100 mL of ethanol (ethyl alcohol) contains 2 mL of nitric acid ( = 1.33 g/mL)].
After the etching treatment, use water to meticulously wash the specimen again, then, use ethanol to clean it; finally, dry it.
After such etching, the matrix structure is merely slightly visible to the naked eye. The cementite existing at the grain boundary is clearly visible. See Figure C.1 for the schematic diagram of rating.
NOTE---in the toughened microstructure, a reticulated cementite might be in the form of spheroidization.
C.4 Inspection of Reticulated Cementite