GB/T 42670-2023 PDF in English
GB/T 42670-2023 (GB/T42670-2023, GBT 42670-2023, GBT42670-2023)
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Test method for Rockwell hardness of carbon materials
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GB/T 42670-2023: PDF in English (GBT 42670-2023) GB/T 42670-2023
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 29.050
CCS Q 52
Test Method for Rockwell Hardness of Carbon Materials
ISSUED ON: AUGUST 6, 2023
IMPLEMENTED ON: MARCH 1, 2024
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Terms and Definitions ... 4
4 Principle ... 5
5 Instrument and Equipment ... 6
6 Specimens ... 6
7 Test Procedures ... 7
8 Precision ... 7
9 Test Report ... 8
Appendix A (informative) Rockwell Scale ... 9
Bibliography ... 10
Foreword
This document was drafted in accordance with the rules provided in GB/T 1.1-2020 Directives
for Standardization - Part 1: Rules for the Structure and Drafting of Standardizing Documents.
Please be noted that certain content of this document may involve patents. The institution
issuing this document does not undertake the responsibility of identifying these patents.
This document was proposed by China Iron & Steel Association.
This document shall be under the jurisdiction of National Technical Committee on Steel of
Standardization Administration of China (SAC/TC 183).
The drafting organizations of this document: SINOSTEEL New Materials Co., Ltd.; Shanghai
Research Institute of Materials Co., Ltd.; China Metallurgical Information and Standardization
Institute.
The main drafters of this document: Yang Hui, Xu Jianping, Wang Xiaoyuan, Mao Yuzhen,
Wang Wendong, Wu Jie, Wang Fei, Wang Yanlong, Zhou Wenyu, Xu Hanchun.
Test Method for Rockwell Hardness of Carbon Materials
1 Scope
This document describes the principle, instrument and equipment, specimens, test procedures,
precision and test report of the test method for Rockwell hardness of carbon materials.
This document is applicable to the determination of Rockwell hardness of carbon materials with
aggregate particles less than 0.8 mm. Other carbon materials may take this as a reference.
2 Normative References
The contents of the following documents constitute indispensable clauses of this document
through the normative references in the text. 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 230.2 Metallic Materials - Rockwell Hardness Test - Part 2: Verification and Calibration
of Testing Machines and Indenters
GB/T 1427 Sample Method of Carbon Material
GB/T 8170 Rules of Rounding off for Numerical Values & Expression and Judgement of
Limiting Values
JJG 112 Metallic Rockwell Hardness Testing Machines (Scales A, B, C, D, E, F, G, H, K, N, T)
JJG 884 Plastic Rock Well Hardness Testing Machine
3 Terms and Definitions
The following terms and definitions are applicable to this document.
3.1 Rockwell hardness
HR
A method of testing and expressing the hardness of a material.
3.2 Rockwell scale
Different combinations that are formed in accordance with the indenter and test force used.
NOTE: usually Rockwell scale has A, B, C, H, K, L, etc., for example, 80HRL means that the
Rockwell hardness tested with L scale is 80HR.
requirements.
6.2.2 The parallelism deviation of the specimens shall not be greater than 0.10 mm/100 mm.
6.2.3 Under the conditions allowed by the material, the roughness of both end surfaces of the
processed specimen Ra 3.2 m.
6.2.4 The surface of the processed specimen shall be free of visible cracks, edge-off, unfilled
corners, bulges, pits, holes and other defects.
7 Test Procedures
7.1 Test Preparation
7.1.1 Level the equipment and check the workbench to make sure it is free of dust and dirt.
Check the indenter to make sure it is not rusty or scratched.
7.1.2 In accordance with the stipulations of GB/T 230.2, JJG 112 or JJG 884, calibrate the
equipment.
7.2 Test Process
7.2.1 Place the specimen on the specimen placing table of the equipment, keep it stable, and
adjust the operating panel of lifting, so that the indenter contacts the surface of the specimen to
be tested.
7.2.2 Continue to slowly adjust the operating panel of lifting, until the equipment indenter starts
to load the initial test force on the specimen. The initial test force loading time is less than 2 s,
then, load the main test force. The main test force loading time is 1 s ~ 8 s, and the total test
force holding time is 2 s ~ 6 s, finally, release the main test force and maintain the initial test
force. After the test is completed, read and record the value.
7.2.3 Unload the initial test force, adjust the operating panel of lifting, and adjust the position
of the specimen to other points to be tested. Repeat 7.2.1 and 7.2.2. Each specimen is tested at
least 5 times at different positions on the surface to be tested and take the average value. The
distance between the centers of two adjacent indentations or the distance from the center of the
indentation to the edge of the specimen shall be greater than the diameter of the Rockwell scale
indenter, and the test shall be conducted on the same surface of the specimen.
7.2.4 The results shall retain one decimal place. The rounding-off of the numerical values shall
be carried out in accordance with the stipulations of GB/T 8170.
8 Precision
The deviation of parallel test is not greater than 3 HRL (Scale L). The precision of other scales
shall take the stipulations of GB/T 230.1 as a reference.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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