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GB/T 231.2-2022 English PDF (GBT231.2-2022)

GB/T 231.2-2022 English PDF (GBT231.2-2022)

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GB/T 231.2-2022: Metallic materials - Brinell hardness test - Part 2: Verification and calibration of testing machines

GB/T 231.2-2022
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 19.060;77.040.10
CCS N 71
Replacing GB/T 231.2-2012
Metallic materials - Brinell hardness test - Part 2:
Verification and calibration of testing machines
(ISO 6506-2:2017, MOD)
ISSUED ON: JULY 11, 2022
IMPLEMENTED ON: FEBRUARY 01, 2023
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
Introduction ... 6
1 Scope ... 7
2 Normative references ... 7
3 Terms and definitions ... 8
4 General requirements ... 8
5 Direct verification ... 8
5.1 General ... 8
5.2 Measurement of the test forces ... 9
5.3 Measurement of the properties of the indenter ball ... 9
5.4 Calibration of the indentation diameter measuring system ... 10
5.5 Verification of the testing cycle ... 11
6 Indirect verification ... 11
7 Intervals between verifications ... 13
8 Verification report/calibration certificate ... 14
Annex A (Informative) Uncertainty of measurement of the verification results of the hardness testing machine ... 15
Annex B (Normative) Verification of hardness testing machines that are incapable of meeting the specified force/time profile ... 23
References ... 24
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.
This document is Part 2 of GB/T 231 Metallic materials - Brinell hardness test. The following parts have been released for GB/T 231:
-- Part 1: Test method;
-- Part 2: Verification and calibration of testing machines;
-- Part 3: Calibration of reference blocks;
-- Part 4: Tables of hardness values.
This document replaces GB/T 231.2-2012 Metallic materials - Brinell hardness test - Part 2: Verification and calibration of testing machines; compared with GB/T 231.2- 2012, the major technical changes are as follows:
-- According to the force-diameter indices, MODIFY the hardness ranges of low, medium and high reference blocks used for indirect verification of hardness testing machine, and the relative repeatability of the hardness testing machine corresponding to different hardness ranges of the tested hardness testing machine, as well as the permissible error (see 6.7 and 6.9; 5.7 and 5.8 of the 2012 edition); -- ADD Annex B “Verification of hardness testing machines that are incapable of meeting the specified force/time profile” (see Annex B).
This document adopts the modification of ISO 6506-2:2017 Metallic materials - Brinell hardness test - Part 2: Verification and calibration of testing machines. Compared with ISO 6506-2:2017, this document is adjusted, in structure, as follows: -- CHANGE 5.3.4.1 and 5.3.4.2 in ISO 6506-2:2017 to 5.3.5 and 5.3.6.
There are technical differences between this document and ISO 6506-2:2017, and the clauses involved in these differences have been marked by a vertical single line (|) in the outer margin of the document. The specific technical differences and their reasons are as follows:
-- REPLACE ISO 6506-1 WITH GB/T 231.1, which adopts the international
standard by modification, (see Clause 1, 5.2.4, 5.5.2, 6.4, A.1 and Annex B), to adapt to the technical conditions in China;
-- REPLACE ISO 6506-3 WITH GB/T 231.3, which adopts the international
standard by modification, (see Clause 1, 5.4.3, 6.1), to adapt to the technical conditions in China;
-- ADD reference to GB/T 36416.1-2018 (see Clause 3);
-- REPLACE ISO 6507-1 (see 5.3.4.2) WITH GB/T 4340.1, which adopts the
international standard by modification, to adapt to the technical conditions in China.
This document makes the following editorial changes:
-- MODIFY the numbers “1”, “2” and “3” used to indicate “Hardness range of the hardness testing machine” in the first column of Table 2 and Table 3 to Chinese characters “low”, “medium” and “high”, respectively (see 6.7);
-- MODIFY the symbol “×” used to indicate “required inspection items” in Table 4 to the symbol “√”, and ADD the symbol “-” to indicate “non-inspected items” (see Clause 7);
-- NUMBER the unnumbered formulas in Annex A of ISO 6506-2:2017 in sequence (see Annex A);
-- CHANGE the symbol “𝑏ത ” in Formula (A.6), Formula (A.8) and Table A.9 in Annex A of ISO 6506-2:2017 to the symbol “E” [see Formula (A.10), Formula (A.13) and Table A.9].
Please note that some of the contents of this document may involve patents. The issuing organization of this document is not responsible for identifying patents. This document was proposed by China Mechinery Industry Federation.
This document shall be under the jurisdiction of National Technical Committee 122 on Testing Machines of Standardization Administration of China (SAC/TC 122). Drafting organizations of this document: Kunshan Innovation Testing Instruments Co., Ltd., Shenyang TX Testing Instruments Inc., Sinotest Equipment Co., Ltd., Beijing Institute of Metrology, CITIC Dicastal Co., Ltd., Shandong Shancai Testing Instrument Co., Ltd., Laizhou Huayin Testing Instrument Co., Ltd., Shanghai Shangcai Tester machine Co., Ltd., Shanghai Aolong Xingdi Testing Equipment Co., Ltd.
Chief drafting staffs of this document: Tao Zecheng, Zhang Luming, Zhang Jinwei, Luo Xin, Liu Jun, Gao Shuguang, Wang Jingtao, Wei Zhiqing, Xu Zhanping.
The previous versions of this document and the documents which are replaced by this document are as follows:
Metallic materials - Brinell hardness test - Part 2:
Verification and calibration of testing machines
1 Scope
This document specifies methods of direct and indirect verification of testing machines used for determining Brinell hardness in accordance with GB/T 231.1 and also specifies when these two types of verification have to be performed.
The direct verification involves checking that individual machine performance parameters fall within specified limits whereas the indirect verification utilizes hardness measurements of reference blocks, calibrated in accordance with GB/T 231.3, to check the machine’s overall performance.
If a testing machine is also to be used for other methods of hardness testing, it has to be verified independently for each method.
This document is applicable to both fixed location and portable hardness testing machines. For machines that are incapable of satisfying the specified force-time profile, the direct verification of force and testing cycle can be modified by the use of Annex B. 2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the version corresponding to that date is applicable to this document; for undated references, the latest version (including all amendments) is applicable to this document. GB/T 231.1, Metallic materials - Brinell hardness test - Part 1: Test method (GB/T 231.1-2018, ISO 6506-1:2014, MOD)
GB/T 231.3, Metallic materials - Brinell hardness test - Part 3: Calibration of reference blocks (GB/T 231.3-2022, ISO 6506-3:2014, MOD)
GB/T 4340.1, Metallic materials - Vickers hardness test - Part 1: Test method (GB/T 4340.1-2009, ISO 6507-1:2005, MOD)
GB/T 13634, Metallic materials - Calibration of force-proving instruments used for the verification of uniaxial testing machines (GB/T 13634-2019, ISO 376:2011, IDT) GB/T 36416.1, Testing machine vocabulary - Part 1: Material testing machines type of illumination shall remain unchanged. No mean measured diameter shall differ from the certified mean diameter of the reference indentation by more than ±0.5% 2. 5.5 Verification of the testing cycle
5.5.1 The testing cycle is to be verified by the testing machine manufacturer at the time of manufacture and when the testing machine undergoes repair which might have affected the testing cycle. Verification of the testing cycle at other times is as specified in Table 4.
5.5.2 The testing cycle shall be verified to conform with the testing cycle defined in GB/T 231.1, taking into account any uncertainty associated with the timing measurements.
6 Indirect verification
6.1 Indirect verification should be carried out at a temperature of (23 ± 5) °C by means of reference blocks calibrated in accordance with GB/T 231.3. If the verification is made outside of this temperature range, this shall be reported in the verification report. The test and bottom surfaces of the reference blocks and the surfaces of indenters shall not contain any additives or corrosion products.
6.2 The testing machine shall be verified for each test force and for each size of ball used. For each test force, at least two reference blocks shall be selected from the hardness ranges specified in Table 2 (for 0.102 × F/D2 = 30) and Table 3 (for other force-diameter indices).
The two reference blocks shall be taken from different hardness ranges, if possible. 6.3 If this indirect verification is not the one immediately following a direct verification, the reference indentation on each reference block shall be measured, with the same type of illumination that was used during the machine’s previous direct verification. For each indentation, the difference between the mean measured value and the certified mean diameter shall not exceed ±0.5%2. If preferred, this check can instead be made on a similarly sized indentation in a separate reference block.
6.4 On each reference block, five indentations shall be uniformly distributed over the test surface and measured. The test shall be made in accordance with GB/T 231.1. 6.5 For each reference block, let d1, d2, d3, d4, and d5 be the mean values of the measured diameters of the indentations, arranged in increasing order of magnitude, and ̅ is calculated using Formula (1):

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