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“Metallic Materials - Brinell Hardness Test” (GB/T 231) is classified into the following four parts:
- 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 is Part 3 of GB/T 231.
This part is drafted according to the rules specified in GB/T 1.1-2009.
This part supersedes "Metallic Brinell Hardness Test - Part 3: Calibration of Hardness Reference Blocks" (GB/T 231.3-2002). Compared with GB/T 231.3-2002, the main technical changes are as follows:
- The name is modified;
- The introduction is modified (see introduction and introduction of 2002 edition);
- National standard "Hardmetals - Vickers Hardness Test" (GB/T 7997-1987) quoted in normative reference list in Chapter 2 is deleted (see Chapter 2 and Chapter 2 of 2002 edition);
- Informative annex "Uncertainty of the Mean Hardness Value of Reference Block" is added (see Annex A).
This part is modified by adopting international standard "Metallic Materials - Brinell Hardness Test - Part 3: Calibration Of Reference Blocks" (ISO 6506-3:2005) (Second Edition) with redrafting method and is consistent with ISO 6506-3:2005 in text structure and technical content.
Technical differences between this part and ISO 6506-3:2005 and the reasons are:
- Foreword of ISO 6506-3:2005 is deleted and is re-prepared;
- Adjustment in "Normative References" of this part has technical differences to meet the technical specification in China; the adjustment contents embodied a concentrated reflection in Chapter 2 "Normative References" and the specific adjustments are as follows:
ISO 6506-1 is superseded by GB/T 231.1 modified by adopting international standard (see 4.7, Chapter 5 and Annex A);
ISO 6506-2:2005 is superseded by GB/T 231.2-2012 modified by adopting international standard (see Chapter 1, 4.1, 4.5, 4.8 and A.1)
ISO 4287 is superseded by GB/T 3505 identical to the international standard (see 3.4);
ISO 376 is superseded by GB/T 13634 identical to the international standard (see 4.4);
- Symbol “U” in Formula (1) of 7.1 is superseded by “J”, symbol "Urel" in Formula (2) and Table 4 is superseded by "Jrel";
- Some incorrect calculation results and data in Table A.2 are corrected and the corrected place are noted with underline;
- Bibliography is deleted.
Technical differences exist between this part and ISO 6506-3:2005 and clauses involving these differences are indicated by perpendicular single line (|) at page margin.
The following editorial changes are made in this part:
- "this part of ISO 6506" is changed to "this part";
- English decimal point symbol "," is superseded by idiomatic Chinese decimal point symbol ".".
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. Issue organization of this document shall not be held responsible for identifying any or all such patent rights.
This part is proposed by China Machinery Industry Federation.
This part is under the jurisdiction of the National Technical Committee on Testing Machines of Standardization Administration of China (SAC/TC122).
Drafting organizations of this part: Quanzhou Fengze Donghai Instrument Hardness Block Plant, Changchun Research Institute for Mechanical Science Co ., Ltd., Laizhou Huayin Testing Instrument Co., Ltd. and Shenzhen Huace Detection Technology Co., Ltd..
Chief drafting staff of this part: Chen Zhiming, Wang Xuezhi, Ma Guoyi, Zhou Qiaoyun, Xu Zhonggen and Guo Bing.
The previous editions of standard superseded by this part are as follows:
- GB 6270-1986 and GB/T 6270-1997;
- GB/T 231.3-2002.
Introduction
In this part of GB/T 231, only the use of the hardmetal ball indenter is specified.
The designation of the Brinell hardness is HBW and should not be confused with the former designation HB, or HBS when a steel ball indenter was used.
Metallic Materials - Brinell Hardness Test - Part 3: Calibration of Reference Blocks
1 Scope
This part of GB/T 231 specifies a method for the calibration of reference blocks to be used in the indirect verification of Brinell hardness testing machines as described in GB/T 231.2-2012.
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the normative document (including any amendments) applies.
GB/T 231.1 Metallic Materials - Brinell Hardness Test - Part 1: Test Method (GB/T 231.1-2009, ISO 6506-1:2005, MOD)
GB/T 231.2-2012 Metallic Materials - Brinell Hardness Test - Part 2: Verification and Calibration of Testing Machines (ISO 6506-2:2005, MOD)
GB/T 3505 Geometrical Product Specifications (GPS) - Surface Texture: Profile Method - Terms, Definitions and Surface Texture Parameters (GB/T 3505-2009, ISO 4287:1997, IDT)
GB/T 13634 Calibration of Force-Proving Instruments Used for the Verification of Uniaxial Testing Machines (GB/T 13634-2008, ISO 376:2004, Metallic Materials - Calibration of Force-proving Instruments Used for the Verification of Uniaxial Testing Machines, IDT)
3 Manufacture of Reference Blocks
3.1 The block shall be specially manufactured for use as a reference block.
Note: Attention is drawn to the need to use a manufacturing process which will give the necessary homogeneity, stability of structure and uniformity of surface hardness.
3.2 Each metal block to be calibrated shall be of a thickness not less than:
- 16mm for 10mm balls;
- 12mm for 5mm balls;
- 6mm for balls (＜5mm).
Note: 12mm for 10mm balls may be used only if the hardness of the reference block is greater than 150 HBW.
3.3 The reference blocks shall be free of magnetism. It is recommended that the manufacturer shall ensure that the blocks, if of steel, have been demagnetized at the end of the manufacturing process.
3.4 The flatness and parallelism of two surfaces of the reference block shall be in accordance with Table 1.
3.5 The test surface shall be free from scratches which interfere with the measurement of the indentations (see Table 1).
3.6 To verify that no material is subsequently removed from the reference block, the thickness at the time of calibration shall be marked on it to the nearest 0.1mm, or an identifying mark shall be made on the test surface [see 8.1.e)].
Table 1 Requirements for the Reference Block
4 Standard Machine
4.1 In addition to fulfilling the general requirements specified in Chapter 3 of GB/T 231.2-2012, the standard Brinell hardness machine shall also meet the requirements given in 4.2 to 4.8.
4.2 The machine shall be verified directly in intervals not exceeding twelve months.
Direct verification involves:
a) Calibration of the test force;
b) Verification of the indenter;
c) Calibration of indenter measuring device;
d) Verification of the testing cycle, if this is not possible, at least the force versus time behavior.
4.3 The instruments used for verification and calibration shall be traceable to national standards.
4.4 Each test force shall be measured using a standard dynamometer of Class 0.5 or better specified GB/T 13634 and the measurement shall agree with the nominal value to within ±0.1%.
4.5 The indenters shall be verified and shall meet the requirements given in 4.3 of GB/T 231.2-2012, with the exception that the tolerances on the diameter of the balls shall meet requirements given in Table 2.
Foreword I
Introduction III
1 Scope
2 Normative References
3 Manufacture of Reference Blocks
4 Standard Machine
5 Calibration Procedure
6 Number of Indentations
7 Uniformity of Hardness
8 Marking
9 Validity
Annex A (Informative) Uncertainty of the Mean Hardness Value of Reference Block
