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GB/T 17394.2-2022 English PDF (GBT17394.2-2022)

GB/T 17394.2-2022 English PDF (GBT17394.2-2022)

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GB/T 17394.2-2022: Metallic materials - Leeb hardness test - Part 2: Verification and calibration of hardness testers
This document specifies the methods for the direct inspection and indirect inspection of the Leeb hardness testers (hereinafter referred to as hardness testers) in accordance with GB/T 17394.1. The direct inspection is suitable for checking whether the performance parameters of the hardness testers are within the specified range. The indirect inspection is to use the hardness value of the reference Leeb hardness test blocks calibrated in accordance with GB/T 17394.3 to check the overall performance of the hardness testers in the direction of gravity. Indirect inspection can be independently applied to regular routine checks of in-use hardness testers.
GB/T 17394.2-2022
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 19.060; 77.040.10
CCS N 71
Replacing GB/T 17394.2-2012
Metallic Materials - Leeb Hardness Test - Part 2:
Verification and Calibration of Hardness Testers
(ISO 16859-2:2015, Metallic Materials - Leeb Hardness Test - Part 2: Verification and Calibration of the Testing Devices, MOD)
ISSUED ON: JULY 11, 2022
IMPLEMENTED ON: FEBRUARY 1, 2023
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
Introduction ... 5
1 Scope ... 6
2 Normative References ... 6
3 Terms and Definitions ... 6
4 General Requirements ... 6
5 Direct Inspection ... 7
5.1 General Rules ... 7
5.2 Technical Parameters ... 7
5.3 Inspection of Mass and Geometric Dimensions of Impact Body ... 9
5.4 Inspection of Geometric Dimensions and Hardness of Ball Head ... 9
5.5 Inspection of Geometric Dimensions of Support Ring ... 9
5.6 Inspection of Impact Velocity ... 10
5.7 Indirect Inspection of Hardness Tester ... 10
6 Indirect Inspection ... 10
6.1 General Rules ... 10
6.2 Method ... 11
6.3 Coefficient of Variation (V) ... 11
6.4 Relative Error of Indication ... 12
6.5 Uncertainty of Measurement ... 13
7 Inspection Cycle ... 13
8 Inspection Report and / or Calibration Certificate ... 14
Appendix A (informative) Measurement Uncertainty of Calibration Results of Hardness Testers ... 15
Appendix B (informative) Direct Inspection of Single-coil Hardness Tester ... 19 Bibliography ... 21
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 17394 Metallic Materials - Leeb Hardness Test. GB/T 17394 has issued the following parts:
---Part 1: Test Method;
---Part 2: Verification and Calibration of Hardness Testers;
---Part 3: Calibration of Reference Test Blocks;
---Part 4: Tables of Hardness Values Conversation.
This document serves as a replacement of GB/T 17394.2-2012 Metallic Materials - Leeb Hardness Test - Part 2: Verification and Calibration of Hardness Testers. In comparison with GB/T 17394.2-2012, the main technical changes are as follows:
---The DC-type impact device is deleted (see Chapter 1 of Version 2012); ---The inspection items are modified (see Chapter 4; Chapter 3 of Version 2012); ---The inspection of impact velocity and support ring is added (see 5.1.3); ---The relevant requirements for direct inspection are modified (see Chapter 5; Chapter 4 of Version 2012);
---The relevant requirements for indirect inspection are added (see 6.1.2 ~ 6.1.4); ---The hardness range of the reference Leeb hardness test blocks is modified (see Table 2; Table 4 of Version 2012);
---The inspection cycle is modified (see Chapter 7; Chapter 6 of Version 2012); ---The type of impact device for hardness testers is deleted (see Appendix A of Version 2012);
---The direct inspection of the single-coil hardness tester is added (see Appendix B). This document modifies and adopts ISO 16859-2:2015 Metallic Materials - Leeb Hardness Test - Part 2: Verification and Calibration of the Testing Devices.
There are technical differences between this document and ISO 16859-2:2015, and the clauses involved in these differences have been marked by a single vertical line () in the outer margin of the document. The specific technical differences and the causes for these differences are as follows:
Metallic Materials - Leeb Hardness Test - Part 2:
Verification and Calibration of Hardness Testers
1 Scope
This document specifies the methods for the direct inspection and indirect inspection of the Leeb hardness testers (hereinafter referred to as hardness testers) in accordance with GB/T 17394.1.
The direct inspection is suitable for checking whether the performance parameters of the hardness testers are within the specified range. The indirect inspection is to use the hardness value of the reference Leeb hardness test blocks calibrated in accordance with GB/T 17394.3 to check the overall performance of the hardness testers in the direction of gravity. Indirect inspection can be independently applied to regular routine checks of in-use hardness testers. This document is applicable to hardness testers equipped with D, S, E, D + 15, DL, C and G- type impact devices.
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 4340.1 Metallic Materials - Vickers Hardness Test - Part 1: Test Method (GB/T 4340.1- 2009, ISO 6507-1:2005, MOD)
GB/T 17394.1 Metallic Materials - Leeb Hardness Test - Part 1: Test Method GB/T 17394.3-2022 Metallic Materials - Leeb Hardness Test - Part 3: Calibration of Reference Test Blocks (ISO 16859-3:2015, MOD)
3 Terms and Definitions
This document does not have terms or definitions that need to be defined. 4 General Requirements
Before inspecting the hardness testers, they shall be checked to ensure that the hardness testers are correctly installed and operated in accordance with the manufacturer’s instructions. 5.3 Inspection of Mass and Geometric Dimensions of Impact Body
5.3.1 The mass of the impact body shall satisfy the requirements specified in Table 1. 5.3.2 The impact body shall consist of a ball head and a bracket. If the impact signal is read through the electromagnetic induction coil, then, the impact body shall contain a permanent magnet.
5.3.3 For D, D + 15, S, E and C-type impact devices, the tip of the ball head shall protrude from the grip by at least 0.3 mm. For G-type impact device, the tip of the ball head shall protrude from the grip by at least 0.6 mm. For DL-type impact device, the diameter of the gripped round steel bar is (2.5  0.1) mm, the length is (55.15  0.1) mm and the tip of the ball head shall protrude from the grip by at least 2 mm.
5.4 Inspection of Geometric Dimensions and Hardness of Ball Head
5.4.1 In order to inspect the geometric dimensions and hardness of the ball head, randomly take a sample from a batch of balls to test its diameter and hardness. This batch of balls shall be provided with a certificate of conformity or evidence of the required hardness. Balls subjected to the hardness test shall be discarded.
5.4.2 The diameter of the ball head shall be determined by measuring different positions on the ball to obtain the arithmetic mean of not less than three diameter values. The difference between a single measured value at any position and its nominal value shall satisfy the requirements in Table 1.
5.4.3 The ball head shall be made of tungsten-cobalt cemented carbide, ceramics or synthetic diamond (as shown in Table 1). The hardness test shall be carried out in accordance with the stipulations of GB/T 4340.1, and the hardness value shall comply with the stipulations of Table 1. The steel ball can be tested directly on the spherical surface, or sliced inside the steel ball. Synthetic diamond balls do not need to be inspected for hardness.
5.4.4 When conducting an inspection under a magnifying glass of 100 times, the surface of the ball head shall be smooth and free of defects.
5.5 Inspection of Geometric Dimensions of Support Ring
The thickness of the support ring shall be determined by measuring different positions on the support ring to obtain the arithmetic mean of not less than 3 thickness values. The difference between a single measured value at any position and its nominal value shall not exceed 0.1 mm. 5.6 Inspection of Impact Velocity
5.6.1 The impact velocity shall be directly measured in the direction of gravity, and the velocity value shall be read at the maximum height above the surface of the test piece listed in Table 1. 5.6.2 If a direct inspection of the impact velocity is not possible, then, conduct an indirect inspection on the impact velocity. For example: replace the impact body of the impact device with a reference impact body that complies with the parameters specified in Table A.1 of GB/T 17394.3-2022. Connect the impact device to the standard display device and vertically downward test the reference test block, compare the displayed measurement signal with the standard signal value, as shown in Appendix B. The signal waveform response before the impact shall be peculiar to the hardness tester and irrelevant to the material being tested. 5.7 Indirect Inspection of Hardness Tester
After the direct inspection is qualified, in accordance with the requirements of Chapter 6, conduct the indirect inspection.
6 Indirect Inspection
6.1 General Rules
6.1.1 The indirect inspection should be carried out within the temperature range of (23  5) C, and the reference Leeb hardness test block used shall comply with the requirements of GB/T 17394.3. If the inspection is carried out beyond this temperature range, then, it shall be indicated in the inspection report / calibration certificate.
6.1.2 Conduct a visual inspection on the appearance of the impact device, impact body, support ring and display device, and there shall be no damage.
6.1.3 The resolution of the display device shall be at least 1 HL.
6.1.4 For the hardness testers, select three reference Leeb hardness test blocks from the hardness range specified in Table 2 to test the hardness value (one reference Leeb hardness test block shall be selected for each hardness range).
Appendix A
(informative)
Measurement Uncertainty of Calibration Results of Hardness Testers
NOTE: Figure C.1 of ISO 16859-1:2015 shows the structural diagram of the metrological traceability chain used to define and distinguish each hardness scale.
A.1 Direct Inspection of Hardness Tester
A.1.1 Inspection of impact body and support ring
The impact body is equipped with a ball head and support ring made of tungsten-cobalt cemented carbide, ceramics or synthetic diamond, and cannot be inspected or calibrated on site. The geometrical deviations, physical properties and chemical composition of the ball head need to be proved by a valid inspection certificate issued by an accredited laboratory (see 5.3). A.1.2 Use reference impact body and reference display unit for the inspection of impact device
Under laboratory conditions, use a reference impact body and reference display unit to conduct an indirect inspection on the impact device (see 5.4).
A.2 Indirect Inspection of Hardness Tester
By using the reference Leeb hardness test block for the indirect inspection, the overall performance of the hardness tester can be checked. Meanwhile, in accordance with the calibration value of the reference Leeb hardness test block, determine the coefficient of variation and relative error of indication of the hardness tester.
The composite standard uncertainty during the indirect inspection of the hardness tester (see ISO/IEC Guide 98-3) shall be calculated in accordance with Formula (A.1): Where,
uCRM---the standard uncertainty provided by the calibration certificate of the reference Leeb hardness test block (k = 1);
uCRMD---for the reference Leeb hardness test block, since the latest calibration, the standard uncertainty introduced by the drift of the hardness value with time (when the reference Leeb hardness test block that satisfies the requirements of the standards is used for inspection, this item can be ignored);
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