Metallic Materials — Leeb Hardness Test — Part 2: Verification and Calibration of Hardness Testers
1 Scope
This document specifies methods for direct and indirect verification of hardness testers (hereinafter referred to as “testers”) used for determining Leeb hardness in accordance with GB/T 17394.1.
The direct verification involves checking that performance parameters of the tester fall within specified limits. Indirect verification utilizes hardness measurements of reference test blocks, calibrated in accordance with GB/T 17394.3, to check the overall performance of the tester in the direction of gravity. The indirect verification can be used on testers for the periodic performance checking in service.
This document is applicable to the testers with types D, S, E, D+15, DL, C and G impact devices.
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 referenced document (including any amendments) applies.
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
No terms and definitions are listed in this document.
4 General Requirements
Before a Leeb hardness tester is verified, the instrument shall be checked to ensure that it is properly set up and operating in accordance with the manufacturer’s instructions.
Especially it shall be checked that:
a) the impact body is correctly installed in the guide tube;
b) the support ring is mounted tightly to the bottom of the impact device;
c) cables are correctly connected, if applicable;
d) the settings of the indicating unit are correct.
5 Direct Verification
5.1 General
5.1.1 Direct verification should be carried out at a temperature of (23 ± 5)°C. If the verification is made outside this temperature range, this shall be reported in the verification report.
5.1.2 The instruments used for verification shall be traceable to national measurement standards.
5.1.3 Direct verification is comprised of the following:
a) verification of mass and geometry of impact body in accordance with 5.3;
b) verification of geometry of indenter ball, and of hardness of ball except for type E, in accordance with 5.4;
c) verification of geometry of support ring in accordance with 5.5;
d) verification of impact velocity in accordance with 5.6.
5.2 Technical parameters
Technical parameters for reference in direct calibrations of Leeb impact devices are specified in Table 1.
Foreword II
Introduction IV
1 Scope
2 Normative References
3 Terms and Definitions
4 General Requirements
5 Direct Verification
5.1 General
5.2 Technical parameters
5.3 Verification of mass and geometry of impact body
5.4 Verification of geometry and hardness of indenter ball
5.5 Verification of geometry of support ring
5.6 Verification of impact velocity
5.7 Indirect verification of testers
6 Indirect Verification
6.1 General
6.2 Procedure
6.3 Variation coefficient (V)
6.4 Relative error of readings
6.5 Measurement uncertainty
7 Intervals between Verifications
8 Verification Report/Calibration Certificate
Annex A (Informative) Measurement Uncertainty of Calibration Results of Leeb Hardness Tester
Annex B (Informative) Direct Verification of Single Coil Instrument
Bibliography
