GB/T 4340.2-2025Metallic materials - Vickers hardness test - Part 2: Verification and calibration of testing machines (English PDF)

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 4340 Metallic Materials - Vickers Hardness Test. GB/T 4340

has issued the following parts.

---Part 1.Test Method;

---Part 2.Verification and Calibration of Testing Machines;

---Part 3.Calibration of Hardness Reference Blocks;

---Part 4.Tables of Hardness Values.

This document serves as a replacement for GB/T 4340.2-2012 Metallic Materials - Vickers

Hardness Test - Part 2.Verification and Calibration of Testing Machines. In comparison with

GB/T 4340.2-2012, apart from structural adjustments and editorial modifications, the main

technical changes are as follows.

---The Scope is modified, and content of hardness testers, to which, this document does

not apply, is added (see Chapter 1; Chapter 1 of Version 2012);

---The test method for when the test force is not affected by the spindle position is modified,

and a simplified method for testing the test force at only one position of the spindle is

added (see 5.2.1; 4.2.1 of Version 2012);

---The requirements for test force deviation are modified, and the maximum permissible

relative deviation of the test force for the small force range of "0.009807 N ~ 0.09807

N" is added to the original requirements (see Table 1; Table 1 of Version 2012);

---The requirements for the indenter verification instruments are added (see 5.3.2);

---For the measurement of the intersection line of the indenter top, the minimum force

value is modified from "0.09807 N" into "0.009807 N" (see Table 2; Table 2 of Version

2012);

---The requirements for indenter verification / calibration certificate are added (see 5.3.6

and 8.2);

---The requirements for verification and calibration of diagonal measurement system are

modified (see 5.4; 4.4 of Version 2012);

---The requirements for maximum permissible error of standard indentations are modified

(see 6.3; 5.2 of Version 2012);

Metallic Materials - Vickers Hardness Test - Part 2.

Verification and Calibration of Testing Machines

1 Scope

This document specifies the verification and calibration methods for Vickers hardness tester

and diagonal measurement system used to determine Vickers hardness in accordance with GB/T

4340.1.

The direct verification method specified in this document applies to the verification and

calibration of the hardness tester, indenter and diagonal measurement system. The indirect

verification method applies to the verification of the entire Vickers hardness tester using a

standard block.

If the Vickers hardness tester is also used for hardness testing by other methods, then, the

Vickers hardness tester shall be respectively verified in accordance with the corresponding

methods.

This document also applies to the verification and calibration of portable Vickers hardness

testers.

This document does not apply to hardness testers that measure hardness using other different

principles (for example, ultrasonic impedance method).

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-

2024, ISO 6507-1.2023, MOD)

GB/T 4340.3 Metallic Materials - Vickers Hardness Test - Part 3.Calibration of Reference

Blocks (GB/T 4340.3-2025, ISO 6507-3.2018, 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)

3 Terms and Definitions

This document does not have terms or definitions that need to be defined.

4 General Requirements

Before verification, the Vickers hardness tester (hereinafter referred to as the "hardness tester")

shall be checked to ensure that it is correctly installed in accordance with the manufacturer's

instructions.

The following items shall be particularly checked.

a) The spindle fixing the indenter can slide in its guide rail without friction or excessive

lateral deflection.

b) The indenter shank is securely mounted in the spindle bore.

c) The application and removal of the test force are free from shock, vibration or

overload that may affect the measurement results.

d) Diagonal measurement system.

1) If the diagonal measurement system is integrated into the main unit, then, the

transition from test force removal to indentation measurement shall not affect the

reading;

2) The illumination device of the measuring microscope produces uniform

illumination throughout the entire field of view, providing sufficient contrast

between the indentation and the surrounding surface to allow clear identification

of its boundaries;

3) Where necessary, the center of the indentation shall be located in the center of

the field of view.

NOTE. the detailed rules on the verification and calibration of hardness testers specified in this

document are subject to continuous development and improvement. When a hardness

tester is required to meet a specified tolerance, that tolerance already includes the

uncertainty associated with the measurement instrument and / or reference standard used.

Therefore, any further correction for this uncertainty (e.g., reducing the tolerance through

measurement uncertainty) is inappropriate. This applies to all measurements made during

direct or indirect verification of a hardness tester.

5 Direct Verification