GB/T 4340.2-2012 Metallic materials - Vickers hardness test - Part 2: Verification and calibration of testing machines
1 Scope
This part of GB/T 4340 specifies the inspection and calibration methods for the Vickers hardness testing machine (hereinafter referred to as the testing machine) used to determine Vickers hardness according to GB/T 4340.1.
It specifies a direct verification method for checking the main functions of the machine operation, and an indirect method suitable for the overall checking of the machine. The indirect method may be used on its own for periodic routine checking of the machine in service.
If a testing machine is also to be used for other methods of hardness test, it shall be verified independently for each method.
This part is also applicable to portable hardness testing machines.
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 4340.3 Metallic materials - Vickers hardness test - Part 3: Calibration of reference blocks (GB/T 4340.3-2012, ISO 6507-3: 2005, MOD)
GB/T 7997 Hardmetals - Vickers hardness test (eqv ISO 3878: 1983)
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 verification of uniaxial testing machines, IDT)
3 General requirements
Before a Vickers hardness testing machine is verified, the machine shall be checked to ensure that it is properly set up in accordance with the manufacturer's instructions:
a) the plunger holding the indenter is capable of sliding in its guide;
b) the indenter-holder is firmly mounted in the plunger;
c) the test force can be applied and removed without shock or vibration and in such a manner that the readings are not influenced;
d) if the measuring system is integral with the machine:
——the change from removing the test force to measuring the indentation does not influence the readings;
——illumination does not affect the readings;
——the center of the indentation is in the center of the field of view, if necessary.
Foreword i
1 Scope
2 Normative references
3 General requirements
4 Direct verification
5 Indirect verification
6 Intervals between verifications
7 Verification report/calibration certificate
Annex A (Informative) Notes on diamond indenters
Annex B (Informative) Measurement uncertainty of the calibration results of the hardness testing machine
