GB/T 230.2-2022 English PDF (GBT230.2-2022)

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GB/T 230.2-2022: Metallic materials - Rockwell hardness test - Part 2: Verification and calibration of testing machines and indenters
GB/T 230.2-2022
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 19.060; 77.040.10
CCS N 71
Replacing GB/T 230.2-2012
Metallic materials - Rockwell hardness test - Part 2:
Verification and calibration of testing machines and
indenters
(ISO 6508-2:2015, MOD)
ISSUED ON: JULY 11, 2022
IMPLEMENTED ON: FEBRUARY 01, 2023
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
Introduction ... 6
1 Scope ... 7
2 Normative references ... 7
3 Terms and definitions ... 8
4 General requirements ... 8
5 Direct inspection by durometer ... 8
5.1 General... 8
5.2 Calibration and inspection of test force ... 9
5.3 Calibration and inspection of indentation depth measuring device ... 9
5.4 Calibration and inspection of test cycle time ... 10
5.5 Calibration and inspection of durometer hysteresis ... 11
6 Indirect inspection of durometer ... 11
6.1 General... 11
6.2 Procedure ... 12
6.3 Repeatability ... 13
6.4 Indication error ... 15
6.5 Measurement uncertainty ... 15
7 Calibration and inspection of Rockwell hardness indenter ... 15
7.1 General... 15
7.2 Diamond cone indenter ... 15
7.3 Ball indenter ... 19
7.4 Identification ... 20
8 Period of direct and indirect inspection ... 21
9 Inspection report ... 21
Appendix A (Normative) Repeatability of durometer ... 23
Appendix B (Informative) Measurement uncertainty of durometer calibration results
... 25
Metallic materials - Rockwell hardness test - Part 2:
Verification and calibration of testing machines and
indenters
1 Scope
This document specifies two inspection methods (direct inspection and indirect
inspection) of the Rockwell durometer, for determining the Rockwell hardness,
according to GB/T 230.1; specifies the inspection method of the Rockwell hardness
indenter.
The direct test method is suitable for checking whether the main parameters related to
the function of the durometer are within the specified tolerances, such as test force,
depth measurement, test cycle time. The indirect test method is suitable for using a set
of calibrated reference blocks, to determine the performance of the durometer, when
measuring materials with known hardness.
The indirect test method can be used alone for regular routine inspections, using
medium durometers.
If the durometer can also be used for the hardness test of other hardness test methods,
the durometer shall be tested separately, according to each method.
This document applies to both stationary durometers and portable durometers.
Note that tungsten carbide alloy ball indenters have been considered as Rockwell
hardness standard ball indenters. The steel ball indenter is limited to use, under the
conditions of Appendix A in GB/T 230.1-2018.
2 Normative references
The contents of the following documents constitute the essential provisions of this
document through normative references in the text. Among them, for dated references,
only the version corresponding to the date applies to this document; for undated
references, the latest version (including all amendments) applies to this document.
GB/T 230.1-2018 Metallic materials - Rockwell hardness test - Part 1: Test method
(ISO 6508-1:2016, MOD)
GB/T 230.3-2022 Metallic materials - Rockwell hardness test - Part 3: Calibration
5.2 Calibration and inspection of test force
5.2.1 Measurements shall be made, for each initial test force F0 (see 5.2.4) and each
total test force F (see 5.2.5) used. As far as practicable, in the entire movement range of
the spindle during the test, the above-mentioned force measurements are made at least
three positions, at certain intervals. The initial test force shall be maintained for at least
2 s.
5.2.2 At each position of the spindle, three readings shall be taken at each test force.
Before each measurement reading, the direction of movement of the spindle shall be
consistent with the direction of movement during the test.
5.2.3 The test force shall be measured, by one of the following two methods:
- Use a standard force measuring instrument, at grade 1 or better than grade 1, that
meets the requirements of GB/T 13634, AND whose return performance has been
calibrated;
- Apply a force within ± 0.2% of indication error, by means of weight of calibrated
mass or other means of equivalent accuracy, so that this force is in balance with the
test force to be detected.
Evidence should be provided to prove that the output of the force-measuring device
does not change by more than 0.2%, during the period of 1 s ~ 30 s, after the step change
of the test force.
5.2.4 Before the main test force F1 is applied and after it is removed, the maximum
tolerance for each measurement of the initial test force F0 shall be ±2.0% of its nominal
value, see formula (B.2). The variation range (maximum value minus minimum value)
of all measured values of initial test force shall not be greater than 1.5% of the nominal
value of F0.
5.2.5 The maximum tolerance for each measurement of the total test force F shall be
±1.0% of its nominal value. The variation range (maximum value minus minimum
value) of all measured values of the total test force shall not be greater than 0.75% of
the nominal value of F.
5.3 Calibration and inspection of indentation depth measuring device
5.3.1 The indentation depth measuring device shall be calibrated, by making the
indenter or indenter seat produce known displacement increments.
5.3.2 When calculated at a 95% confidence level, the expanded uncertainty of the
instrument or gauge block, which is used to test the indentation depth measuring device,
shall not exceed 0.0003 mm.
5.3.3 The indentation depth measuring device shall be tested, at least 4 positions evenly
distributed within the entire working depth range of the durometer, during normal
measurement. For conventional Rockwell hardness scales (A, C, D, B, E, F, G, H, K),
the working depth is 0.25 mm; for superficial Rockwell hardness scales (N, T), the
working depth is 0.1 mm.
5.3.4 The indentation depth measuring device of some durometers has a large stroke;
the position of the working range of the measuring device will change with the thickness
of the specimen. This type of durometer shall be able to be checked electronically, to
ensure continuous operation of the indentation depth measuring device, throughout the
entire travel range. This durometer shall be inspected according to the following steps:
a) Select the three positions of the highest point, the center point, the lowest point of
the total range of the measuring device. Near each of the three positions, use not
less than four displacement increments, at equal intervals of about 0.05 mm, to
test the indentation depth measuring device;
b) Operate the drive and monitor whether the measurement of the displacement is
continuous, over the entire travel range of the drive. The displacement indication
shall be displayed continuously, throughout the entire travel range.
5.3.5 For scales A to K, the indication value of the indentation depth measuring device
shall be accurate to ±0.001 mm, within the measurement range of each scale. For scales
N and T, it shall be accurate to ±0.0005 mm, within the measurement range of each
scale, that is, no more than ±0.5 Rockwell hardness units.
5.4 Calibration and inspection of test cycle time
5.4.1 The test cycle time shall be verified by...