GB/T 231.2-2022Metallic materials—Brinell 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 231 Metallic materials - Brinell hardness test. The

following parts have been released for GB/T 231:

-- Part 1: Test method;

-- Part 2: Verification and calibration of testing machines;

-- Part 3: Calibration of reference blocks;

-- Part 4: Tables of hardness values.

This document replaces GB/T 231.2-2012 Metallic materials - Brinell hardness test -

Part 2: Verification and calibration of testing machines; compared with GB/T 231.2-

2012, the major technical changes are as follows:

-- According to the force-diameter indices, MODIFY the hardness ranges of low,

medium and high reference blocks used for indirect verification of hardness

testing machine, and the relative repeatability of the hardness testing machine

corresponding to different hardness ranges of the tested hardness testing machine,

as well as the permissible error (see 6.7 and 6.9; 5.7 and 5.8 of the 2012 edition);

-- ADD Annex B "Verification of hardness testing machines that are incapable of

meeting the specified force/time profile" (see Annex B).

This document adopts the modification of ISO 6506-2:2017 Metallic materials - Brinell

hardness test - Part 2: Verification and calibration of testing machines.

Compared with ISO 6506-2:2017, this document is adjusted, in structure, as follows:

-- CHANGE 5.3.4.1 and 5.3.4.2 in ISO 6506-2:2017 to 5.3.5 and 5.3.6.

There are technical differences between this document and ISO 6506-2:2017, and the

clauses involved in these differences have been marked by a vertical single line (|) in

the outer margin of the document. The specific technical differences and their reasons

are as follows:

-- REPLACE ISO 6506-1 WITH GB/T 231.1, which adopts the international

standard by modification, (see Clause 1, 5.2.4, 5.5.2, 6.4, A.1 and Annex B), to

adapt to the technical conditions in China;

-- REPLACE ISO 6506-3 WITH GB/T 231.3, which adopts the international

standard by modification, (see Clause 1, 5.4.3, 6.1), to adapt to the technical

conditions in China;

-- ADD reference to GB/T 36416.1-2018 (see Clause 3);

-- REPLACE ISO 6507-1 (see 5.3.4.2) WITH GB/T 4340.1, which adopts the

international standard by modification, to adapt to the technical conditions in

China.

This document makes the following editorial changes:

-- MODIFY the numbers "1", "2" and "3" used to indicate "Hardness range of the

hardness testing machine" in the first column of Table 2 and Table 3 to Chinese

characters "low", "medium" and "high", respectively (see 6.7);

-- MODIFY the symbol "×" used to indicate "required inspection items" in Table 4

to the symbol "sqrt", and ADD the symbol "-" to indicate "non-inspected items"

(see Clause 7);

-- NUMBER the unnumbered formulas in Annex A of ISO 6506-2:2017 in sequence

(see Annex A);

Annex A of ISO 6506-2:2017 to the symbol "E" [see Formula (A.10), Formula

(A.13) and Table A.9].

1 Scope

This document specifies methods of direct and indirect verification of testing machines

used for determining Brinell hardness in accordance with GB/T 231.1 and also specifies

when these two types of verification have to be performed.

The direct verification involves checking that individual machine performance

parameters fall within specified limits whereas the indirect verification utilizes hardness

measurements of reference blocks, calibrated in accordance with GB/T 231.3, to check

the machine's overall performance.

If a testing machine is also to be used for other methods of hardness testing, it has to be

verified independently for each method.

This document is applicable to both fixed location and portable hardness testing

machines. For machines that are incapable of satisfying the specified force-time profile,

the direct verification of force and testing cycle can be modified by the use of Annex B.

2 Normative references

The following documents are referred to in the text in such a way that some or all of

their content constitutes requirements of this document. For dated references, only the

version corresponding to that date is applicable to this document; for undated references,

the latest version (including all amendments) is applicable to this document.

GB/T 231.1, Metallic materials - Brinell hardness test - Part 1: Test method (GB/T

231.1-2018, ISO 6506-1:2014, MOD)

GB/T 231.3, Metallic materials - Brinell hardness test - Part 3: Calibration of

reference blocks (GB/T 231.3-2022, ISO 6506-3:2014, MOD)

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 13634, Metallic materials - Calibration of force-proving instruments used for

the verification of uniaxial testing machines (GB/T 13634-2019, ISO 376:2011, IDT)

GB/T 36416.1, Testing machine vocabulary - Part 1: Material testing machines

type of illumination shall remain unchanged. No mean measured diameter shall differ

from the certified mean diameter of the reference indentation by more than ±0.5% 2.

6 Indirect verification