GOST 2999-75

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  ГОСТ 2999-75

GOST 2999−75 (ST SEV 470−77) Metals and alloys. Method for measuring hardness by Vickers (with Changes N 1, 2)

GOST 2999−75
(ST SEV 470−77)

Group B09

STATE STANDARD OF THE UNION OF SSR

METALS AND ALLOYS

Method for measuring hardness by Vickers

Metals and alloys. Vickers hardness test by diamond pyramid

LOCATION 1909

Date of introduction 1976−07−01 *
______________________________
* Expiration date removed
under the protocol No. 5−94 of the Interstate Council
on standardization, metrology and certification
(ISC No. 2, 1993). — Note of the database manufacturer.

APPROVED AND ENTRY INTO ACTION by the Resolution of the State Committee of Standards of the Council of Ministers of the USSR of July 28, 1975 No. 1956

Verified in 1985 by the decree of the State Standard of 27.09.85 N 3118 the validity period was extended to 01.07.93

REPLACEMENT GOST 2999−59

REVERSION (December 1986) with Changes N 1, 2, approved in May 1979, September 1985 (MIS 7−79, 12−85).

This standard establishes a method for measuring Vickers hardness of ferrous and non-ferrous metals and alloys at loads from 9.807 N (1 kgf) to 980.7 N (100 kgf).

The hardness measurement is based on indenting a diamond tip in the form of a regular tetrahedral pyramid in a sample (article) under the action of a load , applied for a certain time, and measuring the diagonals of the print , , remaining on the surface of the sample after removal of the load.

The standard fully corresponds to the ST SEV 470−77 (reference annex 2).

(Changed edition, Rev. N 1, 2).

1. SAMPLE SELECTION METHODS

1.1. When making a sample and preparing its surface, measures must be taken to prevent the possibility of changing the properties of the metal due to heating or cold work.

1.2. The minimum thickness of the sample should be 1.2 times for steel products greater than the diagonal of the print; for products made of non-ferrous metals — 1.5 times.

Note. The minimum thickness of the sample (product) for non-ferrous metals is determined from the nomogram given in the recommended annex 3.


(Changed edition, Amendment No. 1).

1.3. When measuring hardness on curvilinear surfaces, the radius of curvature should be at least 5 mm.

Note. To determine the hardness on samples with a radius of curvature less than 5 mm, the correction factors used for cylindrical and spherical surfaces are applied, depending on the value of the ratio , given in the recommended annex 4.

(Changed edition, Amendment No. 1).

2. EQUIPMENT

2.1. The device for measuring hardness must comply with the requirements of GOST 23677−79 and this standard.

The diamond tip must meet the requirements of GOST 9377−81 .

2.3. Exemplary measures of hardness must comply with the requirements of GOST 9031−75 .

3. PREPARATION FOR TEST

3.1. Before measuring the hardness, samples (articles) are inspected.

3.2. The surface of the test sample should have a roughness of not more than 0.16 μm in accordance with GOST 2789−73 and be free of oxide film and foreign matter.

3.3. When measuring hardness, perpendicularity of the application of the acting force to the test surface must be ensured.

3.4. The support surface of the table must be clean. The sample should be rigid and stable on the stand.

3.5. When measuring the hardness of a diamond pyramid, the following loads are used: 9,807 (1); 19.61 (2); 24.52 (2.5); 29.42 (3); 49.03 (5); 98.07 (10); 196.1 (20); 294.2 (30); 490.3 (50); 980.7 (100) H (kgf).

To obtain a more accurate measurement of hardness, the load should be as large as possible, and no signs of deformation should be visible on the back of the sample.

Note. To determine the hardness of ferrous metals and alloys, loads from 49.03 N (5 kgf) to 980.7 N (100 kgf) are used; for copper and its alloys — from 24.52 N (2.5 kgf) to 490.3 N (50 kgf); for aluminum alloys — from 9.807 N (1 kgf) to 980.7 N (100 kgf).

(Changed edition, Amendments No. 1, 2).

4. CONDUCTING THE TEST

4.1. When measuring hardness, the following conditions must be met:

a) smooth increase in load to the required value;

b) maintaining the constancy of the applied load during the set time.

4.2. Duration of exposure under load should be 10−15 seconds.

4.3. If there are special indications in the standards or technical conditions for metal products, it is allowed to carry out tests with a longer holding time under load. In this case, the tolerance for exposure should be ± 2 s.

4.4. The distance between the center of the print and the edge of the sample or the edge of the adjacent print should be at least 2.5 times the diagonal of the print.

4.5. If the thickness of the test layer is unknown, several measurements should be made at different loads. If the hardness changes, the load should be reduced until, with two adjacent loads, the hardness is close in value or coincides.

4.6. The test is carried out at a temperature of ° C.

In case of disagreement in the measurement of hardness, the tests should be carried out at temperatures (20 ± 2) ° C in temperate climates and at (27 ± 2) ° C in tropical climates.

(Introduced additionally, Amendment No. 1).

4.7. The number of prints in the determination of hardness is indicated in the normative and technical documentation for metal products.

(Introduced additionally, Amendment No. 1).

5. PROCESSING OF RESULTS

5.1. Vickers hardness () is calculated by the formula

Where Load, N.

Where  — load, kgf;

 — the angle between the opposite faces of the pyramid at the vertex is equal to 136 °;

 — the arithmetic mean of the lengths of both diagonals of the print after the load is removed, mm.

(Changed edition, Change No. 2).

5.2. To determine the Vickers hardness, the arithmetic mean of the lengths of both diagonals is taken (see the drawing). The difference between the diagonals of one print should not exceed 2% of the smaller of them.

For anisotropic materials, the resulting difference in lengths of two diagonals of one print may not fit within the specified tolerance. The tolerance for this difference should be specified in the standards or specifications for metal products.

(Changed edition, Change No. 2).

5.3. Measurement of diagonals up to 0.2 mm in length should be made with an error of not more than ± 0,001 mm, and for diagonals longer than 0,2 mm — with an error of not more than ± 0,5%.

5.4. Vickers hardness under test conditions = 294.2 N (30 kgf) and holding time under load of 10−15 s — is denoted by figures characterizing the hardness value and letters . Under other test conditions after the letters indicates the load and holding time.

Examples of designation: 500  — Vickers hardness, obtained with load = 30 kgf and holding time 10−15 s;

220 10/40 — Vickers hardness, obtained with a load of 98.07 (10 kgf) and a holding time of 40 s.

(Changed edition, Amendments No. 1, 2).

5.5. Vickers hardness, calculated by this formula, depending on the length of the diagonal of the print at the standard values of their load , is given in the Appendix.

6. PROTOCOL OF TEST

The test report shall state:

magnitude of the load;

hardness values;

duration of exposure under load;

the diagonal of the print (in the case of the test in accordance with 5.2);

designation of the sample.

(Introduced additionally, Amendment No. 1).

APPENDIX 1. HARDNESS IN TEST OF DIAMOND PYRAMIDES BY VICKERS

ANNEX 1

Load 9,807 (1 kgf)

Table 1

Note. To calculate the numbers of hardness at loads of 19.61 (2), 24.52 (2.5), 29.42 (3) N (kgf), the hardness value should be multiplied by 2.0; 2.5; 3.0.

table 2

Note. To calculate the numbers of hardness at a load of 490.3 N (50 kgf), the hardness value must be multiplied by 10.