GOST 22761-77

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  ГОСТ 22761-77

GOST 22761−77 Metals and alloys. Method of measuring hardness Brinell portable hardness static effect

GOST 22761−77
Group B09

INTERSTATE STANDARD

METALS AND ALLOYS

Method of measuring hardness Brinell portable hardness static effect

Metals and alloys. Method of measuring the Brinell hardness by static action portable hardness meters

ISS 77.040.10

Date of introduction 1979−01−01

The decision of the State standards Committee of the USSR Council of Ministers dated October 31, 1977 N 2554 date of introduction is established 01.01.79

Limitation of actions taken by Protocol No. 3−93 Interstate Council for standardization, Metrology and certification (ICS 5−6-93)

REPRINTING. April 2003
This standard applies to ferrous and nonferrous metals and alloys, and establishes the method of measuring hardness Brinell hardness from about 78.5 to 5884 MPa (8−600 kgf/mm) portable hardness testers to static action at a temperature from 0 °C to 40 °C.

Brinell hardness number is medium voltage in the hole during indentation of the ball load is proportional to the square of the diameter of the ball.

1. EQUIPMENT

1.1. As a test apparatus used portable devices static operation, enables:

a smooth increase of the load;

ensure continuity of the applied load for the required time. The error of the device values of the test load shall not exceed ±1%;

application of the current efforts perpendicular to the surface of the test items (sample).

1.2. Used in the hardness measurement Brinell balls must meet the following requirements:

material for balls, heat treated steel with a Vickers hardness not less than 850 units when measuring hardness Brinell up to 4410 MPa (450 kgf/mm) and tungsten carbide — when measuring hardness Brinell from 4413 to 5884 MPa (450 to 600 kgf/mm);

the diameter of used balls — 1 mm and 2.5 mm. is allowed to use balls with a diameter of 5 mm and 10 if it allows the design of the device;

limit deviations of the diameter of the steel ball should conform to the group VHOST 3722−81, and the diameter of the ball, tungsten carbide should not exceed ±0,0035 mm. When using a ball made of tungsten carbide with a diameter of 5 and 10 mm, limit deviations should not exceed, respectively, ±0,0040 ±0,0045 mm;

the roughness parameter of the surface of the ball should be no more than 0,040 µm according to GOST 2789−73.

1.3. Steel ball, after showing hardness measurement of residual deformation in excess of specified in GOST 3722−81 maximum deviation for group b, or any surface defect and the ball of tungsten carbide, which showed after measuring the residual deformation in excess of the limit deviation specified in claim 1.2 must be replaced by others, and the corresponding measurement should be considered invalid.

1.4. Indentation diameter is measured using a microscope with a margin error, not exceeding:

±0,003 mm — when measuring the hardness of a ball with a diameter of 1 mm;

±0,006 mm — when measuring the hardness of a ball with a diameter of 2.5 mm.

1.5. Periodic testing of portable devices, the static effect hardness on the Brinell hardness shall be in accordance with GOST 8.398−80.

2. PREPARATION FOR CONTROL

2.1. The roughness parameter of the surface of the item (sample) in place of the test must be not more than =0,32 µm according to GOST 2789−73.

2.2. In preparing the surface of the test items (sample) it is necessary to take measures to prevent a possible change in the hardness of the test items (sample) due to heating or cold working of the surface when machined.

2.3. Tested product (sample) should not shift in the measurement of hardness.

2.4. The minimum thickness of the test items (sample) should be at least 8 times the depth of the imprint.

2.5. The diameter of the ball load , the minimum thickness of the product (sample) and the duration of exposure is based on material products, the expected hardness and thickness of the product in place of measuring the hardness in compliance with the conditions in accordance with table 1.

Table 1

2.6. For metals with a hardness on the Brinell hardness 343 MPa (35 kgf/mm) distance from center of the print to the edge of the sample should be at least 2.5 times the diameter of the imprint, and the distance between the centers of two adjacent prints must be at least four diameters of the print.

For metals with a hardness on the Brinell hardness 343 MPa (35 kgf/mm) distance from center of the print to the edge of the sample should not be less than three diameters of the fingerprint, and the distance between the centers of two adjacent prints must be at least six diameters of the print.

2.7. When measuring hardness on the products (samples) with a convex cylindrical surface, the minimum radius of curvature of the product (the sample) must be at least five diameters of the ball. In this case, the test may be carried out without the preparation of a flat surface.

When measuring hardness on the products (samples) with a convex cylindrical surface whose radius of curvature less than five times the diameter of the ball, width and length prepared flat surface must conform with the indentation of the ball of 2.5 mm diameter — not less than 5 mm, and the pressed in ball with a diameter of 1 mm at least 2 mm.

3. CONTROL

3.1. When measuring hardness by the Brinell ball is pressed into the surface of the product (specimen) test load applied for a certain time.

3.2. After the removal of the load is carried out measurement of the indentation diameter.

Indentation diameter must be measured in two mutually perpendicular directions and determine as the arithmetic mean of these measurements.

The difference between the measurements of the diameters of the prints must not exceed 2% of the smaller of them.

For anisotropic materials and products with convex cylindrical surfaces difference measurement of the diameters of the imprint must be specified in normative and technical documentation for metal products.

3.3. Brinell hardness number is defined as the arithmetic mean of results of three indentations caused.

4. PROCESSING OF THE RESULTS

4.1. Hardness Brinell hardness , MPa (kgs/mm), is determined by the table of hardness during indentation of a sphere with a diameter of 2.5 and 1 mm, are given in Appendix 1, or is calculated by the formula

,

where is the test load, kgf;

 — diameter of ball, mm;

 — indentation diameter, mm.

4.2. When measuring the hardness designation is complemented by indices indicating the measurement conditions in the following order: the first number before indicates the hardness in MPa (kgf/mm), after the first number indicates the diameter of the ball in millimeters, the second is the load in N (kgf) and the third dwell time under load in seconds. For example: 3000 2,5/1838,7/10 means Brinell hardness number equal to 3000 MPa, when tested ball with a diameter of 2.5 mm, under a load 1838,7 N, upon exposure for 10 s.

When testing for hardness of a ball of tungsten carbide designation is supplemented with letter with the preservation of these indexes.

4.3. The hardness values on the Brinell hardness to determine the tensile strength under tension in the test area.

The relationship between Brinell hardness and temporary resistance for structural carbon steels pearlitic class in the test ball with a diameter of 2.5 mm is given in Appendix 2. The determination error is ±5%.

ANNEX 1 (mandatory). Hardness on the Brinell hardness during indentation of a sphere with a diameter of 2.5 mm and 1

ANNEX 1
Mandatory

APPENDIX 2 (recommended)

ANNEX 2
Recommended

The electronic text of the document
prepared by JSC «Code» and checked by:
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M.: IPK Publishing house of standards, 2003