GOST R ISO 4545-1-2015

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  ГОСТ Р ИСО 4545-1-2015

GOST R ISO 4545−1-2015 Materials metal. Determination of hardness Knopw. Part 1. Test method

GOST R ISO 4545−1-2015

NATIONAL STANDARD OF THE RUSSIAN FEDERATION

MATERIALS METAL

Determination of hardness Knopw

Part 1

Test method

Metallic materials. Knoop hardness test. Part 1. Test method

OKS 77.040.10
AXTU 0709

Date of introduction 2016−01−01

Preface

1 PREPARED by the Federal state unitary enterprise «Central research Institute of ferrous metallurgy them.And.P.Bardeen"

2 SUBMITTED by the Technical Committee for standardization TC 145 «monitoring Methods of steel products» on the basis of authentic translation into the Russian language the English language version of the standard specified in paragraph 4

3 APPROVED AND put INTO EFFECT by the Federal Agency for technical regulation and Metrology of April 9, 2015 N 248-St

4 this standard is identical to international standard ISO 4545−1:2005* «metal Materials. Determination of hardness Knopw. Part 1. Test method (ISO 4545−1:2005 «Metallic materials — Knoop hardness test — Part 1: Test method»).
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* Access to international and foreign documents referred to here and hereinafter, can be obtained by clicking on the link to the site shop.cntd.ru. — Note the manufacturer’s database.


In applying this standard it is recommended to use instead of the referenced international standards corresponding national standards of the Russian Federation and interstate standards, details of which are given in Appendix YES

5 INTRODUCED FOR THE FIRST TIME

Application rules of this standard are established in GOST R 1.0−2012 (section 8). Information about the changes to this standard is published in the annual (as of January 1 of the current year) reference index «National standards» and the official text changes and amendments — in monthly information index «National standards». In case of revision (replacement) or cancellation of this standard a notification will be published in the upcoming issue of the monthly information index «National standards». Relevant information, notification and lyrics are also posted in the information system of General use — on the official website of the Federal Agency for technical regulation and Metrology on the Internet (www.gost.ru)

1 Scope

This standard specifies a method for determining hardness of metallic materials by Kopu under load from 0,09807 to 19,614 N. Method is used for prints with a diagonal of less than 0,020 mm.

2 Normative references

This standard uses the regulatory references to the following international standards*:
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* The table of conformity of national standards international see the link. — Note the manufacturer’s database.

ISO 4545−2:2005 metallic Materials. Determination of hardness Knopw. Part 2. Verification and calibration of testing machines (ISO 4545−2:2005, Metallic materials — Knoop hardness test — Part 2: Verification and calibration of testing machines)

ISO 4545−3:2005 metallic Materials. Determination of hardness Knopw. Part 3. Calibration of reference blocks (ISO 4545−3:2005, Metallic materials — Knoop hardness test — Part 3: Calibration of reference blocks)

ISO 4545−4:2005 metallic Materials. Determination of hardness Knopw. Part 4. Table of hardness values (ISO 4545−4, Metallic materials — Knoop hardness test — Part 4: Table of hardness values)

3 the essence of the method

The essence of the method lies in the indentation of a diamond tip in the form of a pyramid with angles and between opposite sides equal to 172,5° and 130°, respectively, in the surface of the test sample under the action of applied loads (statistical* force) F (figures 1 and 2) and after removing the measurement of the length of the longest diagonal d of the imprint left on the sample surface.
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* The text of the document matches the original. — Note the manufacturer’s database.


Hardness Knopw proportional to the private from dividing the load on the projected area of the imprint of the indenter, which is a rhombic base of the pyramid and has at the top the same with the indenter corners.

Figure 1 — measurement Principle and geometry of the tip (indenter)

Figure 1 — measurement Principle and geometry of the tip (indenter)

Figure 2 — the print View

Figure 2 — the print View

4 Definitions and designations

4.1 figure 3 and table 1 outlines the main denitions and notation used in the hardness measurement Knopw.

Example

Figure 3. Basic definitions and notation used in the hardness measurement Knopw

Figure 3

Table 1

5 Instrument

5.1 Hardness, which should provide some load from 0,098 to 19,614 N, in accordance with the requirements of ISO 4545−2.

5.2 a Diamond tip in the form of a pyramid with base in the form of a rhombus, as defined in ISO 4545−2.

5.3 Measuring system must comply with ISO 4545−2. The optical part of the measuring system should have appropriate lighting (ISO 4545−3, Appendix a).

Magnification of the optical system should allow to increase the apparent length of the diagonal by more than 25%, but the field of view of the microscope should not increase by more than 75%. The measuring system needs to measure the lengths of the diagonals in increments of 0.1 CMI.

Note — the proposed procedure for testing hardness by the user are given in Appendix A.

6 Preparation for testing

6.1 Test performed on the polished surface which is smooth and smooth, free from scale and foreign matter and, in particular, completely free from lubricants, unless otherwise specified in the standard for steel. Final surface finish must allow to accurately determine the length of the diagonal of the print.

6.2 surface Preparation is carried out so that any change in surface hardness due to excessive heat or cold working is minimized.

6.3 In connection with the small depth of imprint it is important to take special precautions during sample preparation. It is recommended to use the technique of polishing (electropolishing), adapted to the material to be tested.

6.4 it is Not allowed to visible deformation on the back surface of the samples.

6.5 For samples of small cross section or of irregular shape it is necessary to provide some additional support standard, such as shape, made of plastic, but it is important to ensure that the test sample does not move during application of the load.

7 testing

7.1 the hardness Measurement is carried out at a temperature of (23±5)°C. If the test is performed at another temperature, it should be noted in the test report.

7.2 Recommended test loads for testing are shown in table 2.

Table 2

7.3 the test sample should be placed on a rigid Foundation. The surface of the support must be clean, free from foreign substances (water, oil, dirt, etc.). The test sample should lie on the support in such a manner that it cannot be moving during the measurement.

7.4 Focus the measuring microscope must be placed so that it was possible to observe the surface of the sample.

7.5 During the test tip (indenter) is brought into contact with the surface of the test sample and increase the load in the direction perpendicular to the surface, without shock or vibration, until the applied load reaches a certain value.

The rate of application of force must be in the range of 15 to 70 µm/s.

Time from the start of application of the load to the rated load value should not exceed 10 seconds.

7.6 dwell time under load should be 10−15 C, unless otherwise noted. For some materials in order to obtain stable results provided a longer dwell time under load, the tolerance for the duration of the exposure in such cases shall be ±2 C.

7.7 throughout the test cycle, the tester should be protected from shock and vibration.

7.8 the Minimum distance between the boundary of any of the print and the edge of the specimen should be at least tripled the value of the length of the short diagonal of the print.

7.9 Minimum distance between two adjacent prints, oriented side-to-side, should be not less than 2.5 times the length of the short diagonal. The distance between two adjacent prints focused their ends, should not be less than the length of the long diagonal. If two prints differ in size, estimate the minimum distance is carried out diagonally larger print.

7.10 To calculate hardness Knopw use the measured length of long diagonal. For all tests the boundaries of the fingerprints should be clearly visible and identified in the field of view of the microscope.

Note — Reducing the test load leads to an increase in scatter of the measurement results. This is especially evident at low loads tests Knopw when measuring the length of the long diagonal. When measuring hardness Knopw measurement accuracy the length of the long diagonal is usually not better than ±0.001 mm. the Increase of the field of view of the microscope can lead to increased measurement precision by more than 25%, but increase the field of vision must be less than 75%.

7.11 the hardness Value at Knuppe is calculated by the formula given in table 1, or determined by the tables of ISO 4545−4.

7.12 If the measured values of the lengths of the long diagonals of one half of the prints differ by more than 10% from the measured values of the length of the other half of the prints, check the parallelism of the sample relative to the reference plane on which it is placed. Test results with deviations exceeding 10% do not.

8 Evaluation of uncertainty of measurement results

A complete evaluation of uncertainty of measurement results should be carried out in accordance with the requirements of the guide GUM [1].

Regardless of the sources affecting the uncertainty in the evaluation of hardness, for its evaluation, there are two methods:

— one method (type A) based on the assessment of uncertainty all potential sources that arise during the direct calibration of the load measuring system. The evaluation procedure presented in [2];

the other method (type b) based on the estimation of uncertainty using standard measures of hardness [abbreviated as CRM (certified reference material)] (see [3]-[5]). Guidelines for application are given in Appendix B.

However, it is not always possible only to quantify all the components of uncertainty from different sources. In this case, the estimate of the standard uncertainty of type A can be performed by statistical analysis of several prints produced on the test sample. In the case where the standard uncertainties obtained by type A and type b, are added, care should be taken not to consider components from a variety of sources twice ([1], section 4).

9 test report

The test report shall contain:

a) reference to this standard;

b) all the necessary information to identify the test sample;

c) the results obtained;

d) all operations not specified by this standard, which can be considered as additional;

e) information about any circumstances that could affect the results;

f) the temperature at which conducted the test, if it is outside the range specified in section 7.

Note — valid comparison of hardness values is only possible if there are identical values of the applied load.

Annex a (informative). Periodic check of test equipment by the user

Appendix A
(reference)

Verification of testing equipment (hardness tester) should be performed on the same day, when the equipment is used. Control every range or scale on which to conduct the measurement.

Inspection of hardness is carried out according to the measures of hardness (for each range and level of hardness). To do this, put the reference fingerprints in the reference measure of hardness, calibrated in accordance with ISO 4545−3. The measurement result should correspond to the certified value within the range not exceeding 0.5% and 0.4 microns. If the obtained values do not satisfy the requirements, you should take steps to resolve inconsistencies.

The check consists in obtaining a single print on the reference measure of hardness, calibrated in accordance with ISO 4543−3.* If the difference between average and certified values is within the tolerance given in ISO 4545−2 (paragraph 5.8), the hardness tester is ready to test. Otherwise, you should calibrate the hardness tester measures hardness.
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* The text of the document matches the original. — Note the manufacturer’s database.


The results obtained should be recorded within a certain period of time for evaluation of hardness and tracking drift settings.

Annex b (informative). The measurement uncertainty of hardness values

The App
(reference)

B. 1 General requirements

The method discussed in the present application, relates to the evaluation of uncertainty of measurement results associated with the measuring capabilities of the hardness during calibration of the standard measures of hardness (SRM). Calculated by the present method, the uncertainty reflects the combined effect of all sources of uncertainty, because under this approach individual components of hardness are within specified tolerances. It is recommended to check and calibrate at least once a year.

Figure V. 1 shows the four-level structure of the metrological chain of traceability to the definition and dissemination of hardness scales. The chain starts with the international level, using the international definitions of the various hardness scales to carry out international comparisons. The number of hardness primary standard at the national level, define the primary measures of hardness for the calibration of hardness testers in the laboratory level. Naturally, direct calibration and the verification of these machines should be carried out with maximum precision.

Figure B. 1 — structure of the metrological chain of traceability to the definition and dissemination of hardness scales

Figure B. 1 — structure of the metrological chain of traceability to the definition and dissemination of hardness scales

B. 2 the Basic procedure

The procedure for determining the combined uncertainty u performed by the square root of the sum of the squares of the indices calculated from various sources, are given in table B. 1. The expanded uncertainty U is determined by multiplyinguby a factor of scope k=2. Table B. 1 contains all symbols used and their definitions.

V. 3 deviation of the indicators of hardness of

The deviation of the indicators of hardness (often referred to as error), b get the difference between:

— average measurements of five prints produced in the process of testing hardness reference measure hardness, and

— the value assigned to the reference measure hardness when it is calibrated.

This deviation can be used in different cases of calculating uncertainty as amendments to the measurement result.

B. 4 algorithm for the calculation of uncertainties — measurement of hardness value

V. 4.1 Procedure, not taking into account the deviation of the indicator of the hardness (method 1)

Method 1 (M1) is the simplest method, which is used without considering the systematic error of the hardness tester.

In M1 the error is determined on the basis of the permissible error of the hardness tester relative to the theoretical scale, which is used to identify the source of uncertainty u. It does not specify the amendment to be paid.

The calculation procedure U described in table B. 1 and also in [1] and [2].

. (V. 1)

The measurement results can be represented as follows

. (V. 2)

V. 4.2 Procedure that takes into account deviations of the measure of hardness (method 2)

In contrast to method 1 (M1) method 2 (M2) results in lower values of uncertainty. In assessing method M2 is based on the fact that, since the deviation b(step 10) presumably in a systematic manner, in accordance with the recommendations of [1] should be amended to the result of measurement for correction of this error. Further assume that as the amendments identified and included in the measurement result, the calculation of the uncertainty of the systematic error considered equal to zero. Otherwise Uincreasing on b.

The calculation procedure Uare shown in table B. 1 and also in [4], [5].

. (V. 3)

The measurement result will be presented in the following form:

(V. 4)

or

. (V. 5)

Depending on whether to include the deviation of b as an amendment of the scale of hardness, use either one or the other expression for the results presentation.

B. 5 Expression of results of measurements

When the expression of uncertainty of measurement results should indicate the method of its determination. If the method is not specified, it is assumed that was used in method 1 (step 12, table V. 1).


Table B. 1 — Determination of expanded uncertainty in accordance with the methods M1 and M2

App YES (reference). Information about the compliance of the referenced international standards national standards of the Russian Federation (and acting in this capacity inter-state standards)

App YES
(reference)

Table YES.1

Bibliography

The electronic text of the document
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M.: STANDARTINFORM, 2015