hardness test —. Part 1: Test method. Matériaux métalliques — Essai de dureté Vickers —. Partie 1: Méthode d’essai. STANDARD. ISO. Fourth edition. ISO INTERNATIONAL. STANDARD. ISO. Third edition. Metallic materials — Vickers hardness test —. Part 1: Test method. Matériaux . I.S. EN ISO is the adopted Irish version of the European . The text of ISO has been approved by CEN as EN ISO.
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Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO consists of the following parts, under the general title Metallic materials — Vickers hardness test: It is intended to make the annex normative in the next revision of this part of ISO Standard.
For automated measuring systems this standard should be applied accordingly. Test method 1 Scope This part of ISO specifies the Vickers hardness test method, for the three different ranges of test force for metallic materials see Table 1.
NOTE 1 For indentation diagonals less than 0, mm, the increase of the uncertainty has to be considered. NOTE 2 In general, decreasing the test force increases the scatter of results of the measurements. This is particularly true for low-force Vickers hardness tests and Vickers microhardness tests, where the principal limitation will arise in the measurement of the diagonals of the indentation. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document including any amendments applies. Figure 1 — Principle of the test The Vickers hardness is proportional to the quotient obtained by dividing the test force by the sloping area of the indentation, which is assumed to be a right pyramid with a square base, and having at the vertex the same angle as the indenter.
The finish of the surface shall permit accurate determination of the diagonal length of the indentation.
Due to the small depth of Vickers microhardness indentations, it is essential that special precautions are taken during preparation. No deformation shall be visible at the back of the test piece after the test. NOTE Other values e.
HV 2,5 24,52 N may be used. The support surfaces shall be clean and jso from foreign matter scale, oil, dirt, etc. It is important that the test piece lies firmly on the support so that displacement cannot occur during the test.
The time from the initial application of the force until the full test force is reached shall uso be less than 2 s nor greater than 8 s. For low-force hardness and microhardness tests, the maximum time shall not exceed 10 s.
The duration of the test force shall be 10 s to 15 s, except for tests on materials whose time-dependent properties would make this an unsuitable range. For these tests, a longer ieo is permitted and this duration shall be specified as part of the hardness designation see EXAMPLE in 4. Lso distance between the centres of two adjacent indentations shall be at least three times the mean diagonal length of the indentation in the case of steel, copper and copper alloys, and at least six times the mean diagonal length in the case of light metals, lead and tin and their alloys.
If two adjacent indentations differ in size, the spacing shall be based on the mean diagonal length of the larger indentation. The arithmetical mean of the two readings shall be taken for the calculation of the Vickers hardness. If the difference is greater, this shall be stated in the test report. Independent of the type of sources, for hardness there are two possibilities for ieo determination of the uncertainty.
As a reference, an EA guideline  is available. A guideline for the determination is given 6507- Annex D. It may not always be possible to quantify all the identified contributions to the uncertainty.
In this case, an estimate of type A standard uncertainty may be obtained from the statistical analysis of repeated indentations into the test piece. Care should be taken, if standard uncertainties of type A and B are summarised, that the contributions are not counted twice see Clause 4 of GUM: NOTE 1 Iiso strict comparison of hardness values is only possible at identical test forces.
There is no general process of accurately converting Vickers hardness into other scales of hardness or into tensile strength. Such conversions, therefore, should be avoided, 6507-11 a reliable basis for conversion can be obtained by comparison tests. It should be noted that for anisotropic materials, for example those which have been heavily cold-worked, there will be a difference between the lengths of the two diagonals of the indentation.
The specification for the product may indicate limits for the differences between the lengths of the two diagonals. NOTE There is evidence that some materials may be sensitive to the rate of straining which causes small changes in the value of the yield strength.
The corresponding effect on the termination of the formation of an indentation can make alterations in the hardness value. The required thickness is given by the point of intersection of the minimum thickness scale and a line shown dotted in the example in Figure A.
The correction factors are tabulated in terms of the ratio of the mean diagonal d of the indentation to the diameter D of the sphere. The correction factors are tabulated in terms of the ratio of the mean diagonal d of the indentation to the diameter D of the cylinder.
The measured dimension should agree with the certified value to within the maximum permissible error given in Table 5 of ISO If the measuring system fails this test, appropriate action should be taken.
The check involves at least one indentation being made on a hardness reference block, calibrated in accordance with ISO If not, an indirect verification should be performed. A record of these results should be maintained over a period of time, and used to measure reproducibility and monitor drift of the machine.
These performance uncertainties reflect the combined effect to all the separate uncertainties indirect verification. Because of this approach, it is important that the individual machine components are operating within the tolerances. It is strongly recommended that this procedure be applied for a maximum of one year after the successful passing of a direct verification. The chain starts at the international level using international definitions of the various hardness scales to carry out international intercomparisons.
Naturally, direct calibration and the verification of these machines should be at the highest possible accuracy. In M1, the error limit, that means the range in which the machine is allowed to differ from the reference standard is used to define the source uE of the uncertainty. There is no correction of the hardness values with respect to the error.
The procedure for the determination of U is explained in Table D. M2 may lead to smaller values of uncertainty.
The error b step 10 can be expected to be a systematic effect. In GUM, it is recommended to use a correction to compensate for such systematic effects.
This is the base of M2.
The error is no longer in the calculation of the uncertainty but all determined hardness values have to be corrected by b or Ucorr has to be increased by b. The procedure for the determination of Ucorr is explained in Table D. In general, as a result of the measurement, method 1 [Equation D. Verlag Berliner Union Stuttgart,pp Ihre Klassifizierung und Auswirkung auf die Messwerte.
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