ISO 6507-1:2018 download free.Metallic materias – Vickers hardness test Part 1 : Test method.
The Vickers hardness test is specified in this document for lengths of indentation diagonals between 0,020 mm and 1,400 mm. Using this method to determine Vickers hardness from smaller indentations is outside the scope of ISO 6507-1 as results would suffer from large uncertainties due to the limitations of optical measurement and imperfections in tip geometry.
A periodic verification method is specified for routine checking of the testrng machine in service by the user.
For specific materials and/or products, particular International Standards exist.
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 ISO 6507-1. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 6507-2:2017, Metallic materials — Vickers hardness rest — Part 2: Verification and calibration of testing machines
ISO 6507-3, Metallic materials — Vickers hardness test — Part 3: Calibration of reference blocks
3 Terms and definitions
No terms and definitions are listed in ISO 6507-1.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
7 Test piece
7.1 Test surface
The test shall be carried out on a surtace wnicn is smooth and even, tree trom oxiae scale, roreign matter and, in particular, completely free from lubricants, unless otherwise specified in product standards. The finish of the surface shall permit accurate determination of the diagonal length of the indentation.
For hardmetal samples, the thickness of the layer removed from the surface shall be not less than 0,2 mm.
7.2 Preparation
Surface preparation shall be carried out in such a way as to prevent surface damage or alteration of the surface hardness due to excessive heating or cold-working.
Due to the small depth of Vickers microhardness indentations, it is essential that special precautions be taken during preparation. It is recommended to use a polishing/electropolishing process which is suitable for the material to be measured.
7.3 Thickness
The thickness of the test piece or of the layer under test shall be at least 1.5 times the diagonal length of the indentation as defined in Annex A. No deformation shall be visible at the back of the test piece after the test.
The thickness of a hardmetal test piece shall be at least 1 mm.
NOTE The depth of the indentation is approximately 1/7 of the diagonal length (0,143 d).
7.4 Tests on curved surfaces
For tests on curved surfaces, the corrections given in ThblesJJ. to l3..f shall be applied.
7.5 Support of unstable test pieces
For a test piece of small cross-section or of irregular shape, either a dedicated support should be used or it should be mounted in a similar manner to a metallographic micro-section in appropriate material so that it is adequately supported and does not move during the force application.
8 Procedure
8.1 Test temperature
The test Is normally carried out at ambient temperature within the limits of 10 °C to 35 °C. If the test Is carried out at a temperature outside this range, it shall be noted In the test report. Tests carried out under controlled conditions shall be made at a temperature of (23 ± 5) °C.
8.2 Test force
The test forces given in Table 4 are typical. Other test forces may be used including greater than 980,7 N, but not less than 0,009 807 N. Test forces shall be chosen that result in indentations with diagonals greater than 0,020 mm.
NOTE For hardmetals, the preferred test force is 294,2 N (HV 30).
Indentation should be made so that the diagonals are oriented In plane at approximately 450 to the direction of cold-working. The specification for the product could indicate limits for the differences between the lengths of the two diagonals.
8.5 Focus on test surface
The diagonal measuring system microscope shall be focused so that the specimen surface and the desired test location can be observed.
NOTE Some testing machines do not require that the microscope be Focused on the specimen surface.
8.6 Test force application
The indenter shall be brought Into contact with the test surface and the test force shall be applied in a direction perpendicular to the surface, without shock, vibration or overload, until the applied force attains the specified value. The time from the initial application of the Force until the full test force is reached shall be7 s.
NOTE I The requirements for the time durations are given with asymmetric limits. For esampLe. i! a
indicates that 7 s La the nominal Dma duration, with an acceptable range of not less than 2s (calcuLated as? a — S a)
to not more than 8 a (calculated as 7s + 1 a).
For the Vickers hardness range and low-force Vickers hardness range tests, the indenter shall contact the test piece at a velocity of sO.2 mm/s. For micro-hardness tests, the indenter shall contact the test piece at a velocity ofO,O7O mm/s.
The duration of the test force shall be i4i s, except for tests on materials whose timedependent properties would make this an unsuitable range. For these tests, this duration shall be specified as part of the hardness designation (see £2).
NOTE 2 There is evidence that some materials are sensitive to the rate o(straining which causes changes in the value of the yield strength. The corresponding effect on the termination of the formation ol an indentation can make aLterations In the hardness value.
8.7 Prevention of the effect of shock or vibration
Throughout the test, the testing machine shall be protected From shock or vibrationlSl.
8.8 MInimum dIstance between adjacent Indentations
The minimum distance between adjacent indentations and the minimum distance between an indentation and the edge of the test piece are shown in Figure.2.
The distance between the centre of any Indentation and the edge of the test piece shall be at least 2.5 times the mean diagonal length of the indentation in the case of steel. copper and copper allays and at least three times the mean diagonal length of the Indentation In the case of light metals, lead and tin and their alloys.
The 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 adacent indentations differ in size, the spacing shall be based on the mean diagonal length of the larger indentation.