6.1 The test shall be carried out on a surface which is smooth and even, free from oxide scale,
foreign 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.
6.2 Preparation shall be carried out in such a way that any alteration of the surface hardness, due to
heat or cold-working, for example, is minimized.
Due to the small depth of Vickers microhardness indentations, it is essential that special precautions
are taken during preparation. It is recommended to use a polishing/electropolishing process which is
suitable for the material parameters.
6.3 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 (see annex A).
No deformation shall be visible at the back of the test piece after the test.
6.4 For tests on curved surfaces, the corrections given in annex B, tables B.1 to B.6 shall be applied.
6.5 For test pieces of small cross-section or of irregular shape, it may be necessary to provide some
form of additional support.