BS ISO 18203:2016 pdf free
BS ISO 18203:2016 pdf free.Steel一Determination of the thickness of surface-hardened layers
Cut specimens for preparation with the gentlest possible technique, using only laboratory equipment.Mount specimens with a high-quality resin designed to provide excellent edge retention. Grind and polish using a proper sequence of abrasives to remove the damage from sectioning and grinding while maintaining edge retention. Exercise care to ensure that the region of interest is not altered by the sample preparation. The lower the test load in hardness testing, the higher the preparation quality must be. After polishing, etch the specimen with an appropriate solution to determine if the preparation was adequate and to see if there is a modification to the surface. Repeat one or more of the final preparation steps, if the quality is inadequate. Carefully clean off any films or residue on the surface. Do not touch the surface with fingers. For microindentation hardness testing, it is recommended to test an as-polished,non-etched surface. For the micrographic method, use the appropriate etch to reveal and discriminate between the different constituents present.
The centre of the first impression shall be at a distance, d1, from the surface of at least 2,5 times its diagonal.
Tests using Vickers or Knoop indents are performed at forces from 0,980 7 N to 9,807 N. Measurements of the impressions shall be made with a high quality light optical microscope and proper illumination,with or without a camera system (and possible by image analysis), at a high enough magnification so that the diagonals are between 25 % and 75 % of the eyepiece or screen width or height and the indent tips can be focused without distortion.
NOTE Due to the spacing of indents shown in Figure 3, test forces of 0,980 7 N to 2,942 N are normally used for this work.
Make the measurements on the prepared surface in two or more bands, the location of which shall be agreed between the parties concerned, and for each band plot the results in order to obtain the curve representing the variations in hardness as a function of distance from the surface. BS ISO 18203 pdf free.
