One possible solution is to estimate the carbon content in the micrograph. The carbon content can be determined in small samples of low-alloy and unalloyed steels by microscopic examination of the carbide formation. This is of interest, for example, in the case of chips or fragments with a length of 0,1 - 10 mm, the origin of which needs to be narrowed down more precisely. The carbon content can be determined in the micrograph using image analysis via the ratio of ferrite to pearlite. This applies to steels with a carbon content of up to approx. 0,8%, since 100% pearlite is achieved in equilibrium.
For this purpose, the particles are directly cold embedded, ground, polished and contrasted in 3% alkaline HNO3 (Nital).
The pearlite content is then determined microscopically as a surface proportion using the entire chip surface.
This gives the carbon content in % = pearlite content x 0,8 %
The method is an estimate and not a measurement and is based on the steel-iron test sheet SEP 1520 (series of images on the C content) and was validated in GWP internal ring tests. This enables us to characterize steel particles even more precisely. In combination with EDX measurements and evaluation of the morphology, important clues are obtained for clarifying the origin of the particles, e.g. in the event of damage.
Do you have any questions about structural evaluations or do you need corresponding laboratory tests?
