Induction heating is a fast, consistent and easily controlled process used to bond, harden or soften metals. An important use is after welding, metalworking, heat treating or metal melting to restore ductility. Induction heating occurs when an electrically conducting object, usually metallic, is placed in an electomagnetic field.
One advantage of induction heating is that no torch or flame is applied directly to the metal parts; hence there is no product contamination. Another advantage is the precise control of the heat-treated zone which is needed for small parts such as those used in car manufacturing.
Traditional microhardness testing instruments
When testing for hardness, the machines used traditionally had only one particular function and that was to test the hardness of a given material or sample. However, in some cases the information generated by a single line of indents on a heat-treated sample is not enough. These traditional mircohardness testers cannot give valuable additional information such as the proportion of the heat-affected area compared to the total sample, or the average depth (layer thickness) of the heat-affected zone.
Image analysis software plus hardness testing, a winning combination
Using the automated Clemex CMT.HD tester as a microscope in combination with a flatbed scanner allows a more complete analysis. The system acquires an image of the sample that can then be used for both precise positioning and to easily analyze other aspects of the sample.
First, the sample is scanned in order to get a global view of the area to analyze and position the indent traverse. After execution and measurement of the series of Vickers indents, hardness values can be converted to the HRC scale. The image can then be binarized for area percent measurement (inner and outer zones compared to the total area) and thickness variation of the heat-affected zone.
Image analysis method for measuring the thickness of heat-affected zones in induction heated parts
Read the original article.