Examinations to segregation distribution

Segregation structure over the cross-cut

Primary segregations arises during the solidification of the steel, at the transition of the phase from the liquid into the solid condition. There are to distinguish ingot segregation and crystal segregation. Ingot segregations arises because of a volume shrinkage at the solidification of a ingot. In front of the solidification accompanying elements and inclusions are pushed and were enriched in the rest of the cast. Crystal segregation are separations and arises at fast cooling, because then there is remaining no time for the concentration compensation. Microscopic concentration differences arises, because at solidification begin first such crystal precipitate which are low at accompanying elements such as phosphorus, sulphur and carbon. Only with a progressive solidification the amount of solidification share accumulates . The content of alloying elements increases from inside to the outside at the crystallite. Rest fields show the highest concentration in accompanying elements. The extent is certainly of being struggled by the size of solidification interval, the diffusion ability of the accompanying elements and the solidification conditions. Segregations can be proved with the microsample, by making a pickle test, by etching of microsections and by the making sulphur prints. Segregations impair a number of steel qualities.

The following links leads you to enlarged representations of the segregation distribution at different steel grades. It is continuous casting material which is rolled to round dimensions.
The magnification is, when not differently noted, 50:1 . The pictures have a additional magnification on dem screen from ca. 40 % (refered on 17" screen at 1024 x 768 Pixel). If there is a modem connection you have to calculate longer times for loading, because the represented pictures have shown a size of ca. 200 - 600 Kbyte. No stronger compression of the photos could be carried to ensure an image quality as high as possible. The pictures represent only a choice of possible crystalline structures and segregation distributions at different heat treatment conditions. The segregation distribution is dependent on different factors which positively or negatively influence the form. This factors are casting temperature, casting rate, stirring parameter and cooling rate.

Segregation structures at different materials

1.5510 - 28 B 2 spheroidised 11,50 mm