Quantitative assessment of segregates in continuously cast slabs by electron probe microanalysis

Due to the limited solubility of individual elements in the crystal lattice of steel, an enrichment of the residual melt and furthermore a formation of micro and macro segregates will appear during solidification of the steel melt. Depending on the chemical composition of the steel, the operation parameters of the casting plant and the slab dimension, the segregates will be formed with different intensities. The knowledge of the segregation effects is imperative for further processing of slabs and the subsequent products. The electron probe micro analyser (EPMA) makes feasible an objective assessment of the segregates due to solidification over the entire slab thickness. This is carried out by concentration mapping (CM), which is a method for the quantitative determination of element distributions over certain areas on the sample. In this paper some results taken from an investigation on steel grade 13 CrMo 4–5 are presented, and some casting technological measures derived from these results are proposed.