SynopsisFor new precise evaluation techniques of segregation in continuously cast steel, Macroanalyser and Computer-aided Micro-analyser were developed by R & D Laboratories-land -III of Nippon Steel Corp. These techniques, based on the analytical principle of an EPMA (an electron probe microanalyser), can present the spacious two-dimensional maps of the concentration of segregated elements such as Mn, P, C etc, and can offer the quantitative information on the fractions of segregated area and the size distribution of segregation spots corresponding to optional concentration of segregated elements. Therefore, these are useful enough to clarify the mechanism of segregation, the operational conditions for the control of the segregation and what factors of segregation are related to the quality of products.In addition to these quantitative methods, the segregation etch print technique, by which the segregation can be easily and rapidly detected and recorded in very wide area of the inspection surfaces of big specimens with an excellent resolving power even for low sulphur content steel or Ca added steel, has been developed by Yawata R & D Lab, of Nippon Steel Corp. and is now in use for the inspection of continuously cast slabs instead of the conventional methods like Baumann print.

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