Image analysis study of macrosegregation in a high-carbon continuously cast steel

By means of an automatic image analysis procedure, a description and quantification of the macrosegregation level in an AISI 4340 steel produced by continuous casting through different routes was carried out. As a comparison, the steel was also produced by conventional ingot metallurgy. For the metallographic observations, reference was made to the transverse sections with respect to the casting direction and then to the cross sections of the carbide streakings. Two parameters were introduced: the 95 percentile of the dimension of the segregated areas and the 95 percentile of the distances between two nearest segregated areas. The results of the investigation show that these parameters allow an accurate quantification of the segregation level. They can be conveniently represented on a map that can be supplied with “performance regions” after specific tests have been carried out.