“Birth is much, but breeding is more” However, in the appraisal of tool steels, “virginities” of raw materials are respected as of old. The roles of impurities suspected have been investigated empirically, but the understanding of behavior of imprities, for example, segregation in grain boundaries and intefacial boundaries, is still incomplete. Advanced micro-chemical analysis techniques based on electron microscoptics are expected to overcome the mystery of roles of impurities in tool steels. Some of experimental data for this purpose carried out by means of AES are presented in this review.
