Electro-slag remelting is an important process to produce high quality tool steels. Thereby the slag composition has a strong effect on the remelting behavior in general and on the electric energy consumption as well as on the removal of non-metallic inclusion. Later aspect is strongly related to chemical reactions taking place between the slag and the metal and thereby determines the necessary compositions of the slag. Also the electrical conductivity of the slag is determined by the slag composition, and a high resistivity, among other factors, is desirable to reduce energy consumption.
The effect of different slag compositions with a wide range of electrical conductivity was investigated regarding their general remelting behavior such as slag movement, slag surface temperature and slag skin thickness as well as their impact on chemical reactions and the removal of non-metallic inclusions. Therefore a laboratory scale ESR-unit, equipped with several measurement devices and a typical plastic mold steels were used for the experimental trials.
The results show a strong impact on the remelting behavior as well as on the specific energy consumption. Standard slags thereby show a good agreement with earlier reports form industrial scale results of a similar tool steels. The findings form the chemical analysis and detection of non-metallic inclusions indicate, that a similar metallurgical behavior is feasible despite large differences in the energy consumption.