Investigation on band segregate formation during the electroslag remelting of H13 die steel

Band segregation has been found in the H13 die steel produced by the electroslag remelting (ESR) technology. Chemical and metallographic studies have been carried out on a one ton ESR ingot of H13 die steel, so as to understand the formation mechanism of the band segregation. The results indicate that the T.O content and S content decreased because of cleanliness improvement of ESR process. Transverse macrosegregation of S content decreased after ESR. The overall removal ratio of the inclusion is around 65.8%. The original complex inclusions would be modified to the CaO•Al2O3 inclusions. Al2O3 and MnS inclusions can be found after ESR. Both of Al2O3 and MnS inclusions were found to be the core of primary carbides. The net like structure in ESR ingot and banded structure in the forged steel were observed. V, Mo, Cr and S are rich in the segregation areas of ESR ingot. Besides, black and white segregation bands can be observed on the forged steel samples after etching. Uneven distribution of carbides rich in V, Mo and Cr was observed in banded structure.