Sulfide Inclusions in Electroslag Remelted Steels

摘要

The relationships among heat treatment, sulfide inclusion distribution and chemistry were investigated in this work, and the problem of overheating found to be directly related to these parameters. A basis for comparison was found in microscopic examination of carbon extraction replicas from commercially produced electroslag remelted steel. This showed a direct correlation between sulfide inclusion distribution and overheating. Further investigation characterized a critical cooling rate necessary for overheating to occur. Methods for eliminating the problem of sulfide inclusions in ESR steels were examined in detail. The simplest is to alter the cooling rate through the overheating range. Either a fast or a very slow cool eliminates the problem. An alternate method of eliminating the problem is to change the chemistry of the steel. These different compositions were examined in this work. All three were tested and proved to be successful in eliminating the sulfide problem. In an associated study a model to simulate the diffusion controlled coarsening and dissolution kinetics of particles within a metallic matrix was formulated. Calculations were made and compared with experiments in a model system and on manganese sulfide inclusions in iron. The effect of composition of manganese and of sulfur content was studied. Agreement of calculations is good. (Author)