The re-solution of inclusions in remelted stainless steels

As a follow-up to work done on the remelting of three grades of 300 series stainless steels on a small scale electroslag remelting unit, adjunct studies were made on the kinetics of inclusion re-solution during the “electrode stage” of remelting. The objective of this study was to attempt to quantify the metallographic observations of many investigators that vary-ing degrees of inclusion re-solution do take place during the consumable remelting of numer-ous grades of metals and alloys. In specific, the rate(s)of re-solution of the large stringer inclusions found in the 300 series air melt stock was investigated. A known and controlled temperature gradient was imposed on long cylindrical specimens for varying times and, by a metallographic inclusion sizing and counting technique described in this paper, a series of isochronal and isothermal data was generated. Plots of rates of re-solutionvs time indi-cated a zero-order reaction mechanism and the activation energy calculated from the mea-sured reaction rate constants was found to be 36,000 J/mole. C. F. CHAN, J. W. GUERARD, and D. MILLER were all Seniors in the Metallurgical Engineering Department, at Queen’s University, Kingston, Ontario, when this work was done.