THE RELATION BETWEEN EXPERIMENTS AND MODELING OF RAPIDLY SOLIDIFIED 12CR-MO-V STAINLESS-STEEL

Solidification during melt spinning of a 12Cr-Mo-V stainless steel has been experimentally studied and numerically simulated. The resulting microstructures have been related to the unknown parameter h, i.e. the heat transfer coefficient between the substrate and the melt, by fitt ing the heat flow calculations and a phase selection model for a multi component system to the observed microstructures. Using the estimated value of the heat transfer coefficient, it was then possible to explai n the observed structures in terms of growth velocities. High growth v elocities (> 0.2 m s(-1)) resulted in formation of metastable austenit e as the primary phase near the chill side of the ribbon. Upon quenchi ng to room temperature, this austenite transformed into martensite. At a distance of about 15 mu m from the chill surface, the growth veloci ty of the solid/liquid interface decreased (< 0.2 m s(-1)), allowing t he stable ferrite phase to form as the primary phase. This approach pr ovides a means to determine the solidification parameters and the micr ostructures formed in this rapid solidification process. (C) 1998 Else vier Science S.A. All rights reserved.