Morphology and precipitation kinetics of AlN in hot strip of low carbon steel produced by compact strip production

Morphology and precipitation kinetics of AlN were investigated both experimentally and using a predictive model in hot strip of low carbon steel produced by compact strip production (CSP), a process for the production of hot strip from a continuously cast thin slab using direct charging. By an electrolytic dissolution technique and TEM analysis, the shapes of AlN were cube or plate, the precipitates were uniform and very fine, with average size less than 8 nm. The paper presents a model to describe the precipitation kinetics of AlN under thermomechanical process conditions of CSP, which predicted volume fraction evolution and the precipitate size of strain induced precipitation on the basis of classical nucleation theory. For the process conditions of this paper, about 3 s time was sufficient for appreciable strain induced precipitation occurred immediately and entirely on dislocations after the sixth finishing rolling pass, and the computing radius of precipitate was 2 nm, which was in good agreement with experimental data. The differences of AlN precipitation between CSP and conventional process are also discussed. (C) 2002 Elsevier Science B.V. All rights reserved.