Studies of interfacial heat transfer resistances and characterization of strip microstructures for Al-Mg alloys cast on a single belt casting simulator

Abstract

Interfacial heat transfer resistances during the solidification of aluminum-magnesium alloy strips were measured using the IHCP (Inverse Heat Conduction Problem) method. For these experiments, a small simulator of a single belt caster was used and interfacial heat fluxes and heat transfer coefficients were obtained assuming unidirectional heat flow. The influence of thermophysical properties of substrate, melt superheat and roughness of substrates on strip microstructures in the longitudinal and transverse directions were also investigated. Experimental studies revealed that low superheats (similar to2 degreesC) produced finer grain sizes (similar to40 mum) and homogeneous microstructures were obtained. High thermal conductivity substrates such as copper resulted in strips that were more uniform in thickness and had improved surface quality. It was also found that there was a critical substrate roughness which provided more nucleation sites at the metal/substrate interface resulting in a fine grain distribution throughout the strip produced.