STUDIES IN THE CASTING OF AA6111 STRIP ON A HORIZONTAL, SINGLE BELT, STRIP CASTING SIMULATOR

摘要

Strips of AA6111 automotive alloy were cast on a horizontal single belt strip-casting simulator. Chill substrates of pure copper and carbon steel were sprayed with various coatings for improving the strips' surface quality. Experimental studies revealed that a graphite coating provided the greatest benefit in achieving good surface quality. Temperature variations within the moving mould were measured using thermocouples embedded at various depths and positions within the chill mould, and interfacial heat fluxes thereby calculated using the IHCP method (Inverse Heat Conduction Problem). Temperature variations and cooling rates within the strips themselves could then be calculated through numerical simulations based on the time-dependent heat fluxes obtained by the IHCP. The microstructures of the strip samples were studied by optical microscopy and by Scanning Electron Microscopy (SEM). The effects of casting parameters, including casting temperature and strip thickness, on interfacial heat fluxes, cooling rates and microstructures, were investigated. Very fine equi-axed grains were obtained for 1.2mm ～ 3.0mm thick strips thanks to the rapid extraction of heat, and effective grain refinement procedures.