Control of heat transfer and growth uniformity of solidifying copper shells through substrate temperature

Abstract

To determine the optimal roll temperature in a twin-roll copper-strip caster, copper blocks preheated between 25 ЊC and 350 ЊC were immersed in a bath of molten copper for 0.5 seconds. A significant increase in the contact heat-transfer coefficient at the substrate-shell interface was obtained when the substrates were heated above 200 ЊC and the gain in the solidified shell thickness was 20 pct. The shell growth was also approximately 35 pct more uniform at a high substrate temperature, and micrographic examination showed the dendritic structure to be finer. The contact heat-transfer coefficient was decomposed into two constituents, one for the substrate and the other for the shell. The former was found to be the limiting factor in heat transfer.

Dynamic wetting and heat transfer at the initiation of aluminum solidification on copper substrates

“…This arrangement was semi-intrinsic as the substrate acted as one element of the circuit [24,25,36]. Two such thermocouples were used in the tests, one at a depth of approximately 1 mm from the surface, the other at 5 mm, the exact location being measured to a precision of 0.01 mm with a vernier prior to an experimental run.…”

A Qualitative Study of the Influence of Grooved Mold Surface Topography on the Formation of Surface Marks on As-Cast Ingots of Aluminum Alloy 3003

“…For example, Murakami et al [34] reported 10% -30% increase in heat flux in the first 5 seconds of the solidification of hypoperitectic steel on a water-cooled chill with 1 -5 mm spaced vertical grooves compared to that on a smooth copper mold. Bouchard et al [27] [28] reported even higher increase in heat flux obtained in the early stages (<0.5 s) of solidification of a copper alloy on a water-cooled sand blasted copper chills and copper chills with 0.5 -2 mm deep vertical grooves with 0.15 -1 mm spacing. This suggests that the observed alleviation of surface lap marks with grooved mold surface topography is not entirely due to moderation of interfacial heat transfer.…”