Instantaneous interfacial heat fluxes during the 4 to 8 m/min casting of carbon steels in a twin-roll caster

Abstract

Instantaneous heat fluxes between the roll and the solidifying metal were evaluated in a pilot twinroll caster, producing strips of low-carbon steels. This evaluation was based on the solution of an inverse heat-transfer problem, using temperature readings of thermocouples inserted at various locations in the roll sleeve. The response times of the thermocouples were determined and used to correct measured temperatures. The variation of the instantaneous heat fluxes with time of contact between the roll and the melt presented two distinct types of behavior, one exhibiting a single peak and other a double peak, depending on the casting conditions. These different patterns were interpreted in terms of the variation of the metallostatic pressure, solidification shrinkage, thermal expansion of the rolls, and characteristics of the solid shell. Predictions of the amounts of heat extracted by the roll and secondary dendrite arm spacings (SDAS) in the strips, based on the calculated heat fluxes, were in reasonable agreement with experimental values. This also demonstrated that the level of correction applied to the thermocouple readings was appropriate.

Numerical Simulation of Thermal Field of Work Roll during Top Side-pouring Twin-roll Casting of Steel

“…And the relationship between the curve shape and the rolling speed obtained in the simulation results partly confirmed the previous work of Tavares et al 10) in the TRC process.…”

“…Similar to the previous work of Tavares et al, 10) the second peak of the heat flux was observed in the simulation results, lower and wider than the first peak. According to the schematic of the TSTRC process, the second peak can be ascribed to the rolling pressure, corresponding to the location of solidification end close to the roll nip.…”

“…Compared to the experiments of Tavares et al 10) in the TRC process of low carbon steel, the similar relationship between the rolling speed and heat flux curves of roll-melt interfaces is found in the present work. Figure 4 shows the relationship between two peaks of heat flux curves with dif- ferent rolling speed.…”

“…Tavares et al 10) from Canada investigated the heat flux curves of roll-melt interface and the relationship between the curve shape and rolling speed in the TRC process of low carbon steel. When the rolling speed was low (4 m/min), the heat flux curves appeared single-peak.…”

Experimental Study of Interfacial Heat Flux and Surface Temperature by Inverse Analysis with Thermocouple (Fully Embedded) during Hot Steel Strip Rolling

“…Tavares et al (2001) [3] proposed an inverse method based on one-dimensional model (Lagrangian coordinate system moving at the same speed as the roll). The response time of the thermocouple is studied and a proper correction of the temperature data is introduced.…”