Numerical modelling and experimental casting of 17%Mn–4%Al–3%Si–0.45%C wt-% TWIP steel via the horizontal single belt casting (HSBC) process

Abstract

This paper presents optimum operating parameters for the production of thin strips of 40 mm in width and ∼4 mm in thickness of Fe-17%Mn-4%Al-3%Si-0.45%C wt-% TWIP (TWinning Induced Plasticity) steel using the present version of the Horizontal Single Belt Casting (HSBC) process. A two-dimensional model was developed to examine the flow of molten metal in the HSBC process, primarily focusing on investigating the instabilities/turbulence that arises when molten metal encounters the moving belt. For computational fluid dynamics modelling, three belt speeds were tested, i.e. 0.4, 0.8 and 1.2 (m s −1 ), against a constant molten metal velocity of 0.8 m s −1 at the nozzle slot outlet. It was observed that the molten metal/air interface fluctuations were appreciably suppressed/reduced when the belt and molten metal velocities approached each other. The fluctuations formed are damped further downstream, and any remaining surface perturbations can be eliminated via hot plastic deformation. An appropriate heat treatment was also designed for the TWIP steel strips, in order to achieve the desired microstructure and mechanical properties.

Numerical Modeling of Transport Phenomena in the Horizontal Single Belt Casting (HSBC) Process for the Production of AA6111 Aluminum Alloy Strip

“…As explained above, excessive backflow of molten metal into the quadruple region is not desired. This can be conveniently prevented by employing a double-impingement feeding system in the HSBC process [14]. In a double impingement feeding system the molten metal dispensing from the refractory nozzle slot first interacts with a 45 • inclined refractory plane, followed by its second interaction with the moving belt, on to which it begins to solidify [14].…”

“…This can be conveniently prevented by employing a double-impingement feeding system in the HSBC process [14]. In a double impingement feeding system the molten metal dispensing from the refractory nozzle slot first interacts with a 45 • inclined refractory plane, followed by its second interaction with the moving belt, on to which it begins to solidify [14]. In this way, the final impact of the molten metal with the moving belt is not as rapid and abrupt, as it would be for a single-impingement feeding system [4].…”

“…In this way, any molten metal surface discontinuities had enough time to settle down by the damping forces generated, before final solidification. The hydraulic jump on the inclined refractory plane could substantially degrade the surface quality of the cast product, owing to the generation of free surface waves/discontinuities [14]. As per the numerical simulations, the temperature over of the melt/air interface is above the liquidus for a considerable distance, as shown in Figures 11 and 12, even when considering perfect contact of molten metal with the moving belt, which is held constant at 300 K, by the cooling water under the belt.…”

“…Depending on the metal head in the launder, the velocity of the molten metal issuing from the slot nozzle can be easily adjusted. However, the force of gravity is also equally responsible in further accelerating the molten metal before it contacts the moving belt, on which it solidifies [13][14][15]. The material produced via the HSBC process can then be processed downstream, by hot rolling, followed by cold rolling, as shown in Figure 1.…”