Effect of Casting Roll Roughness on the Naturally Deposited Film and Its Related Heat Transfer During the Simulated Strip Casting of Hot-Stamping Steel

As a typical advanced high-strength steel, hot stamping steel is widely used in the automobile industry. Using strip casting to produce hot stamping steel can significantly reduce energy consumption and emissions, which aligns with the future development trend. This paper used the droplet solidification technique to study the effect of surface roughness of casting roll on deposited film, interfacial wettability, and its related interfacial heat transfer. The results revealed that the interfacial wettability becomes better with the formation of the deposited film. The film was formed with uniform particle size and distribution at low roughness; however, at high roughness, the film distribution was not uniform, especially the size of the film particles on the edge was significantly larger than that under the edge. Besides, the casting roll roughness greatly influenced interfacial heat transfer. The maximum heat flux values reached 9.8 MW/m² at the roughness of 5.3 μm, but only 3.8 MW/m² at the roughness of 30.7 μm. We recommend that in production, a low roll roughness should be used to guarantee uniform film deposition and obtain an appropriately deposited film thickness to ensure good interfacial heat transfer behavior.