Coupled Thermo-Metallurgical-Mechanical Finite Element Modeling of Cooling Processes of Continuously Cast Slabs: Influence of Steel Grades and Process Conditions on Stress Evolution

As a key process subsequent to continuous casting, the cooling of cast slabs is of central importance for achieving desirably low internal stresses, thereby minimizing the risk of crack formation and structural breakage. Although the primary and secondary cooling process in continuous casting are well-established in research, studies on the thermo-metallurgical-mechanical phenomena during slab yard cooling remain critically limited. In this work, a coupled thermo-metallurgical-mechanical model is presented that elucidates the process of slab cooling, addressing the combined effects of specific alloys and cooling conditions. Three universal stages of stress accumulation are identified: the pre-transformation stage (1), the transformation stage (2), and the post-transformation stage (3). Specifically, the early ferrite transformation—which is key to many concepts of cracking susceptibility—is carefully analyzed. While stress accumulation in the transformation stage is substantially driven by the intrinsic material physics, it is shown that the potential for reducing room-temperature residual stresses resides in the application of innovative process designs in the post-transformation stage. Accordingly, a stress reduction of 50% can be achieved in critical locations. The developed model represents a versatile tool for process design and optimization, thereby contributing to the production of advanced, next-generation high-strength steels.