Finite Element Analysis of Dynamic Recrystallization of Casting Slabs during Hot-Core Heavy Reduction Rolling Process

Abstract

Hot-core heavy reduction rolling (HHR2) is an innovative technology, where a two-high rolling mill is installed after the solidification end of a strand, which can significantly eliminate the core defects of the slab. The mill exhibits a heavy reduction ratio, which promotes the dynamic recrystallization (DRX) of the slab. This study aims to optimize the parameters of the HHR2 process considering the effect of DRX on microstructure homogeneity. The secondary development of commercial software DEFORM-3D is conducted to calculate the deformation and DRX behavior of HHR2 for different reduction ratios. The parameters of DRX volume fraction and DRX grain size are compared, and finer DRX grains are obtained when the greater reduction ratios are conducted in HHR2. Then, corresponding to the deformation conditions in the HHR2, the thermal–mechanical simulations are conducted on the Gleeble3800 to obtain the average grain sizes before and after this process. When the reduction amount increases from 20 mm to 50 mm, the difference of average grain size between the core and the surface reduces by 52%. In other words, appropriately enhancing the reduction ratio is helpful to reduce the average austenite grain and promote the microstructure uniformity of the slab. These results provide some valuable information on the design of deformation parameters for HHR2.

Modular Finite Element Modeling of Heavy Plate Rolling Processes Using Customized Model Reduction Approaches

“…On the other hand, alternatives to conventional or variants of hot rolling processes are also being modeled and simulated. An interesting approach is a process presented as "Hot Core Heavy Reduction Rolling", the properties of which are discussed in [16][17][18][19] based on numerical and analytical studies and experimental data. In addition to simulating void healing in heavy plates, by deploying FE and phase-field simulation [20], the hot rolling of clad plates has also received increased attention recently, as numerical and experimental work shows [21][22][23].…”

Comparison of Dynamic Recrystallization in Blooms between Conventional Rolling and Hot‐Core Heavy Reduction Rolling Process

“…[14] On the other hand, the HHR 2 process can promote the dynamic recrystallization (DRX), which can obtain a better uniformity of microstructure comparing with the original casting slab. [15,16] Furthermore, the DRX behavior may be different from the conventional hot rolling (CHR) process because a greater deformation DOI: 10.1002/srin.202300043 Hot-core Heavy Reduction Rolling (HHR 2 ) is a new technology that improves the core quality of blooms by using a heavy reduction roller at the solidification end. Dynamic recrystallization (DRX) is expected to optimize the microstructure in this process.…”

“…[ 14 ] On the other hand, the HHR 2 process can promote the dynamic recrystallization (DRX), which can obtain a better uniformity of microstructure comparing with the original casting slab. [ 15,16 ] Furthermore, the DRX behavior may be different from the conventional hot rolling (CHR) process because a greater deformation permeability and a higher temperature are obtained in the bloom of HHR 2 process.…”

Influence of hot-core heavy reduction rolling on microstructure uniformity of casting billet

“…Thus based on the constitutive study of Nb-Ti micro-alloyed steel, the recrystallization grain size model was established by Gong et al [18]. While the microstructure of plates under and without HHR 2 was compared in terms of the average grain size by Li et al [19], and the impact of reduction ratio parameters on microstructure homogeneity was reported [20]. Nonetheless, the above studies do not demonstrate the process of grain size variation in the context of different HHR 2 processing, nor does it reveal the process in the complex case where there is a temperature gradient in the thickness direction of a billet, and third, the initial grain state formed by the casting process is not considered.…”