Numerical simulations of solidification and hot tearing for continuous casting of duplex stainless steel
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ORIGINL PAPER
Numerical simulations of solidification and hot tearing for continuous casting of duplex stainless steel Shan-shan Liu1,2 • Liang Bai3,4 • Bo Wang1,2 Jie-yu Zhang1,2
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Yu Yao1,2 • Jun-kai Huang1,2 • Zheng Chen1,2
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Received: 26 March 2019 / Revised: 18 August 2019 / Accepted: 27 August 2019 China Iron and Steel Research Institute Group 2020
Abstract Hot tearing is one of the major defects in continuous casting of steels, which severely limits the productivity of steelmaking processes. To further understand the defect, the problem of hot tearing in duplex stainless steel produced by a vertical continuous caster was investigated. A three-dimensional heat transfer and elastic–plastic model was developed based on the realistic roller layout in continuous slab casting, using ProCAST software. According to the hot tearing indicator criterion, the influence of operating parameters on the hot tearing susceptibility was evaluated. The results show that the surface temperature distribution is not sensitive to the superheat. The center of wide surface shell at the mold exit is the thinnest, and the thickness is about 10.52 mm at the superheat temperature of 40 C. The hot tearing mainly concentrates on the slab solidification front and near the narrow face. However, corner cracks are prone to appear near the corner. With the increase in casting speed and the decrease in the cooling intensity in the secondary cooling zone, the solidification end point is rushed, which leads to the position of hot tearing lowering accordingly. Keywords Hot tearing Duplex stainless steel Numerical simulation Solidification Continuous casting
1 Introduction In the process of continuous casting, crack defect has been a perennial problem [1]. Hot tearing, occurring during solidification, is a serious problem in continuous casting of steels, which leads to sub-surface and surface cracking and, in the worst case, ending up in a shell breakout [2, 3]. Thus, productivity is severely limited and equipment damage significantly increases by this type of defect. The generation of hot tearing is related to many complex factors such & Bo Wang [email protected] 1
State Key Laboratory of Advanced Special Steel, Shanghai University, Shanghai 200072, China
2
School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China
3
Inner Mongolia Key Laboratory of Graphite and Graphene for Energy Storage and Coating, Huhhot 010051, Inner Mongolia, China
4
Inner Mongolia University of Technology, Huhhot 010051, Inner Mongolia, China
as equipment condition, solidification, cooling regime, and process operation. Due to the complex action of mechanisms during solidification, prediction of hot tearing phenomenon is a difficult task for researchers. In order to eliminate hot tearing in slab, it is necessary to take into consideration the industrial conditions of the continuous casting process [4]. Duplex stainless steels (DSSs) present a two-phase microstructure, ferrite
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