J. Mater. Sci. Technol. ›› 2023, Vol. 134: 163-177.DOI: 10.1016/j.jmst.2022.06.042

• Research Article • Previous Articles     Next Articles

Generalized stability criterion for controlling solidification segregation upon twin-roll casting

Pan Wua, Yubing Zhanga, Jiaqi Hua, Shaojie Songa,*(), Yong Lic, Huiyuan Wangd, Guo Yuanc, Zhaodong Wangc, Shizhong Weie, Feng Liua,b,*()   

  1. aState Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China
    bAnalytical and Testing Center, Northwestern Polytechnical University, Xi’an 710072, China
    cState Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, China
    dState Key Laboratory of Super hard Materials, Jilin University, Changchun 130012, China
    eNational Joint Engineering Research Center for Abrasion Control and Molding of Metal Materials, Henan University of Science and Technology, Luoyang 471003, China
  • Received:2022-05-18 Revised:2022-06-27 Accepted:2022-06-29 Published:2023-01-20 Online:2023-01-10
  • Contact: Shaojie Song,Feng Liu
  • About author:liufeng@nwpu.edu.cn (F. Liu).
    * State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China. E-mail addresses: sjsong@nwpu.edu.cn (S. Song),

Abstract:

Macro- and micro-segregation formed upon twin-roll casting (TRC) can be inherited from sub-rapid solidification to solid-state transformation, even to plastic deformation, thus deteriorating drastically mechanical properties of as-produced thin sheets. Although many works focusing mainly on controlling fields of thermal, concentration and convection have been reported, how to control artificially and quantitatively the segregation using a theoretical connection between processing parameters and solidification models, has not been realized, yet. Regarding it, a systematical framework integrating non-equilibrium dendritic growth and overall solidification kinetics with the TRC parameters, was constructed applying a generalized stability (GS) conception deduced from transient thermodynamic driving force ΔGt and transient kinetic energy barrier $Q_{\text{eff}}^{\text{t}}$ evolving upon solidification. Departing from this framework considering synergy of thermodynamics and kinetics (i.e., thermo-kinetic synergy), a criterion of high ΔGt-high GS guaranteed that the macro (i.e., the centerline) and the micro (i.e., the edge) segregation can be suppressed by increasing ΔGt and GS at the beginning and the ending stage of sub-rapid solidification, respectively. This typical thermo-kinetic combination producing the microstructure can be inherited into the plastic deformation, as reflected by corresponding strength-ductility combinations. This work realized quantitative controlling of TRC by a theoretical connection between processing parameters and solidification models, where, an optimization for sub-rapid solidification segregation using the GS conception including ΔGt and $Q_{\text{eff}}^{\text{t}}$ has been performed.

Key words: Segregation, Sub-rapid solidification, Generalized stability, Twin-roll casting, Thermo-kinetics