Effect of alloying elements on zinc-induced liquid metal embrittlement in steels: A first-principles study

Abstract

Liquid metal embrittlement (LME) induced by Zn melt in galvanized steels during spot-welding poses a significant challenge to the advancement of the automotive industry. A critical strategy to address this challenge is identifying promising alloying elements capable of mitigating LME. High-throughput first-principles calculations were employed to investigate the segregation behavior of 22 common alloying elements at the Σ5(310) grain boundary of iron and their impact on the grain boundary energy. The results indicate that volume distortion upon doping of the alloying elements predominantly influences their segregation behavior, while the weak bonding between Zn and Fe is responsible for the grain boundary embrittlement. Exploration of solute interaction between Zn and the other alloying element in the Fe grain boundary model reveals that the attraction between metallic doping elements and Zn correlates with both the elastic effects and the magnetic properties of the dopant, while the repulsion between non-metallic elements and Zn is primarily governed by the elastic effects. Separating the grain boundary strengthening energy into mechanical and chemical contributions shows that they correlate linearly with variations in volume of the doping site and changes in bond energy for bonds associated with the doping site at the grain boundary, respectively. Accordingly, the strengthening effect of the doping elements can be estimated by evaluating the induced changes in local volume and bond energies on grain boundaries. Furthermore, potential alloying elements to mitigate the Zn-induced LME are screened and discussed, with B and Mo being the most promising candidates.