Effect of solutes on the performance of Zn-coating and Zn-inducing transgranular cracking in steel based on DFT calculations

Abstract

The effect of solutes, Co, Cu, Cr, Mn, Mo, Nb, Ni, Ta, Ti, V and Zr, in steel on the penetration properties of Zn and stability of surface or matrix were explored theoretically using density functional theory method, and the role of solutes in the Zn-coated surface and Zn-induced transgranular fracture performance was considered. The effect of solution on α-Fe are more obvious than that on γ-Fe, they significantly change surface energy value and the order of stability of low-index surface in α-Fe. The segregation energies of solutes were calculated and concluded that most of selected elements possibly segregate to the surface from the matrix. The study about Zn adsorption properties found that Zn atoms is energetically favorable to absorb at the (001) surface layer in α-Fe, and the segregation of Zr, V, Nb and Ta are helpful to the process of Zn-coating and increase the stability of Zn-coated surface. In addition, the solutes in the matrix increase the difficulty of transgranular fracture. Although the surrounding of solutes is the preference site for cracking occurring and propagation, alloying is found to lead to a general increase in the cleavage energy of α-Fe during Zn penetration, suggesting a reduction in the tendency for transgranular fracture. Therefore, it is feasible that the addition of Zr, V, Nb and Ta as alloy element in steel to improve the properties of Zn-coating and inhibit the occurrence of Zn-inducing transgranular cracking. Our results are helpful to understand and design AHSSs inhibiting LME susceptibility.

Keywords

• Density functional theory
• Segregation
• Zn-coated
• Zn-induced transgranular fracture