Effects of Mn and Si on the ferrite decarburization of spring steel

Using a combination of experiments and first-principles calculations, we systematically investigated the influence of Mn and Si on the ferrite decarburization process in spring steel. The experimental findings demonstrated that the presence of Mn inhibited the ferrite decarburization of spring steel, and this inhibition effect was further enhanced when Mn and Si were mixed. The calculation results revealed the following insights: (1) In α-Fe, the interactions between Mn and neighboring carbon atoms were primarily weakly mutually attractive, while the interaction between Si and neighboring carbon atoms changed from repulsion to weak attraction with increasing distance. (2) The introduction of Mn raised the energy barrier for the outward diffusion of the carbon in α-Fe, thereby impeding its diffusion. (3) The coexistence of Mn and Si in α-Fe to formed an Mn–Si pair, resulting in a more pronounced inhibition of the outward diffusion of the carbon. These results significantly contribute to a deeper understanding of how alloying elements influence the decarburization process in steels and shed light on potential strategies for optimizing this aspect in steel production.