Revealing mechanisms for significantly enhancing plasticity of high silicon steel by combining experiment with first principle

Abstract

Conventional high silicon steel possesses extremely low plasticity at room temperature, where even zero elongation can take place, so it is pretty difficult to implement cold working. In the present study, the novel Fe-6.5Si-2Cr-12Ni (wt%) high silicon steel is derived from addition of Cr and Ni, and in particular, Fe-6.5Si-2Cr-12Ni high silicon steel possesses much higher room-temperature plasticity than conventional high silicon steel and simultaneously it keeps very high tensile strength, where it possesses an elongation of 15.84% as well as an ultimate tensile strength of 1403.07 MPa at room temperature. An excellent combination of mechanical properties for Fe-6.5Si-2Cr-12Ni high silicon steel is attributed to refinement of grain, reduction of ordered phase, formation of acicular-ferrite-like lath structure and complexity of crystal orientation. The results calculated based on first principle are further responsible for the reason why Cr and Ni elements contribute to increasing plasticity of Fe-6.5Si-2Cr-12Ni high silicon steel, where 4s-orbital of Cr atom and 3d-orbital of Ni atom are directly involved in bonding. In particular, the activity of the electrons is increased and the intensity of metallic bond is enhanced, which is responsible for enhancing plasticity of Fe-6.5Si-2Cr-12Ni high silicon steel.