Study of the Mechanism Influencing the Initial Corrosion Behaviour of B2 Phase Fe-Mn-Al-C-Ni Lightweight Steels in 3.5% NaCl Solution

In recent years, lightweight steels have become a hot research topic in the field of materials. However, little research has been done on the corrosion resistance, which is of great significance to the service life of the alloy. In this paper, the initial corrosion behaviour of Fe-Mn-Al-C-Ni lightweight steels with different B2-phase grain sizes in 3.5 wt.% NaCl solution was investigated. The immersion corrosion process of Fe-Mn-Al-C-Ni mild steel and the selective corrosion characteristics of the alloy surface were revealed by quasi-in-situ short-period immersion tests and electrochemical experiments. As a result, the grain size of the granular B2 phase is significantly reduced compared with that of the striped B2 phase, and the granular B2 phase is diffusely distributed in the matrix, which makes the corrosion tend to be uniform and improves the corrosion resistance of the alloy.