Offset Effect of Chromium on the Adverse Impact of Manganese in a Low-C Medium-Mn Steel with Reversed Austenite in the Neutral Salt Spray Condition

This work used the neutral salt spray test to investigate the effects of microstructure and alloy elements on the corrosion process of medium manganese steel by analyzing the microstructure, corrosion rates, morphology, and corrosion phase of the surface, and cross-section products, as well as the elemental distribution and valence state of the rust films. The results show that the microstructure of the tested steel consists of martensite and reversed transformation austenite; the corrosion behavior of the designed steel is affected by the microstructure and alloy elements. Mn-rich compounds play a negative role during the corrosion process; with increasing corrosion time and in the presence of anti-corrosion elements, Cr may form a barrier to repel the cation permeability produced by Mn-rich compounds to stabilize the corrosion rate. In addition, the reversed transformation austenite plays a positive role in regulating the corrosion process.