Influence of Cr and Ni elements on the electrochemical and early corrosion behavior of FeMnAlC low-density steel

Abstract

FeMnAlC low-density steel (LDS) is considered to be a promising material due to its good mechanical properties and light weight, its corrosion resistance, however, needs to be improved. In this paper, the effect of Cr and Ni on the electrochemical and early corrosion behavior of a Fe–25Mn–10Al–1.5C LDS in a 3.5% NaCl solution was studied through microstructure characterization, electrochemical tests and immersion tests. The results showed that Cr and Ni alloying reduced the austenite grain size and promoted the formation of the B2 phase. Adding 2% Cr or Ni to the Fe–25Mn–10Al–1.5C LDS clearly inhibited the electrochemical activity and initial micro galvanic effect between the second phases and the austenite. Moreover, the properties of the corrosion product film were optimized, and the local corrosion process beneath the product film was mitigated. Compared with 2% Cr addition, 2% Ni addition improved the corrosion resistance of the FeMnAlC LDS better from the aspects of electrochemistry, corrosion product film and corrosion mode.

Keywords

• Low-density steel
• Cr/Ni alloying
• Corrosion resistance
• Electrochemistry
• Localized corrosion
• Corrosion product film