Local Corrosion Behaviors in the Coarse-Grained Heat-Affected Zone in a Newly Developed Zr-Ti-Al-RE Deoxidized High-Strength Low-Alloy Steel

Authors：Yin, Chao-Chao; Cheng, Lin; Wang, Zhi-Hui; Zhao, Tian-Liang; Cheng, Shi; Hu, Shu-E; Liu, Zi-Cheng; Luo, Deng; Xiao, Da-Heng; Jin, Xing; Liu, Han-Kun; Wu, Kai-Ming^*

Source：Materials, 2023, 16(2): 876.

DOI：10.3390/ma16020876

• inclusion
• pitting corrosion
• HSLA steel
• CGHAZ
• first-principles
• rare earth elements

Oxide metallurgy technology can improve the microstructure of a coarse-grained heat-affected zone (CGHAZ) but introduces extra inclusions. Local corrosion behavior of the CGHAZ of a Zr-Ti-Al-RE deoxidized steel was investigated in this work using theoretical calculations and experimental verification. The modified inclusions have a (Zr-Mg-Al-Ca-RE)O-x core claded by a CaS and TiN shell. CaS dissolves first, followed by the oxide core, leaving TiN parts. This confirms that the addition of rare earth can reduce lattice distortion and prevent a galvanic couple between the inclusions and the matrix, while the chemical dissolution of CaS causes localized acidification, resulting in the pitting corrosion initiation.