Effect of inclusions modified by rare earth elements (Ce, La) on localized marine corrosion in Q460NH weathering steel

• Published in: Corrosion science Vol. 129; pp. 82 - 90
• Main Authors: Liu, Chao, Revilla, Reynier I., Liu, Zhiyong, Zhang, Dawei, Li, Xiaogang, Terryn, Herman
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01.12.2017; Elsevier BV
• Subjects: AFM; Atmospheric corrosion; Carbon steel; Corrosion effects; Corrosion resistance; Corrosion resistant steels; Electron microscopy; Emission analysis; Field emission microscopy; Immersion tests (corrosion); Inclusion; Inclusions; Marine corrosion; Marine environment; Pitting corrosion; Rare earth elements; Scanning electron microscopy; SEM; Steel; Structural steels; Studies; Trace elements; Weathering steels; AFM; Pitting corrosion; Carbon steel; SEM; Inclusion
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2017.10.001

•The initial stages of the pitting corrosion of Q460NH steel in a marine environment was studied.•Two different types of inclusions formed in the Q460NH steel after adding rare earth.•Both types of inclusions showed a lower Volta potential than the matrix.•Pitting corrosion was induced by the dissolution of inclusions rather than the matrix.•Inclusions containing (RE)AlO3 dissolved completely as a result of the acidic solution formed in the pits. In this work the initial stages of the pitting corrosion in Q460NH weathering steel in a marine environment was studied. To elucidate the effects of inclusions modified by rare earth (RE) elements on pitting corrosion, field emission-scanning electron microscopy-energy dispersive spectrometry (FE-SEM-EDS) analyses, scanning Kelvin probe force microscopy (SKPFM) tests, and a series of immersion tests were conducted. Two main types of inclusions were formed in the steel, and different pit morphologies were observed. The pitting corrosion was initiated by the dissolution of (RE)2O2S-(RE)xSy in both types of inclusions due to the lower potential of this phase compared to the matrix, which indicated that the inclusions in the Q460NH weathering steel had a lower pitting corrosion resistance than the matrix.