Oxide Scales on Commercial Hot Rolled 1.5%Si Non-oriented Electrical Steel and the Pickling Behaviors

• Published in: Metallography, microstructure, and analysis microstructure, and analysis, 2022-04, Vol.11 (2), p.183-190
• Main Authors: Li, Hui, Wu, Shengjie, Lu, Jiadong, Yue, Chongxiang
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Composition; Descaling; Electrical steels; Hot rolling; Iron oxides; Materials Science; Metal strips; Metallic Materials; Microcracks; Nanotechnology; Peer Reviewed; Pickling; Scale (corrosion); Strip steel; Structural Materials; Surfaces and Interfaces; Tensile tests; Thickness; Thin Films
• ISSN: 2192-9262; 2192-9270
• DOI: 10.1007/s13632-022-00830-5

The surface of commercial hot rolled 1.5%Si non-oriented electrical steel before and after pickling generally exhibit color deviation in width, indicating different structure composition and pickling behavior of scales from the strip edge to center. The present study investigates the oxide scale structures at different parts of the strip by means of x-ray diffraction and scanning electron microscope, and their mechanical descaling properties are evaluated by tensile test. The results show that oxide scales at the strip edge and center are different in thickness and structure composition because of the difference in temperature and oxygen supply in width direction of the hot rolled coils. Oxide scales at the edge are thinner and comprise Fe 2 O 3 and Fe 3 O 4 , while scales at the center are thicker, and mainly consist of Fe 3 O 4 and FeO, meanwhile, it has thicker Si-rich layer in the substrate-scale interface which can impede the acid pickling process, resulting in dark appearance on the pickled steel strips. Besides, the high content of FeO at the strip center can absorb some stress and disfavors the generation of microcracks in the mechanical descaling test, which may further increase the difficulty of acid pickling.