Influence of cerium on impact toughness, tensile properties and inclusion of industrial Al-killed steel Q355B
Xiaofeng Zhang, Jianguo Zhi, Xiwen Song, Wangcai Diao, Bin Lü, Shengli An
Abstract
Impact toughness, tensile properties, grains, and inclusions of industrial Al-killed steel Q355B were investigated by adding cerium (Ce) from 0, 0.0028%–0.0048%. The results revealed that: (1) With the increase of Ce additions, the size of inclusions decreased and the oxide inclusions significantly decreased while oxide-sulfide inclusions significantly increased; (2) Inclusions of sample without Ce were Al2O3 and Mn(Ca)S, inclusions of sample with adding 0.0028% Ce were CeAlO3, Mn(Ca)S, and Ce2O2S, and inclusions of sample with adding 0.0048% Ce were CeAlO3, Ce2S3, Ce2O2S, and Mn(Ca)S; (3) Grains of sample with Ce were refined. Microstructure with 0.0028% Ce addition displayed a more uniform ferrite and microstructure with 0.0048% Ce addition exhibited a more uniform pearlite, which was due to Ce2O2S as effective nucleating agent for α-Fe and MnS as effective nucleating agent for γ-Fe; (4) Impact toughness and yield strength of sample with 0.0028% Ce addition was highest in the three samples, because of the microstructure of refining and uniform ferrite grains and small Ce-based inclusions.