Yong-kun Yang, Jia-yu Zhu, Wei-an Wang, Yang Wang, Jian-li Wang, Guan-jie Wang, Xiao-ming Li1
Central crack is a common quality defect in continuous casting strand, which is difficult to fully weld in the rolling and forging processes, and has become a key technical problem that restricts the stable production of high-end alloy rod/forging/pipe. In recent years, the central crack control has been one of the main focuses in high quality steel research. In order to fully understand the central crack, the research status of central crack characteristics, formation mechanism, influencing factors, and control methods in the world was reviewed. The deficiencies in the research of the central crack and the key research directions in the future were pointed out, which will provide references for other scholars in this field of research. It is found that alloying elements segregation during solidification and inclusions precipitated at grain boundaries are the main reasons for the central crack formation, while the unreasonable application of production processes can also induce the initiation of central crack. The optimization of alloying element composition and production process is helpful to reduce the initiation of central cracks. In addition, the quantitative characterization mechanism based on steel grades, temperature, stress, and other factors induced central crack should be established in the further study, forming a systematic quantitative determination criterion and control strategy for coupling the composition, process and thermal/ mechanical characteristic.
