In the world of steel production, the devil is often in the details—or more precisely, in the carbon. A recent study published in *Teshugang* (which translates to *Iron and Steel* in English) has shed new light on how the continuous casting process influences carbon segregation in steel billets, a critical factor that can make or break the quality of the final product. The research, led by Ren Hongwa, offers a roadmap for optimizing the process to enhance the performance and longevity of steel products, particularly in the energy sector.
Carbon segregation, the uneven distribution of carbon within steel, is a persistent challenge that can lead to defects such as banded structures and heat treatment issues. These defects not only compromise the mechanical properties of the steel but also reduce its service life, a significant concern for industries that rely on high-performance materials. “This defect persists throughout the entire process from hot rolling to product service, severely deteriorating material processability,” Ren Hongwa explains. “It induces banded structures and heat treatment defects, and significantly reduces the mechanical properties and service life of the final product.”
The study systematically investigated the carbon macrosegregation behavior of low-carbon, medium-carbon, and high-carbon alloy steels under various continuous casting process parameters, including superheat, casting speed, and mold electromagnetic stirring (M-EMS). The findings are nothing short of transformative for the industry. For instance, the research defines optimized process windows for typical steel grades. For low-carbon steel 20CrMo, a superheat of 20°C–25°C, a casting speed of ≤1.60 m/min, and an M-EMS current of 195A–205A are recommended. Similarly, tailored recommendations are provided for medium-carbon and high-carbon steels.
One of the most compelling aspects of the study is its quantification of the influence of key continuous casting parameters on carbon macrosegregation. The research reveals that as the carbon content of the steel grade increases, the proportion of negative segregation from the strand center to the 1/2 radius region decreases. Additionally, the inner arc/outer arc negative segregation ratio also diminishes. “Within a specific magnetic field intensity range, enhancing M-EMS effectively reduces the fluctuation range of the carbon segregation index,” Ren Hongwa notes. This finding underscores the importance of electromagnetic stirring in achieving uniform carbon distribution.
The study also highlights the critical role of superheat and casting speed. It was found that a tundish superheat within the range of 20°C–30°C yields the optimal carbon segregation index, while increasing the casting speed leads to a significant rise in the carbon segregation index of the strand. These insights provide a direct basis for effectively controlling carbon macrosegregation in industrial production by optimizing parameters such as superheat, electromagnetic stirring intensity, and casting speed.
The implications of this research are far-reaching, particularly for the energy sector, where high-performance steel is crucial for applications ranging from power generation to renewable energy infrastructure. By optimizing the continuous casting process, manufacturers can produce steel with superior mechanical properties and extended service life, ultimately enhancing the reliability and efficiency of energy systems.
Ren Hongwa’s work not only advances our understanding of carbon segregation but also paves the way for targeted process optimization based on the steel grade’s carbon content. As the industry continues to evolve, this research will undoubtedly shape future developments, ensuring that the steel we rely on is of the highest quality and performance.