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<p>During continuous casting of steel, mold-level fluctuation is inherent, yet abnormal mold-level fluctuation (AMLF) severely influences slab surface quality. Although bulging, submerged entry nozzle (SEN) clogging, casting speed variations, and stopper-rod position are known to influence the fluctuations, there is a lack of quantitative studies on mold flux behavior. This study investigated the effects of high-basicity (pct CaO/pct SiO<sub>2</sub>, <i>R</i> = 1.42) and low-basicity (<i>R</i> = 1.08) mold fluxes on the AMLF for high-nitrogen stainless steel casting. Mold-level fluctuation data were analyzed by Fast Fourier Transform (FFT), the heat control abilities of the mold fluxes were monitored in real time, and their crystallization behaviors were observed using Double Hot Thermocouple Technique (DHTT) at a temperature gradient (700 °C to 1400&#xa0;°C). The results showed that the high-basicity flux induces the AMLF with amplitudes up to ±&#xa0;4&#xa0;mm, whereas the low-basicity flux maintains a stable level. FFT analysis identified a dominant mold-level fluctuation frequency of 0.185 Hz, which matched the frequency of bulging at the first row of support rolls (0.190 Hz) and transverse depression (0.193 Hz). Compared with low-basicity mold flux, high-basicity mold flux formed a thicker slag film with stronger crystallization ability and reduced the 200 kW/m<sup>2</sup> heat flux, promoting the thinner solidified shell at mold exit. Then, bulging was formed at first row of support rolls, propagating AMLF and ultimately generating periodic transverse depressions. Combining FFT analysis of mold-level fluctuations with DHTT detection of slag film thermal control ability can quantify the effects of mold flux. This method not only guides mold flux optimization but also enhances slab quality and process stability.</p>

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Effects of Mold Flux on Abnormal Mold-Level Fluctuation During Slab Continuous Casting

  • 期刊论文

  • 发表日期：

    2025年12月17日

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  • Qiuping Li,
  • Qingmao Kong,
  • Guanghua Wen,
  • Ping Tang,
  • Zibing Hou

摘要

During continuous casting of steel, mold-level fluctuation is inherent, yet abnormal mold-level fluctuation (AMLF) severely influences slab surface quality. Although bulging, submerged entry nozzle (SEN) clogging, casting speed variations, and stopper-rod position are known to influence the fluctuations, there is a lack of quantitative studies on mold flux behavior. This study investigated the effects of high-basicity (pct CaO/pct SiO2, R = 1.42) and low-basicity (R = 1.08) mold fluxes on the AMLF for high-nitrogen stainless steel casting. Mold-level fluctuation data were analyzed by Fast Fourier Transform (FFT), the heat control abilities of the mold fluxes were monitored in real time, and their crystallization behaviors were observed using Double Hot Thermocouple Technique (DHTT) at a temperature gradient (700 °C to 1400 °C). The results showed that the high-basicity flux induces the AMLF with amplitudes up to ± 4 mm, whereas the low-basicity flux maintains a stable level. FFT analysis identified a dominant mold-level fluctuation frequency of 0.185 Hz, which matched the frequency of bulging at the first row of support rolls (0.190 Hz) and transverse depression (0.193 Hz). Compared with low-basicity mold flux, high-basicity mold flux formed a thicker slag film with stronger crystallization ability and reduced the 200 kW/m2 heat flux, promoting the thinner solidified shell at mold exit. Then, bulging was formed at first row of support rolls, propagating AMLF and ultimately generating periodic transverse depressions. Combining FFT analysis of mold-level fluctuations with DHTT detection of slag film thermal control ability can quantify the effects of mold flux. This method not only guides mold flux optimization but also enhances slab quality and process stability.