Effect of Molten Steel Composition on Inclusion Modification by Calcium Treatment in Al-Killed Tinplate Steel

Abstract

The effects of oxygen, magnesium, and sulfur content in Al-killed tinplate steel on the "liquid zone" of inclusion modification by calcium treatment were clarified through industrial experiments and thermodynamic calculation, and the characteristics of inclusions modification were studied. The results show that the inclusions in molten steel before calcium treatment are mainly Al 2 O 3 inclusions.The inclusions in molten steel are CaO•Al 2 O 3 after calcium treatment with a holding time of 10min, while the inclusions are mainly 3CaO•Al 2 O 3 with a holding time of 30min. And 12CaO•7Al 2 O 3 inclusions are observed in molten steel when T.O content increases to 40ppm after calcium treatment with a holding time of 30min. As the increase of T.O content from 10ppm to 40ppm, the difference between the upper and lower limits of the critical calcium content corresponding to the "liquid zone" increases from 5ppm to 17ppm. The increase of T.O content in molten steel will enlarge the "liquid zone" range of inclusion modification by calcium treatment, and increase the critical calcium content.With the increase of magnesium content in molten steel, the liquid phase ratio of inclusions modification by calcium treatment decreases. To obtain the liquid phase ratio of inclusions at least 50% in molten steel, not only the calcium content in steel should be strictly controlled, but also the magnesium content in steel should not be larger than 15ppm. With the increase of sulfur content in molten steel, the "liquid zone" range of inclusion modification by calcium treatment becomes narrow.

Study of Assimilation of Cored Wire into Liquid Steel Baths

“…The range of the error bars for the "experiment"-axis corresponds to the results shown in Table 3; for the "simulation"-axis, the range of the error bars corresponds to the change in thickness as the magnitudes of the contact thermal resistances are changed. Since the model matches the experimental conditions of the immersion of the cored wires, it is expected that simulations extrapolating to industrial processing conditions would allow for producing guidelines for optimization of the cored wire injection process, as a complement to established approaches that combine industrial trials with thermodynamic analyses [44][45][46][47][48][49][50][51][52][53][54][55]. lation"-axis, the range of the error bars corresponds to the change in thickness as the magnitudes of the contact thermal resistances are changed.…”

Evolution behaviour and modification mechanism of inclusions in NM500 wear-resistant steel with calcium treatment

“…Based on the published papers , the industrial experimental research results with calcium treatment from 2011 to 2021 are summarized as shown in Table 1. According to Table 1, thermodynamic calculation and SEM-EDS analysis are widely used to study the formation and modification mechanism of inclusions in different steel grades, the evolution law of compositions, sizes, numbers and morphology characteristics of the different inclusions after calcium treatment in different steel grades [1][2][3]6,8,10,[12][13][14][21][22][23][24][25][26], and the optimization and improvement of calcium treatment process [4,5,9,20,29], as well as the mechanism reducing nozzle nodulation and the degree of tundish stopper erosion with calcium treatment [27,28]. The modification and local concentration of inclusions, rate-controlling step of inclusion modification and change of inclusion compositions with different reaction times in calcium treatment steel can be studied in combination with numerical simulation and kinetic models [7,11,[15][16][17][18][19].…”