Morphology and growth of alumina inclusions in Fe–Al alloys at low oxygen partial pressure

Ende, M A; Guo, Muxing; Zinngrebe, Enno; Dekkers, Rob; Proost, Joris; Blanpain, Bart; Wollants, Patrick

doi:10.1179/174328109x401550

Cited by 29 publications

(20 citation statements)

References 15 publications

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“…[1][2][3][4][5][6][7] Zhang et al 1) studied the size distribution of Al 2 O 3 inclusions after deoxidization of steel according to the static model by considering the theories of nucleation, growth by diffusion and the various mechanisms of collision. Kwon 4) modified it into dynamic model in consideration of inclusion removal, time and space dependence of temperature and fluid patterns in ladle by a Computational Fluid Dynamics (CFD) model.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Non-Metallic Inclusions in Ultra Low Carbon Steel after Aluminum Deoxidization

et al. 2014

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A new technique based on the PDF (Population Density Function) was suggested to investigate the behavior of non-metallic inclusions after deoxidization. In comparison with the traditional analysis using the size histogram of inclusions, the application of PDF can make it possible to attain more useful information to understand the evolution of inclusions such as the period of formation and mechanism for growth. In this study, the PDF of alumina inclusions was investigated for the ultra low carbon grade steel of 20 ppm C. The lollypop samples were taken at three stages after deoxidization using aluminum; at the end of RH degassing process, at tundish during casting operations, and in cast slabs after solidification. For all the samples except for the contaminated ones, the PDF shows a fractal distribution. The exponent in fractal distribution was -3.54 near the end of RH process at 7-13 minutes after deoxidization, which is similar with the previously reported value. In contrast, the exponent was changed to -2.76 in tundish and -2.38 in cast slab, respectively. Different expressions of the fractal distribution can be attributed to the changes in fluid condition of molten steel. The application of PDF also provides the quantitative evaluation for abnormal reoxidization of molten steel. The deviation of PDF from the reference distribution is in accordance with other evidences of reoxidization of molten steel such as the increase of nitrogen pick-up and the decrease of soluble aluminum.

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Section: Introductionmentioning

confidence: 99%

Evolution of Non-Metallic Inclusions in Ultra Low Carbon Steel after Aluminum Deoxidization

et al. 2014

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“…The stereologically corrected PDFs were calculated for all inclusion populations using this method and plotted against the equivalent inclusion diameter, a standard plotting procedure on which phenomenologically and genetically distinct distribution functions can most easily be discriminated. A detailed discussion of the PDF representation and the procedure to calculate PDF plots are given in previous studies 13,14) as well as the paper by Van Ende et al 6) …”

Section: Inclusion Population Density Function (Pdf)mentioning

confidence: 99%

“…5) can be fitted well as lognormal size distributions: 13,14) . It has to be noted that nearly all the apparent lognormal curves given in Fig.…”

Section: Existence Of Liquid Ti-al-o Oxide Inclusionsmentioning

confidence: 99%

Inclusion Population Evolution in Ti-alloyed Al-killed Steel during Secondary Steelmaking Process

et al. 2012

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This paper presents a new approach towards the evolution of non-metallic inclusion (NMI) populations in Ti-alloyed Al-killed steels, based on an extensive inclusion analysis campaign at Tata Steel Europe, IJmuiden Works. Automated SEM techniques were used to characterize the inclusion populations in 120 steel samples taken from nine heats out of two casting series of this steel grade. As NMI in Ti-alloyed Alkilled steels are overwhelmingly dominated by chemically simple Al2O3, most of the process relevant information lies in the analysis of particle size distribution during the secondary steelmaking process. The population density function (PDF) concept was applied, for the first time, to the characterization of inclusion size distributions sampled from secondary steelmaking practice. Two size distribution forms predominate in the entire dataset: i) Lognormal size distributions associated with active nucleation and growth of alumina (deoxidation and reoxidation), indicating net transfer of matter between NMI and solutes in liquid steel and ii) Power-law size distributions, associated with an inclusion population in chemical equilibrium with the melt and subject to collision/breakup processes controlling the distributions. Based on inclusion PDF observations, it is found that the size distribution of alumina inclusions suspended in steel melt, after equilibration and effective float out of large inclusions, tends to approach a Reference Distribution of powerlaw type function (f(r) = a ⋅ r -3.5 ) that appears to be a fundamental feature of the alumina-steel system. This Reference Distribution can guide efforts to improve and engineer inclusion populations for a better controlled steel product.KEY WORDS: non-metallic inclusion; inclusion population density function; inclusion size distribution; secondary steelmaking.

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“…Definitions of the fractal and lognormal distributions and their properties can be found elsewhere. 27,28) …”

Section: Statistical Distributions To Represent Inclusionmentioning

confidence: 99%

Evolution of Non-Metallic Inclusions in Secondary Steelmaking: Learning from Inclusion Size Distributions

et al. 2013

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Non-metallic inclusions have always been the active subject of steelmaking research to improve the steel cleanliness and to develop the so-called oxide metallurgy technology. Inclusions in molten steel form and grow by the sequence of nucleation, chemical and physical growth and removal. Thus, the size distribution of inclusions evolves continuously with time in molten steel, and significant changes in the steel conditions are reflected in the inclusion size distribution as well as in the inclusion chemistry. This study aims to provide a new approach to interpret the inclusion size distributions. The concept of the Population Density Function (PDF) is introduced to objectively represent a given inclusion size distribution. Several possible applications of PDF analysis are presented to demonstrate the advantages of the utilization of the PDF for understanding the inclusion formation mechanism during the steelmaking process. Several ambitious ideas to utilize the PDF for inclusion size control are also presented.

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Morphology and growth of alumina inclusions in Fe–Al alloys at low oxygen partial pressure

Cited by 29 publications

References 15 publications

Evolution of Non-Metallic Inclusions in Ultra Low Carbon Steel after Aluminum Deoxidization

Evolution of Non-Metallic Inclusions in Ultra Low Carbon Steel after Aluminum Deoxidization

Inclusion Population Evolution in Ti-alloyed Al-killed Steel during Secondary Steelmaking Process

Evolution of Non-Metallic Inclusions in Secondary Steelmaking: Learning from Inclusion Size Distributions

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