Characterization of Nonmetallic Inclusions in Low‐Alloyed Steels Using Pulse Distribution Analysis Optical Emission Spectroscopy and Offline Investigation Methods

Du, Hongying; Yang, A. C.; Karasev, Andrey; Jönsson, Pär G.

doi:10.1002/srin.202100223

Cited by 4 publications

References 15 publications

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Thermodynamic Constraints and Prospects for Intensified Steel Deoxidation

Holappa,

Nurmi

2024

steel research int.

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The thermodynamic constraints of steel deoxidation are discussed based on calculated [%Me]–[%O] diagrams for different deoxidizing elements in pure Fe and five examples of steel grades, highlighting the influence of alloying on the equilibria. The role of deoxidation product oxides is considered with special emphasis on the activity of SiO2 and the possibility of utilizing slags with a very low aSiO2 to amplify the deoxidizing power of silicon. This effect was verified for SiCr spring steel and 18Cr8Ni stainless steel. The results indicate a strong reduction in equilibrium oxygen content. Different means for industrial implementation of this principle are discussed. The conventional steel/slag equilibration via gas stirring is tested in practice. As potentially more efficient methods, slag powder injection (argon, lance) and cored wire injection combined with argon bubbling are studied. In such treatments, specific tailored slag additives can be used for divergent steel grades to optimize steel cleanliness and inclusion engineering.

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Thermodynamic Constraints and Prospects for Intensified Steel Deoxidation

Holappa,

Nurmi

2024

steel research int.

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Online Supervisory System for In-Process Optimization of Calcium Additions by Continuously Monitoring the State of Non-metallic Inclusions Inside Low-Alloyed Liquid Steels

Kuthe,

Rössler,

Karasev

et al. 2024

Metall Mater Trans B

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A decision support system was developed using supervised machine learning (ML) approach for optimization of calcium (Ca) additions by continuously monitoring the physical state of non-metallic inclusions (NMIs) inside low-alloyed liquid steels. In this work, two instances were considered to design the base algorithm for the proposed supervisory system: (1) Clogging of submerged entry nozzle (SEN) during continuous casting of steels due to accumulation of solid oxide non-metallic inclusions (NMIs) and (2) Ca treatment during secondary steelmaking for modification of oxide NMIs from solid to liquid state to avoid SEN clogging. At first, experimental investigations were carried out on liquid steel samples from three low-alloyed Ca-treated steel grades from the same steel family to evaluate the characteristics of solid oxide NMIs that cause SEN clogging. In the next step, data-driven models were developed using an in-house ML algorithm trained primarily with process data for calculating the value of the newly proposed dummy parameter ‘Clog.’ These models, after testing, were architected to develop a supervisory system based on experimental investigations and data-driven models. The objective of this proposed supervisory system was to predict the optimum quantity of Ca needed for successful modification of NMIs from solid to liquid state to avoid SEN clogging based on the forecasted ‘Clog’ value. Finally, industrial data from ~ 3000 heats were tested to verify the results obtained from the developed supervisory system. The results confirmed that this novel supervisory system could predict the optimum class of Ca for all studied steel grades with 95 to 98 pct accuracy. The integration of this online supervisory system in steel production is expected to minimize operators’ corrective actions in achieving realistic control of Ca additions.

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Practical Implications of Using an Online Data-Driven Optimizer for Calcium-Treated Steels

Kuthe,

Rössler,

Glaser

2024

Metall Mater Trans B

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Calcium (Ca) additions during secondary steelmaking are a well-adopted practice to transform solid oxide non-metallic inclusions (NMIs) into globular-shaped liquid oxides. The claimed hypothesis that liquid NMIs reduce SEN clogging has been proven in the past by researchers. However, the exact quantity of Ca needed to transform the physical state of NMIs during steelmaking remains uncertain. Operators in the steel plant use a consistent quantity of Ca additions for specific steel grades, but this approach does not account for the varying physical states and evolving dynamics of NMIs characteristics in each ‘heat’. To overcome this, a study was conducted to explore the impact of varying Ca additions on the transformation and behavior of NMIs in low-alloyed Ca-treated steel grades. The aim was to establish a more reliable and responsive approach to Ca treatment, potentially leading to more effective control in preventing submerged entry nozzle (SEN) clogging. The proposed methodology involved online monitoring of NMIs state coupled with controlled variations in Ca addition, deviating from fixed quantity, to observe its effects on NMIs state transformations. Through careful analysis of collected data and the implementation of a data-driven optimizer, this study reports the practical implications of using optimal amounts of Ca during secondary steelmaking. The resulting change due to dynamic calcium silicide (CaSi)-cored wire additions and their impact on SEN clogging were evaluated. The findings reveal the significant role of optimal CaSi wire additions, leading to improved steel castability and a notable 30 pct reduction in SEN clogging tendencies. The results obtained after the implementation of the data-driven optimizer ‘ClogCalc’ have significant implications for steel manufacturers, offering new insights into enhancing Ca treatment efficiency.

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Characterization of Nonmetallic Inclusions in Low‐Alloyed Steels Using Pulse Distribution Analysis Optical Emission Spectroscopy and Offline Investigation Methods

Cited by 4 publications

References 15 publications

Thermodynamic Constraints and Prospects for Intensified Steel Deoxidation

Thermodynamic Constraints and Prospects for Intensified Steel Deoxidation

Online Supervisory System for In-Process Optimization of Calcium Additions by Continuously Monitoring the State of Non-metallic Inclusions Inside Low-Alloyed Liquid Steels

Practical Implications of Using an Online Data-Driven Optimizer for Calcium-Treated Steels

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