Anomaly Detection in Asset Degradation Process Using Variational Autoencoder and Explanations

Development of predictive maintenance (PdM) solutions is one of the key aspects of Industry 4.0. In recent years, more attention has been paid to data-driven techniques, which use machine learning to monitor the health of an industrial asset. The major issue in the implementation of PdM models is a lack of good quality labelled data. In the paper we present how unsupervised learning using a variational autoencoder may be used to monitor the wear of rolls in a hot strip mill, a part of a steel-making site. As an additional benchmark we use a simulated turbofan engine data set provided by NASA. We also use explainability methods in order to understand the model’s predictions. The results show that the variational autoencoder slightly outperforms the base autoencoder architecture in anomaly detection tasks. However, its performance on the real use-case does not make it a production-ready solution for industry and should be a matter of further research. Furthermore, the information obtained from the explainability model can increase the reliability of the proposed artificial intelligence-based solution.

Modern view on steel desulfurization

Modern technological schemes of steel production do not allow to achieve low (< 0.01 % S) and ultra-low (<0.005 % S) sulfur content on the production of in the metal directly. That is why out-of-furnace steel treatment is often used to remove sulfur. Desulfurization process of steel depends on the chemical composition of the slag, the time of its formation in the ladle, metal oxidation, conditions of mixing of steel in a ladle, additional technological operations and ladle metal processing. Methods are widely used for desulfurization of steel treatment of steel with solid slag-forming mixtures, synthetic slag, lime-aluminous slag, silico-calcium and other powdered materials. Modern approaches to the process of steel desulfurization in conditions steel production are analyzed in the Study. In particular, the Ukrainian (on the example of PJSC ‘Azovstal Iron & Steel Works’ and PJSC ‘Dneprovsky Integrated Iron & Steel Works named after Dzershinsky’) and foreign (on the example of PJSC ‘Severstal’ and PJSC ‘Magnitogorsk Iron & Steel Works’) experience of desulfurization under oxygen converter production. The use of technological complexes ‘Installation of pig iron desulfurization steel making unit’ and ‘Cast iron desulfurization installation steel making unit is ‘oven-bucket’ installation’ provides a deeper desulfurization of steel, the possibility of optimizing the cost of steel production, expands range of scarce products and eliminates a number of restrictive conditions that complicate current production. The analysis of steel C80D desulfurization process is given in the conditions of JSC ‘Moldova Steel Works’, in which partial sulfur removal occurs in an arc steel making furnace, and the ultra-low content is achieved by creating a highly basic refining slag in the process out-of-furnace processing of steel. The study of the kinetics of the desulfurization process of 20GL steel in the conditions of JSC ‘Tashkent Mechanical Plant’ with the use of solid slag-forming mixtures and modification of steel with rare-earth metals is analyzed. The issue of desulfurization of electric steel in the conditions of OJSC ‘Byelorussian Steel Works’ with injection of powdered materials through the installation ‘Velko’ during out-of-furnace processing of steel is considered. Keywords: steel desulfurization, desulfurizer reagent, degree of desulfurization, cast iron desulfurization installation, out-of-furnace processing of steel, ‘‘oven-bucket’’ installation.

Monitoring the oxygen removal process at the final stage of melting steel

This article deals with removing oxygen at the final stage of steel smelting in arc steel-making furnaces. It is shown that the remaining oxygen during crystallization forms floccules and significantly reduces the quality of the finished metal. During the subsequent metal processing by pressure on these floccules, the metal is torn apart and makes it impossible to obtain a steel sheet. Deoxidation is performed with expensive ferroalloys, and their consumption must be minimized. To achieve economic efficiency, it has been proposed to use recycled aluminum slag as a relatively inexpensive local deoxidizer. To optimize the deoxidizer consumption, a rapid analysis method was developed using the electromotive force (EMF) determination to determine the oxygen activity in liquid steel. As a result of the study, the composition, structure, and technological parameters of deoxidized steel were determined. The use of this technology in production will make it possible to obtain high-quality steel and improve environmental protection through secondary aluminum waste.

Evaluation of Antioxidant and Anticorrosive Activities of Ceriops tagal Plant Extract

Mangroves are plants known for their various medicinal and economical values, and therefore are widely investigated for their phytochemical, antioxidant, antidiarrheal, and antimicrobial activities. In the present study, we analyze the antioxidant and anticorrosive properties of Ceriops tagal (C. tagal), a tropical and subtropical mangrove plant of the Rhizophoraceae family. The total phenolic content (TPC) and total flavonoid content (TFC) were found to be 101.52 and 35.71 mg/g, respectively. The extract (100 µg/mL) exhibited 83.88, 85, and 87% antioxidant property against 1,1-diphenyl-2-picrylhydrazyl (DPPH), nitric oxide, and hydrogen peroxide free radicals. In addition, 600 ppm of C. tagal extract showed 95% corrosion inhibition against 1 M HCl attack on mild steel at 303 ± 1 K, which declined over other concentrations and temperatures, where AAS produced 82% inhibition at 600 ppm. UV-visible spectroscopy analysis revealed the formation of an inhibitor metal complex. The elemental analysis provided the presence of 84.21, 9.01, and 6.37% of Fe, O, and C, respectively, in inhibited mild steel, whereas the same were 71.54, 22.1, and 4.34%, respectively, in uninhibited specimen, stressing the presence of protective film on the metal surface. Scanning electron microscopy (SEM) also showed some noteworthy changes in both uninhibited and inhibited mild steel, making C. tagal plant a better alternative than any other synthetic inhibitors. Further, the atomic force microscopy (AFM) surface topography analysis showed that 600 ppm of C. tagal extract significantly diminished corrosion on the surface of mild steel.

Prospects for using boron in metallurgy. Report 2

The second part of the article presents perspective directions of using boron and its compounds in the preparation processes, metallurgical processing of ore materials and steel smelting in order to improve the quality of the final product. An efficient technology of silicothermal production of ferrosilicoboron containing 0.6 – 2.0 % B and 60 – 80 % Si has been developed. The advantage of this scheme is the possibility of obtaining a boron-containing alloy during ferrosilicon smelting. It has been experimentally shown that ferrosilicoboron has higher performance characteristics than ferroboron both in production and when used for steel processing. The results of industrial tests of the technology for microalloying pipe grades of steel with a new ferroalloy with boron confirmed a high degree of boron assimilation – up to 96 %. The possibility of widespread use of boron for steel microalloying is due to its cheapness, availability and environmental friendliness. According to the calculations, boron from complex ferrosilicoboron is the cheapest trace element used to increase the strength characteristics of steel. Additives of B2O3 can be successfully used to form high-magnesium liquid steel-making slags. It is shown that 0.37 – 0.55 % В2О3 effectively stabilizes the highly basic slags of the steel and ferroalloy industries. This operation allows obtaining a marketable lump material. The above review, results of the laboratory and industrial studies have shown the effectiveness of boron usage at different stages of metallurgical production. An increase in technical and economic indicators of production and quality of steel and ferroalloys, and effective disposal of waste slags is shown. The technical solutions advanced and tested at metallurgical enterprises do not require capital expenditures. They are implemented by adding microdosing of boron and its compounds to metallurgical production facilities.