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Assessment of Nonhomogeneous Structures in Steel Contents in Terms of Fatigue Resistance Using Analytical Hierarchy Process

Al-Maliki Ali, AL-Bedhany Jasim H., Mankhi Tahseen Ali, Legutko Stanislaw

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no 1

334--348

EN

Fatigue resistance of steel containing non-metallic inclusions (NMIs) varies widely, depending on many criteria; therefore, finding the most compromised types of NMIs is a sober objective that may significantly reduce severe damage and premature failure in many applications, such as bearings, gears, transmission shafts, etc. The Multiple Criteria Decision-Making (MCDM) methodologies have been used in this study to assess the more effective NMI types using the Analytical Hierarchy Process (AHP) by Expert Choice (EC) software. The five most common types of non-metallic inclusions selected are oxides, sulfides, carbides, silicates, and nitrides, based on different criteria: size, shape, distribution, mechanical properties, and quantity. The results showed that the oxide NMIs are the optimum type relative to the other four options regarding the fatigue resistance of about 35%, probably due to their spherical shape and small size. The most dominant criterion is mechanical properties, which have an effective percentage of 34.6% among the other criteria. It means that the reduction of other types rather than oxide NMIs probably enhances the fatigue resistance of the steel.

2

Review of Titanium Related Inclusions in Casting of Steel

Sheikh Ali R.

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 2

127--136

EN

The general area of understanding is inclusions in steel both metallic and nonmetallic in nature. This work has also used the concepts of inclusions in steel in general other than Ti however mainly the research works done on precipitation, solute segregation, grain developments and equilibrium aspects of important inclusions like Ti in steel have been probed. Interaction of inclusions with slag oxides has also been incorporated. Interdependence of elements common in-between many inclusions has been marked. TiN, TixOy and MnS inclusions have been very outstanding in the confines of present research. Ratios and effective concentration have been highlighted in certain cases around the topic. Type of steels, compositions of the constituent elements and temperature correlation has been spotted in certain environments. A suggestive relation with the steel properties has also been inferred. Hardness, corrosion behaviour and strength stand out to be the parameters of vital importance when considering Ti inclusions in the form of either TiN or TixOy. Certain inclusions like MnS seem to nucleate on TiN inclusions and there is a correlation evident certainly in case of complex alloys.

3

Efficiency of Aluminum Oxide Inclusions Removal from Liquid Steel as a Result of Collisions and Agglomeration on Ceramic Filters

Kalisz D., Kuglin K.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 2

43--48

EN

Filtration is one of the most efficient methods of removing Al2O3 inclusions from liquid steel. The efficiency of this process depends on the physicochemical parameters of liquid metal, inclusion and properties of the applied filters. The particles attracted during filtration undergo agglomeration, collisions and chemical reactions on the filter surface, with the emphasis on the mechanism of particle collisions and the role of material from which the filter was made. The aluminum oxide inclusions collide with the filter surface and as the growing process continues, the particles also collide with the previously adsorbed inclusions. At the interface of particle and filter the mixing of the metal bath is most intense, being a result of a sudden change of flow direction and breaking up the stream of liquid metal which is in a direct contact with material. The efficiency of filtration is defined not only by the behavior of individual particles but of all population. The simulations revealed that only a small fraction of these particles adheres directly to the filter material; most of them stick to the former ones. Attention should be also paid to the fact that some of the inclusions which contacted the filter walls do not form a permanent connection and are then entrained by metal. Authors solved the problem of agglomeration and collisions of Al2O3 inclusions with the ceramic surface of the filter with the PSG method, mainly used for the analysis of agglomeration of inclusions during steel refining in the ladle.

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Study of Nonmetallic Inclusions in Aluminum–Silicon Alloys

Galek Tomasz, Łączek Andrzej, Łysiak Karol

Advances in Manufacturing Science and Technology

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2020

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Vol. 44, nr 1

28-31

EN

In this article, a study of nonmetallic inclusions introduced during the casting process of the aluminum–silicon alloy is presented. The samples were investigated using a scanning electron microscope to find the chemical composition and X-ray tomography to check the volumetric content of the non-metallic inclusions. The samples were made from AlSi7Mg alloy, used for car wheels, with 7% weight content of Si, 89% of Al, and 0.3% of Mg. The main goal of our investigations was to find out the chemical composition of the impurities and to identify the stage of the casting process at which the impurities are introduced.

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Nonmetallic Inclusions in a New Alloy for Single-Crystal Permanent Magnets

Belyaev I. V., Bazhenov V. E., Kireev A. V., Moiseev A. V.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 2

11--14

EN

The morphology, chemical composition and formation mechanism of non-metallic inclusions in magnetic alloy of Fe-Co-Ni-Cu-Al-Ti-Hf system were investigated. These alloys are used in manufacturing single-crystal permanent magnets. Modern methods for the identification of non-metallic inclusions, as well as computer simulation of the processes of their formation by Thermo Calc software were used in the work. It was found that studied alloy contains (Ti, Hf)S titanium and hafnium sulfides, (Ti, Hf)2SC titanium and hafnium carbosulfides, Ti2O2S titanium oxisulfide, HfO2 hafnium oxide, and Al2O3 aluminum oxide. No titanium and hafnium nitrides were found in the alloy. The bulk of nonmetallic inclusions are (Ti, Hf)2SC carbosulfides and (Ti, Hf)S sulfides. All carbides and many oxides are within carbosulfides and sulfides. When the sulfur content in the alloy is no more than 0.2%, and carbon content does not exceed 0.03%, carbosulfides are formed in the solidification range of the alloy and has an faceted compact form. If the sulfur content in the alloy becomes more than 0.2% and carbon content more than 0.03%, the carbosulfide formation begins before the alloy solidification or at the beginning stages of solidification. In this case, carbosulfides are dendritic and coarse. Such carbosulfides actively float in the solidified melt and often come to the surface of the castings. In this case, specific surface defects are formed in single-crystal magnets, which are called sulfide stains. All titanium and hafnium sulfides are formed at the lower part of solidification range and have elongated shape.