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Formation Mechanism for the TiN-MnS Complex Inclusions in Tire Cord Steel

Lei Jialiu, Wang Xiumin, Zhao Dongnan, Fu Yongjun

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 2

65--69

EN

High strength tire cord steel is extensively used in radial ply tyres as the framework material, but the presence of brittle single titanium inclusions or complex titanium inclusions can cause failure of the wires and jeopardize their performance in production. In order to provide a key guidance on the control of titanium inclusions, it is necessary to clarify their formation mechanism during solidification. In the present work, the thermodynamic calculations were employed for an elaboration on their formation mechanism, combined with the industrial test. The TiN-MnS complex inclusions observed by SEM-EDS shows that the internal corresponds to TiN and the external is MnS. Thermodynamic calculations based on the microsegregation model indicate that MnS forms first, which can act as a nucleation site for the co-deposit of TiN in the mushy zone. As the MnS inclusions have a better deformation than that of TiN inclusions, then the TiN inclusions are wrapped by the MnS inclusions, generating TiN-MnS complex inclusions after rolling.

2

Feasibility study on preparation of magnesium titanate in carbonthermic reduction of vanadium titanomagnetite concentrates

Chen Chao, Sun Ti-Chang, Kou Jue, Wang Xiao-Ping, Zhao Yong-Qiang

Physicochemical Problems of Mineral Processing

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2019

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Vol. 55, iss. 2

417--425

EN

Effect of temperature and Mg:Ti ratio on phase composition and microstructure of reduced pellets was investigated to verify the feasibility of preparation of magnesium titanate by adding MgO in carbonthermic reduction of the vanadium titanomagnetite concentrates (VTC). Thermodynamic analysis results showed that magnesium titanate is more easily generated than FeTi2O5 or TiO2 by the reaction of FeTiO3 and MgO under the reductive atmosphere, which was confirmed by the discovery of magnesium titanate at roast experiment. It was found that the optimum conditions for reduction of VTC pellets were temperature of 1250 ºC and Mg:Ti ratio of 2, and the main phases of reduction product were metallic Fe and magnesium titanate (Mg2TiO4). However, trace iron impurities in Mg2TiO4 particles were found by energy-dispersive spectroscopy (EDS), so further purification is required.

3

Study on the behavior of streamwise vortices formed between leading edge tubercles in a compressor cascade

Zheng Tan, Qiang Xiao-Qing, Teng Jin-Fang, Feng Jin-Zhang

Journal of Theoretical and Applied Mechanics

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2019

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Vol. 57 nr 3

617--629

EN

A study has been carried out to investigate the formation mechanism and development of streamwise vortices induced by leading edge tubercles in a high speed compressor cascade. The preliminary assessment of the cascade performance in terms of the total pressure loss coefficient shows that the loss reduction is achieved at high incidence angles. A smaller wavelength leads to higher additional losses at the design point, but gives rise to a greater loss reduction at high incidence angles. The modified cascade with a tubercle wavelength of 4% chord achieves the maximum loss reduction of 36.1% at i = 10◦ , as well as the stall angle improvement of 27.6%. The formation mechanism of streamwise vortices is elaborated on the basis of the streamwise vorticity equation, in which the streamwise turning terms may be responsible for the generation of streamwise vortices. Slices of streamwise vorticity at various streamwise locations, combined with vorticity strength distributions, have been presented to study the development of streamwise vortices. The counter-rotating vortices are divided into the crest-induced streamwise vortices (CSVs) and trough-induced streamwise vortices (TSVs). A streamwise vortex pair formed from a part of the CSV sheets behind troughs, is gradually entrained by the TSV pair along the streamwise direction. In addition, the tubercles with a smaller wavelength result in higher streamwise vorticity strength with which the streamwise vortices interact with the flow separation more sufficiently and delay the separation to a greater extent.

4

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.