Improvement of Castability and Quality of Continuously Cast Steel.

Janke, Dieter; Ma, Zhongting; Valentin, P.; Heinen, Anddreas

doi:10.2355/isijinternational.40.31

Cited by 62 publications

(50 citation statements)

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“…The inclusion shapes shown in Figure 8 are not similar to what is observed in Al-Ca-O inclusions that are liquid, because those inclusions, primarily in the form of CaO.Al 2 O 3 , would tend to have a globular shape after proper calcium treatment. [6,19,20] Therefore, from the current results it seems that inclusions that were liquid (viscous) were not formed under the experimental conditions in this study.…”

Section: A the Effect Of Ti/al Ratio On Inclusion Chemistrycontrasting

confidence: 57%

“…The titanium content in the melt was increased even more, such that Al 2 TiO 5 was stable in the melt (AlTi- [17][18][19], by increasing the Ti/Al ratio to 15/1 (by establishing 0.060 wt pct titanium content and 0.004 wt pct of dissolved aluminum content; see Figure 2). Subsequently, the Ti/Al ratio was raised to 75/1 by establishing a titanium content of 0.300 wt pct and an aluminum content of 0.004 wt pct, such that the stable phase in the melt was Ti 3 O 5 (AlTi-20-22).…”

Section: B Deoxidation In Regions Where Al 2 O 3 Is Not Stablementioning

confidence: 95%

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Transient Behavior of Inclusion Chemistry, Shape, and Structure in Fe-Al-Ti-O Melts: Effect of Titanium/Aluminum Ratio

Nuhfer

Sridhar

2009

Metall Mater Trans B

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During ladle processing of interstitial-free (IF) steel melts, it is possible for transient titaniumcontaining oxides to be formed if the local titanium/aluminum (Ti/Al) ratio is locally and temporarily increased after aluminum killing. The phase stability diagrams suggest that if the Ti/Al ratio is increased, then Al 2 TiO 5 and/or a liquid Al-Ti-O region can become stable, and eventually at even higher Ti/Al ratios, Ti 3 O 5 becomes stable. In this study, the Ti/Al ratio was successively altered to investigate (1) how the inclusions evolved after titanium addition to aluminum-killed iron melts and (2) whether the inclusions present after sufficient time were those predicted by thermodynamics. When the Ti/Al ratio was maintained at 1/4, such that Al 2 O 3 is the only thermodynamically stable oxide, the results show that transient titaniumcontaining oxides exist temporarily after titanium addition, but with time, the predominant inclusion was Al 2 O 3 , which would generate little shape change and produce transient stage inclusions with less titanium contents. When the Ti/Al ratio was increased to 1/1 (Al 2 O 3 still being the only thermodynamically stable oxide), the results show a more distinct increase in the titanium content of the transient inclusions. The transient reaction was, in this case, accompanied by an irreversible shape change from spherical to irregular inclusions. When the Ti/Al ratio in the melt was increased to 15/1 within the Al 2 TiO 5 stable phase region, the inclusion population evolved from spherical-dominant ones to irregular ones. It was found that the final inclusion chemistry has more titanium but less aluminum content compared with the expected from the Al 2 TiO 5 chemistry. Besides, the transmission electron microscopy (TEM) results showed the existence of Ti 2 O. When the Ti/Al ratio in the melt was increased such that Ti 3 O 5 is the thermodynamically stable inclusion (Ti/Al ratio of 75/1 or ¥), the inclusions evolved after titanium addition toward TiO x inclusions, which is accompanied by a shape change from spherical to irregular. The TEM results revealed and confirmed the existence of metastable Ti 2 O besides the thermodynamically stable Ti 3 O 5 , and it was consistent with the results based on oxidation studies of thin layers of titanium with Al 2 O 3 substrate. It was discovered that Ti 2 O has the tendency of transforming into the thermodynamically stable phase Ti 3 O 5 under certain conditions.

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Section: A the Effect Of Ti/al Ratio On Inclusion Chemistrycontrasting

confidence: 57%

Section: B Deoxidation In Regions Where Al 2 O 3 Is Not Stablementioning

confidence: 95%

Transient Behavior of Inclusion Chemistry, Shape, and Structure in Fe-Al-Ti-O Melts: Effect of Titanium/Aluminum Ratio

Nuhfer

Sridhar

2009

Metall Mater Trans B

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“…Alumina has a high melting point and tends to cluster and clog the casting nozzles. 74 24 The formation of low melting liquid films and shrinkage strains during the last stage of solidification often causes hot cracking in some castings. Some alloying elements have a tendency to widen the liquid-solid two-phase zone, leading to a higher tendency for segregation and, thus, hot cracking.…”

Section: Effect Of Al Si Co and Pmentioning

confidence: 99%

Ultrahigh strength steel wires processed by severe plastic deformation for ultrafine grained microstructure

Li¹,

Virta²

2011

Materials Science and Technology

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A comprehensive review of recent literature on high strength, fine grained steels has been conducted. While relevant technologies in alloy design, processing and heat treating are included in the present review, the emphasis has been on high carbon steel wire processing technology that can be achieved with 'conventional' wire rolling and drawing processes. The thermomechanical processing of a pearlitic microstructure, followed by cold drawing, is recommended as the process of choice to efficiently produce an ultrafine grained ferrite-cementite microstructure for ultrahigh strength, ultrahigh carbon steel wires.

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“…Calcium alloy is a popular modifier for sulfide spheroidization and alumina liquefaction. [6][7][8][9] In Ca-treated Al-killed steel, complex sulfide inclusions are often observed; among these inclusions, single-phase (Mn,Ca)S solid solution and oxide-sulfide duplex, which consists of an oxide core and a sulfide ring, can be detected. [10][11][12][13] In the many theoretical investigations of inclusion formation in Ca-treated Al-killed steel, the activity of CaS associated with the oxide phase has often been assumed to be a constant, such as 1, [14] because of the very low solubility of CaS (2 to 5 wt pct) in calcium aluminate at 1823 K (1550°C) [15] and the lack of MnS inclusion in general structural steel above the liquidus temperature.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamics of Complex Sulfide Inclusion Formation in Ca-Treated Al-Killed Structural Steel

Guo

Chen

et al. 2016

Metall Mater Trans B

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Controlling the morphology of the sulfide inclusion is of vital importance in enhancing the properties of structural steel. Long strip-shaped sulfides in hot-rolled steel can spherize when, instead of the inclusion of pure single-phase MnS, the guest is a complex sulfide, such as an oxide-sulfide duplex and a solid-solution sulfide particle. In this study, the inclusions in a commercial rolled structural steel were investigated. Spherical and elongated oxide-sulfide duplex as well as single-phase (Mn,Ca)S solid solution inclusions were observed in the steel. A thermodynamic equilibrium between the oxide and sulfide inclusions was proposed to understand the oxide-sulfide duplex inclusion formation. Based on the equilibrium solidification principle, thermodynamic discussions on inclusion precipitation during the solidification process were performed for both general and resulfurized structural steel. The predicted results of the present study agreed well with the experimental ones.

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Improvement of Castability and Quality of Continuously Cast Steel.

Cited by 62 publications

References 0 publications

Transient Behavior of Inclusion Chemistry, Shape, and Structure in Fe-Al-Ti-O Melts: Effect of Titanium/Aluminum Ratio

Transient Behavior of Inclusion Chemistry, Shape, and Structure in Fe-Al-Ti-O Melts: Effect of Titanium/Aluminum Ratio

Ultrahigh strength steel wires processed by severe plastic deformation for ultrafine grained microstructure

Thermodynamics of Complex Sulfide Inclusion Formation in Ca-Treated Al-Killed Structural Steel

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