Optimization of Melt Treatment for Austenitic Steel Grain Refinement

Lekakh, Semen Naumovich; Ge, Jun; Richards, Von; O’Malley, Ronald J.; TerBush, Jessica R.

doi:10.1007/s11663-016-0832-5

Cited by 27 publications

(10 citation statements)

References 20 publications

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“…According to the available inoculation theories [2,5], particles can act as nuclei only if they can survive or precipitate above the liquidus temperature of the matrix alloy; therefore, out of the above particles only, Ti(CN) and the oxide particles are possible candidates to act as nuclei for austenitic grains. SEM images illustrating the shape and size of oxide and Ti(CN) particles observed in Hadfield steel samples alongside their EDS spectrums and nominal compositions are shown in Figure 3.…”

Section: The Effect Of Oxide Particlesmentioning

confidence: 99%

“…It is known that Ti(CN) precipitates in the melt at a temperature of 1520 °C, which is above the liquidus and below the oxide precipitation temperature (above 1600 °C depending on the type of oxide) [6]. Ti(CN) also has the tendency to precipitate and grow on the oxide particles [5,6]. The precipitation of Ti(CN) on the oxides restrained any contact of the oxide particle's surface with the steel melt.…”

Section: The Effect Of Oxide Particlesmentioning

confidence: 99%

“…In another study performed by Lekakh et al [5], it was observed that a sequential addition of Ca, and Al-Mg followed by Ti, produced a finer microstructure in stainless austenitic steels when compared to other sequential addition combinations of the same elements. The aim behind the most successful deoxidation practice was to create a higher density number of spinel particles for TiN to precipitate on and thus a higher density number and smaller size of TiN particles for austenite to precipitate on.…”

Section: Introductionmentioning

confidence: 95%

See 2 more Smart Citations

The Influence of Deoxidation Practice on the As-Cast Grain Size of Austenitic Manganese Steels

Siafakas

Matsushita

Lauenstein

et al. 2017

Metals

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Abstract:The effect of in-situ precipitating particles on the grain size of Al-Ti-treated and untreated Hadfield steel cast in a pilot scale environment was studied. Hadfield steel was melted in an induction furnace and cast in Y-Block samples. Light Optical Microscopy (LOM) and the intercept method were utilized for the grain size measurements. Additionally, Thermo-Calc Software TCFE7 Steels/Fe-alloys database version 7 was used for thermodynamic equilibrium calculations of the mole fraction of particles. The planar disregistry values between the austenite and the precipitating particles were calculated. It was observed that increasing oxide content in samples with low Ti(CN) content resulted in a finer microstructure, while increasing the Ti(CN) content under similar oxide content levels led to a coarser microstructure. The potency of each type of particle to nucleate austenitic grains was determined. Spinel (MnAl 2 O 4 , MgAl 2 O 4 ) particles were characterized as the most potent, followed by olivine (Mn 2 SiO 4 ), corundum (Al 2 O 3 , TiO 2 ), and finally Ti(CN), the least potent particle.

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Section: The Effect Of Oxide Particlesmentioning

confidence: 99%

Section: The Effect Of Oxide Particlesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

See 1 more Smart Citation

The Influence of Deoxidation Practice on the As-Cast Grain Size of Austenitic Manganese Steels

Siafakas

Matsushita

Lauenstein

et al. 2017

Metals

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“…The non-metallic spinel phase Al 2 O 3 -MgO were found in many TiN precipitates. It has been reported that spinel can act as inoculant for Ti(CN) [20,21].…”

Section: Discussionmentioning

confidence: 99%

Cast Structure in Alloy A286, an Iron-Nickel Based Superalloy

Frisk

Andersson

Rogberg

2019

Metals

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The structure and segregation of a continuously cast iron-nickel based superalloy were investigated. Cross-sectional samples were prepared from the central section of a 150 × 150 mm square billet. The microporosity was measured from the surface to the center and theoretical conditions for pore formation were investigated. A central porosity, up to 10 mm in width, was present in the center of the billet. The measured secondary arm spacing was correlated with a calculated cooling rate and a mathematical model was obtained. Spinel particles were found in the structure, which acted as inoculation points for primary austenite and promoted the formation of the central equiaxed zone. Titanium segregated severely in the interdendritic areas and an increase of Ti most likely lead to a significant decrease in the hot ductility. Precipitates were detected in an area fraction of approximately 0.55% across the billet, which were identified as Ti(CN), TiN, η-Ni3Ti, and a phosphide phase.

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“…[28] Thermodynamic software utilizing the fundamental principle of Gibbs free energy minimization has been used for analyzing various steelmaking processes and experimental reports support its reliability. [29][30][31][32][33][34][35][36] Common areas in steelmaking that have employed thermodynamic studies include refining and non-metallic inclusion formation in the melt, as well as precipitate formation in the solid. The feasibility of thermodynamic studies for a large volume of processed liquid steel relates to (i) intensive mixing during sufficient time and (ii) high melting temperature, both factors that allow the chemical reactions to proceed close to equilibrium.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Prediction and Experimental Verification of Multiphase Composition of Scale Formed on Reheated Alloy Steels

Osei

Lekakh

O’Malley

2020

Metall Mater Trans B

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The structure, phase, and composition of scale formed on a continuously cast steel slab during reheating depend on intrinsic factors (steel chemistry, microstructure, and as-cast surface condition) and extrinsic parameters (temperature, time, composition, and velocity of combustion gas atmosphere). The scale that forms on a slab normally has several layers with differing compositions and phases and knowledge of this scale structure is important in subsequent descaling and hot rolling processing steps. Formation of multiphase scale structures on steel during high temperature oxidation in reheat furnace proceeds according to a local thermodynamic equilibrium, while thickness of layers depends on kinetic conditions (mostly by diffusion). In this study, the local thermodynamic equilibrium conditions through the scale layer were simulated using different oxygen/steel ratios, which mimicked the conditions for scale formation at the external, internal, and sublayer oxide region at metal/scale boundary. Experiments were performed in a simulated combustion atmosphere using typical industrial reheat time/temperature conditions. The phases that developed in layered scale structure were documented using SEM/EDX and Raman spectroscopy. The predicted scale compositions and phases were in good agreement with the experimental results for studies with Mn and Si-alloyed carbon steel, Cr-alloyed ferritic, and Cr, Ni-alloyed austenitic steels.

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Optimization of Melt Treatment for Austenitic Steel Grain Refinement

Cited by 27 publications

References 20 publications

The Influence of Deoxidation Practice on the As-Cast Grain Size of Austenitic Manganese Steels

The Influence of Deoxidation Practice on the As-Cast Grain Size of Austenitic Manganese Steels

Cast Structure in Alloy A286, an Iron-Nickel Based Superalloy

Thermodynamic Prediction and Experimental Verification of Multiphase Composition of Scale Formed on Reheated Alloy Steels

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