Austenite Grain Refining of As-cast Bloom Surface by Reduction of Oscillation Mark Depth

Ohba, Yasuhide; Kitade, Shinichi; Takasu, Ichiro

doi:10.2355/isijinternational.48.350

Cited by 6 publications

(5 citation statements)

References 18 publications

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“…slab surface. We focus on a peritectic carbon steel with 0.2mass% carbon concentration, since the as-cast γ grain structure in this steel is known to exhibit quite coarse and columnar structure [10]. Furthermore, we investigate 0.35 mass% carbon steel in order to support the validity of our findings.…”

Section: Introductionmentioning

confidence: 99%

Formation mechanism of coarse columnar γ grains in as-cast hyperperitectic carbon steels

et al. 2011

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The formation mechanism of as-cast coarse columnar γ grain (CCG) structure in hyperperitectic carbon steels is investigated by means of rapid unidirectional solidification method. This method realizes the cooling conditions similar to those in the vicinity of practical continuously cast slab surface. The microstructural observation of the quenched samples indicates that the CCG structure develops from the mold side along the direction of the temperature gradient. In the solidifying samples, fine columnar γ grains (FCGs) always exist ahead of the CCG region. Instead of continuous growth into the large grains, the FCGs always shrink and vanish due to the growth of the CCGs initially formed near the mold side. Therefore, the grain size at a fixed point of the ingot discontinuously changes from the FCG to the CCG. The validity of this process was supported by numerical analyses. This finding is in marked contrast to the assumption made in the conventional grain growth analysis on the CCG structure.

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Section: Introductionmentioning

confidence: 99%

Formation mechanism of coarse columnar γ grains in as-cast hyperperitectic carbon steels

et al. 2011

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“…Percebe-se melhor ajuste aos resultados obtidos por Schwerdtfeger [4]. Observa-se que os estudos de Ohba [5] e Normanton [7] obtiveram inclinações similares, contudo com valores mais elevados. Na figura 10 é mostrada a fotografia obtida no microscópio ótico com ampliação original de 12,5X o gancho na base da marca de oscilação.…”

Section: Resultsunclassified

Avaliação Do Efeito Da Oscilação Do Molde Sobre a Qualidade De Placas

Reis¹,

Cunha²,

Mendonça³

2017

Anais Do Seminário De Aciaria, Fundição E Metalurgia De Não-Ferrosos

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ResumoA solidificação do aço no molde é determinante para a qualidade superficial da placa, considerando que os principais defeitos tendem a se formar nos primeiros estágios de formação da pele. Assim, diversos parâmetros do processo que afetam a solidificação no molde devem ser considerados e um deles é a oscilação do molde. A partir de amostras da face estreita de placas obtidas no processo industrial, duas técnicas para avaliar o efeito da oscilação foram desenvolvidas com base em perfilometria a laser e metalografia. Em relação à perfilometria a laser, desenvolveuse um método de análise da profundidade das marcas de oscilação. Foi comprovada a correlação da profundidade média dessas marcas com o tempo de estripamento negativo. A segunda técnica refere-se ao ataque metalográfico à base de ácido pícrico, que se mostrou eficiente para visualização, via microscopia ótica, do gancho na base da marca de oscilação. Bolhas de argônio e partículas de pó fluxante podem ser aprisionadas na região do gancho de oscilação, e eventualmente ocasionar defeitos nos produtos laminados. O uso das técnicas apresentadas nesse estudo forneceu subsídios à tomada de ações visando a diminuição da profundidade do gancho e da marca de oscilação, resultando em melhoria da qualidade superficial das placas produzidas. Palavras-chave: Oscilação do molde; Profundidade da marca; Gancho de oscilação. EVALUATION THE EFFECT OF OSCILLATION MOLD ON SLAB QUALITY AbstractMold Steel solidification is very important for slab surface quality, considering that the main defect happens during the first stages of shell formation. Thus, many process parameters which influence mold steel solidification should be considered, and one of them is the mold oscillation. Samples of the narrow side of the slabs were obtained from the industrial process and two techniques were developed to evaluate oscillation effect laser perfilometry and mettallography. Regarding to laser perfilometry, it was developed an analysis method of oscillation mark depth. It was proven the correlation of the average oscillation mark depth with the negative strip time. The second technique regards to metallography etching based on picric acid, which showed useful to view, by optical microscopy, the hook at the base of oscillation mark. Argon bubbles and flux particles can be captured at oscillation hook region, and eventually cause defects on rolled products. The use of techniques presented in this study provided subsidies for decision making aiming the reduction of oscillation mark depth and hook, resulting in surface quality improvement of slabs produced.

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“…Calculated versus experimental [22,26,45,85,87,90,98,[148][149][150][151][152][153][154][155][156][157][158][159][160] SDAS in carbon, low-alloyed, and high-alloyed steels. [10,[161][162][163][164][165][166][167][168][169] austenite grain sizes in low-alloyed steels. indicating an appropriate general validity of IDS simulations for different types of steels.…”

Section: Discussionmentioning

confidence: 99%

“…A similar optimization was made to calculate the austenite grain growth during the cooling process after solidification. Figure 20 shows a comparison of the calculated and measured [10,[161][162][163][164][165][166][167][168][169] austenite grain sizes in several low-alloyed steels. Again, due to the uncertainty of measuring good average values for the grain sizes, the obtained agreement can be considered reasonable.…”

Section: Microstructure Datamentioning

confidence: 99%

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Simulation of the Solidification and Microstructural Evolution in Steel Casting Processes Using the InterDendritic Solidification Tool

Miettinen

Somani

Visuri

et al. 2022

steel research int.

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InterDendritic Solidification (IDS) is a thermodynamic-kinetic software combined with a microstructure tool developed to simulate the nonequilibrium solidification (non-EQS) of steels. Herein, its main calculation module, solidification (SOL), is introduced, and some essential results of that module, such as the formation of ferrite and austenite in different types of steels during their solidification, and the formation and dissolution of precipitates during subsequent cooling and heating processes, respectively, following solidification, are presented. The non-EQS is compared with equilibrium and poor-kinetics solidification to demonstrate the effect of kinetics on the results using finite solute diffusion and microstructure data. The poor-kinetics solidification is comparable with the modified Scheil simulation ignoring the solid-state diffusion of slowly moving metallic elements. A particular emphasis is made on demonstrating how to use a postprocessing treatment to control the residual ferrite amounts in stainless steels and the extent of precipitation in particular steel. In this context, the phenomena occurring behind the results are discussed. Finally, to validate the simulations of the SOL module, its calculations are compared with numerous solidification measurements, such as the liquidus and solidus temperatures of different steels and the residual ferrite amounts in stainless steels.

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Austenite Grain Refining of As-cast Bloom Surface by Reduction of Oscillation Mark Depth

Cited by 6 publications

References 18 publications

Formation mechanism of coarse columnar γ grains in as-cast hyperperitectic carbon steels

Formation mechanism of coarse columnar γ grains in as-cast hyperperitectic carbon steels

Avaliação Do Efeito Da Oscilação Do Molde Sobre a Qualidade De Placas

Simulation of the Solidification and Microstructural Evolution in Steel Casting Processes Using the InterDendritic Solidification Tool

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