Refinement of As-cast Austenite Microstructure in S45C Steel by Titanium Addition

Ohno, Munekazu; Matsuura, Kiyotaka

doi:10.2355/isijinternational.48.1373

Cited by 24 publications

(18 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is known that in steels with higher carbon concentrations, e.g. 0.45mass% carbon steel, columnar γ grains form in the vicinity of the mold wall [8,9]. However, to the best of our knowledge, the variations of the morphology and size of as-cast γ structures with the carbon concentration have not been scrutinized yet.…”

Section: Introductionmentioning

confidence: 93%

Transition of solidification mode and the as-cast γ grain structure in hyperperitectic carbon steels

2012

Self Cite

View full text Add to dashboard Cite

Formation processes of as-cast γ grain structures during casting of hyperperitectic carbon steels with 0.15-0.45 mass% carbon concentrations have been studied by means of a rapid unidirectional solidification technique. In steels with 0.15-0.41 mass% carbon concentrations, coarse columnar γ grains (CCG) with a minor axis diameter of 1-3mm developed along the direction of temperature gradient. In a steel with 0.38 mass% carbon, importantly, columnar γ grains (CG) whose minor axis diameter is less than 500 μm form before the formation of CCG and the grain structure discontinuously changes from CG to CCG. The fraction of CG region increases with increase in the carbon concentration. In the samples with the carbon concentration higher than 0.43 mass%, the as-cast structure consists of CG over almost the entire ingots. Analyses on a relation between γ grain and dendrite structures and their crystallographic orientations indicate that the formation of CG originates from the primary solidification of γ phase instead of δ phase. This is supported by numerical analysis on the dendrite growths.

show abstract

Section: Introductionmentioning

confidence: 93%

Transition of solidification mode and the as-cast γ grain structure in hyperperitectic carbon steels

2012

Self Cite

View full text Add to dashboard Cite

show abstract

“…A rectangular area on the sectioned surface, extending from one mold side to the other mold side in the thickness direction, was selected for the microstructural observation. It is allowed to take into account only the one-dimensional heat flow in the thickness direction on this selected area [15]. This area was polished and etched with 3% nital and Oberhoffer's solutions to observe the as-cast  grain and dendrite structures, respectively.…”

Section: Experimental and Numerical Proceduresmentioning

confidence: 99%

A critical condition for the formation of a coarse columnar γ grain structure in a peritectic solidified carbon steel

2013

Self Cite

View full text Add to dashboard Cite

The formation of coarse columnar austenite grain (CCG) structure is one of the serious problems in continuous casting processes of peritectic solidified carbon steels.In this study, a guiding principle for avoidance of the CCG formation is developed. The critical condition of the CCG formation recently put forward based on phase-field simulations, which is given by a balance between the cooling condition and the growth rate of the CCG, is first reexamined and modified by considering effect of liquid phase during the CCG formation. Then, the validity of this critical condition is investigated by three different casting experiments combined with heat conduction analyses. From comparison between the cooling conditions and the resulting microstructural changes, the validity of the critical condition is successfully demonstrated.

show abstract

“…3,6,7) It has been reported that the nucleation undercooling of d-Fe on Ti(C, N) is just 1.8°C, 4) which indicates a high ability of the…”

Section: Introductionmentioning

confidence: 99%

“…Formation of fine equiaxed g grain structure is of critical importance in steel industries to prevent surface cracking and harmful effects on mechanical properties at high temperatures originating from the coarse columnar structure. 1,2) In our recent study on the casting process of a hyperperitectic steel, 3) it has been demonstrated that the addition of a certain amount of titanium results in fully equiaxed fine g grain structure over the whole cast ingot. The microstructural observations indicated that the formation of the equiaxed g-grain structure should be essentially related to the Columnar-to-Equiaxed Transition (CET) of ferrite (d)-dendrite structure.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis on Columnar-to-equiaxed Transition of δ-Ferrite Dendrite in Carbon Steel Induced by Titanium Carbonitride Particles

Ohno

Matsuura

2009

ISIJ Int.

Self Cite

View full text Add to dashboard Cite

Dendrite growth simulations have been performed to analyze Columnar-to-Equiaxed Transition (CET) of dferrite dendrite structure triggered by fine particles of a primary Ti(C, N) crystal. The CET position estimated by Hunt's criterion and the present simulation indicated that the existence of a large number of the Ti(C, N) particles gives rise to the CET of the dendrite structure even in the vicinity of the mold wall under the present casting condition. Furthermore, the capability of the Ti(C, N) leading to the CET was discussed in the light of the different number of Ti(C, N) particles and the different thickness of cast ingot. It was shown that a sufficient number of Ti(C, N) leads to the formation of fully equiaxed dendrite structure irrespective of the ingot thickness.KEY WORDS: columnar-to-equiaxed transition; hyperperitectic steel; titanium carbonitride; casting; solidification; simulation; dendrite structure.Ti(C, N) giving rise to the CET of d dendrite solidification. When the values of N 0 and DT N are given, one can predict the occurrence of the CET based on the relation between G and DT t (or the growth velocity of columnar dendrite described as a function of DT t , V(DT t )) within the Hunt's model. It should be pointed out that G and DT t (and V) are essentially time-dependent quantities during the casting process and the analysis of the CET requires such a time dependency to be addressed in detail.The main objective of this study is twofold; one is to substantiate the occurrence of the CET of d dendrite morphology induced by the primary Ti(C, N) in the light of the time-dependent behavior of G-V relation during the casting process and the other is to analyze the capability of Ti(C, N) giving rise to the CET under various casting conditions. To this end, we carry out a columnar dendrite growth simulation describing the time-dependent behavior of G-V relation. The input parameters for the simulation are obtained from the results of casting experiment. The relation between our calculated results and the Hunt's criterion suggests that the Ti(C, N) particles induce the CET of d dendrite morphology in the vicinity of the side surface of the ingot, which is fairly consistent with the metallographic observations. Finally, the capability of the Ti(C, N) giving rise to the CET is discussed in terms of several solidification conditions with the different number of Ti(C, N) particles and the different cooling conditions. In the conventional continuous casting process of the steel, the slab thickness is one of parameters to change the cooling rate of the cast. Therefore, we will discuss the occurrence of the CET in the different cast thickness. One will see that a sufficient number of the Ti(C, N) particles lead to the formation of the equiaxed dendrite over almost the entire cast ingot irrespective of the cast thickness. ExperimentalThe casting experiments were carried out for samples of S45C steel with and without titanium addition. The S45C steel employed in this study consists of 0.436 wt% C, 0.204 wt% Si, 0...

show abstract

Refinement of As-cast Austenite Microstructure in S45C Steel by Titanium Addition

Cited by 24 publications

References 18 publications

Transition of solidification mode and the as-cast γ grain structure in hyperperitectic carbon steels

Transition of solidification mode and the as-cast γ grain structure in hyperperitectic carbon steels

A critical condition for the formation of a coarse columnar γ grain structure in a peritectic solidified carbon steel

Numerical Analysis on Columnar-to-equiaxed Transition of δ-Ferrite Dendrite in Carbon Steel Induced by Titanium Carbonitride Particles

Contact Info

Product

Resources

About