Microstructure and Cleanliness of Rapidly Solidified Steels

Volkova, Olena; Heller, Hans‐Peter; Janke, Dieter

doi:10.2355/isijinternational.43.1724

Cited by 21 publications

(15 citation statements)

References 19 publications

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“…[19] Figure 2 shows the secondary dendrite arm spacing (SDAS) as a function of the cooling rate and a typical image of the steel surface in the CSLM where the solidifying steel secondary dendrite arm tips can be seen; as the dendrite grow approximately parallel to the steel surface, the spacing between the observed tips gives the SDAS. [19] The SDAS with cooling rate data has been compared to the literature [20] for a similar steel (0.17C-1.5Mn-0.4Si) and good agreement between the two can be seen in Figure 2. The obtained relationship between SDAS and cooling rate (CR) from this work is given as follows:…”

Section: A Confocal Microscopymentioning

confidence: 88%

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Near Net Shape Casting: Is It Possible to Cast Too Thin?

Slater

Davis

2020

Metall Mater Trans B

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With increased efforts across the steel industry to produce steel in more economical ways, interest in near net shape casting has increased. Although much has been reported on the production of exotic alloys via these methods, to make the investment in new casting equipment, capability to produce current high value steels by these methods would derisk the capital expenditure. This study assesses the production of a dual phase steel (DP800) by belt casting and compared to that of conventional continuous casting. Although a drop in yield and tensile strength was seen in the belt cast-produced material, the increased elongation allowed for a comparable/improved UTS × elongation factor. A combination of in situ dendrite measurements, thermal modeling, and lab-scale belt casting has allowed insight into the relationship between cast thickness and final band spacing. The inherent lack of deformation of near net shape casting results in coarser band spacing and is not accounted for by the refinement of the secondary arm spacing caused by the faster solidification rates. This limits the strength achievable for a given martensite volume fraction. This has been predicted across the full range of casting thicknesses (1 to 230 mm) and good agreement has been shown with experimental results.

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Section: A Confocal Microscopymentioning

confidence: 88%

“…Although many broader equations exist for predicting SDAS, such as those that include compositional influences (particularly carbon), [20,21] here, a simplified approximation has been used that will apply for this specific alloy across the full range of cooling rates tested.…”

Section: A Confocal Microscopymentioning

confidence: 99%

Near Net Shape Casting: Is It Possible to Cast Too Thin?

Slater

Davis

2020

Metall Mater Trans B

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“…After analyzing the ladle and tundish samples, the compositions of inclusions were MnOAESiO 2 AEAl 2 O 3 (corundum) inclusions and small amounts of Al 2 O 3 AE MgOAEMnO (spinel) inclusions. Volkova et al [5] studied the inclusion number and size with cooling rate in various grade steels, including TRIP steels, and presented empirical equations that related the inclusion size to the cooling rate. Liu et al [6] used mathematical modeling to simulate the precipitation of a sulfide inclusion on preexisting oxide particles in a Fe-Si alloy.…”

Section: Introductionmentioning

confidence: 99%

“…However, strategies have been developed to alter inclusions such that they can be used to control phase transformations to improve mechanical and physical properties in steel. [1][2][3] The published work [4][5][6][7] on inclusions is limited in the case of high silicon-bearing steels, such as oriented and nonoriented electrical steels and transformation-induced plasticity (TRIP) steels, even though the microphase structure related to inclusions is complex and important. Choudhary et al [4] studied the inclusions in Mn-Si deoxidized steel from the viewpoint of nozzle clogging.…”

Section: Introductionmentioning

confidence: 99%

The Morphology and Chemistry Evolution of Inclusions in Fe-Si-Al-O Melts

Kwon

Choi

Sridhar

2011

Metall Mater Trans B

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This study aims to elucidate the process of inclusion precipitation in Fe-Si and Fe-Si-Al melts. Deoxidation experiments were carried out in a vacuum induction furnace (VIF) at 1873 K (1600°C). In the Si-deoxidation experiments, spherical SiO 2 of 1~2 lm diameter was dominant. When 3 wt pct Si and 300 ppm Al were added, such that Al 2 O 3 and mullite were thermodynamically stable, the resulting inclusions depended on the addition sequence. When aluminum was added before silicon, spherical aluminum oxides were dominant after the Al addition, but after the Si addition, the number and size of alumina decreased and Al-Si oxides and mullite appeared with increasing time. When silicon was added before aluminum, spherical SiO 2 was dominant after the Si addition, but after the Al addition, spherical and polygonal alumina inclusions were dominant. When Al/Si was added simultaneously, polygonal alumina inclusions were dominant initially, but with time, Al-Si oxide and mullite inclusions increased in numbers. If the Al amount in the Al/Si addition was increased to 600 ppm, only alumina was found. This study shows how, under similar thermodynamic conditions, the transient evolution of inclusions in iron melts in the Si-Al-O system differ depending on the alloy addition sequence.

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“…The diffusion distance is assumed being half of the secondary dendritic arm spacing (SDAS). For low carbon steels SDAS can be predicted through Equation

S D A S = 148 {\dot{T}}^{- 0.38}

where

\dot{T}

is the cooling rate.…”

Section: Introductionmentioning

confidence: 99%

Implications of Accelerated Solidification Rates Seen in Belt Casting on Precipitation in Nb Bearing Steels

Slater

Kostryzhev

Marenych

et al. 2017

steel research int.

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High temperature confocal microscopy (using cooling rates of 1 and 20 C s À1 ) has been used in conjunction with segregation modeling (for cooling rates of 0.1-100 C s À1 ) to understand the implications that high cooling rates, representative of that seen for belt casting, has on compositional inhomogeneity and precipitation in high strength low alloy steels. Due to the increased level of segregation (and reduced back diffusion) precipitates are predicted, and shown, to form in the interdendritic solute rich regions at temperatures higher than would be expected under equilibrium conditions at the higher cooling rate. This results in a larger volume fraction of precipitates in samples held at 1000 C after being cooled at 20 C s À1 compared to those cooled at 1 C s À1 .

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Microstructure and Cleanliness of Rapidly Solidified Steels

Cited by 21 publications

References 19 publications

Near Net Shape Casting: Is It Possible to Cast Too Thin?

Near Net Shape Casting: Is It Possible to Cast Too Thin?

The Morphology and Chemistry Evolution of Inclusions in Fe-Si-Al-O Melts

Implications of Accelerated Solidification Rates Seen in Belt Casting on Precipitation in Nb Bearing Steels

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