A novel approach for interpreting the solidification behaviour of peritectic steels by combining CSLM and DSC

Hechu, Kateryna; Slater, Carl; Santillana, Begoña; Clark, Samuel J.; Sridhar, Seetharaman

doi:10.1016/j.matchar.2017.09.013

Cited by 33 publications

(8 citation statements)

References 27 publications

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“…It can be seen that the cooling under an argon atmosphere gave a liquidus much lower than that of predicted equilibrium solidification, which was expect as nucleation was limited from the free surface (the high purity of the atmosphere means that no inclusions or surface oxides were observed) and; therefore, a large undercooling was required locally before solidification was seen. This is consistent with previous work on the CSLM, where the smooth crucible surface and small sample size can reduce the chance of a nucleation event significantly [20]. Under a CO 2 atmosphere, the newly formed surface oxide can act as nucleation sites, and this minimises the undercooling required to a point where the liquidus matches very closely to the equilibrium predicted value (it is also possible some carbon was removed during oxidation, which would increase the liquidus; this is expected to be a minor influence as oxygen is predicted to more favourably bond with Al and Si, compared to forming CO (Factsage 7.2, Aachen, Germany)).…”

Section: Resultssupporting

confidence: 92%

“…As the samples' surfaces changed emissivity, both during solidification and in the presence of a surface product, the stated temperatures in this paper refer to this calibrated point, and was, hence, why the distance away from the sample was limited to 500 µm. This method has shown very good agreement previously, where the impact of any thermal lag was shown to be negligible using differential calorimetry [19,20]. Therefore, the readings taken from the surface act to provide information on when events occur, rather than providing a direct temperature reading itself.…”

Section: Methodsmentioning

confidence: 67%

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Characterisation of the Solidification of a Molten Steel Surface Using Infrared Thermography

Slater

Hechu

Davis

et al. 2019

Metals

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Infrared thermography provides an option for characterising surface reactions and their effects on the solidification of steel under different gas atmospheres. In this work, infrared thermography has been used during solidification of Twin Induced Plasticity (TWIP) steel in argon, carbon dioxide and nitrogen atmospheres using a confocal scanning laser microscope (CSLM). It was found that surface reactions resulted in a solid oxide film (in carbon dioxide) and decarburisation, along with surface graphite formation (in nitrogen). In both cases the emissivity and, hence, the cooling rate of the steel was affected in distinct ways. Differences in nucleation conditions (free surface in argon compared to surface oxide/graphite in carbon dioxide/nitrogen) as well as chemical composition changes (decarburisation) affected the liquidus and solidus temperatures, which were detected by thermal imaging from the thermal profile measured.

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Section: Resultssupporting

confidence: 92%

Section: Methodsmentioning

confidence: 67%

Characterisation of the Solidification of a Molten Steel Surface Using Infrared Thermography

Slater

Hechu

Davis

et al. 2019

Metals

Self Cite

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“…The solidus and liquidus temperatures and another transformation temperatures of iron, steel and other alloys can be determined, for example, by the use of differential thermal analysis (DTA), with the help of differential scanning calorimetry (DSC), or with the use of thermal-derivative analysis (TDA) [1,21,[26][27][28][29][30]. However, when considering the dimensions and possible chemical and structural inhomogeneity of the analyzed sample, it is very difficult to precisely determine the solidus temperature with the use of the sophisticated DTA and DSC methods [1,7,18,28,31]. Won and Thomas [32] reported that during the solidification processes, an important role is also played by microsegregation.…”

Section: Introductionmentioning

confidence: 99%

The Relationship between Nil-Strength Temperature, Zero Strength Temperature and Solidus Temperature of Carbon Steels

Kawulok

Schindler

Smetana

et al. 2020

Metals

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The nil-strength temperature, zero strength temperature and solidus temperature are significant parameters with respect to the processes of melting, casting and welding steels. With the use of physical tests performed on the universal plastometer Gleeble 3800 and calculations in the IDS software, the nil-strength temperatures, zero strength temperatures and solidus temperatures of nine non-alloy carbon steels have been determined. Apart from that, solidus temperatures were also calculated by the use of four equations expressing a mathematical relation of this temperature to the chemical composition of the investigated steels. The nil-strength and zero strength temperatures and the solidus temperatures decreased with increasing carbon content in the investigated steels. Much higher content of sulfur in free-cutting steel resulted in a decrease of all the temperatures investigated. The zero strength temperatures determined by calculation in the IDS software during solidification were approximately 43–85 °C higher than the nil-strength temperatures determined experimentally during heating of the investigated steels. The linear dependence of experimentally measured nil-strength temperature on the calculated zero strength temperature for the investigated steels was determined. Based on regression analyses, there were determined mathematical relations which described with high accuracy a linear dependence of the nil-strength and zero strength temperatures on the solidus temperature of the investigated steels.

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“…The ferritic grain coarsening and the precipitation of carbides result in decreased ductility between 800 and 900 • C. He et al [18] found high-Cr-content ferrite stainless steel suffers from embrittlement when subjected to temperatures up to around 475 • C, due to the separation of the α (Fe-rich) ferrite and the α (Cr-rich) ferrite and the transformation of the Fe-rich α phase and the Cr-rich α phase to the α-(Fe,Cr) ferrite phase by using differential scanning calorimetry (DSC). Hechu et al [20] found the solid-state transformation of a δ dendrite core to a single γ phase without a peritectic reaction at 1358 • C. Some researches [15,21,22] show that the increase of Al content leads to a worse hot ductility and high Al content in steel can easily lead to deterioration of surface quality of continuous casting slabs [23]. However, Su et al [12] found that the increase of Al content in TRIP steel (0.03-0.87% Al) led to an overall increase of a reduction of area (RA) and better hot ductility.…”

Section: Introductionmentioning

confidence: 99%

High-Temperature Mechanical Properties of 4.5%Al δ-TRIP Steel

2019

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The high-temperature mechanical properties of a 4.5% Al-containing δ-transformation-induced plasticity (TRIP) steel were studied by using the Gleeble 3500 thermomechanical simulator. The zero ductility temperature (ZDT) and the zero strength temperature (ZST) were measured, and the brittle zones were divided. The phase transformation zone was determined by differential scanning calorimetry (DSC). The temperature of the phase transformation and the proportion of the phase were calculated by the Thermo-Calc software. The ZDT and the ZST of the 4.5% Al-containing δ-TRIP steel are 1355 and 1405 °C, respectively. The first brittle zone and the third brittle zone of the steel are 1300–1350 °C and 800–975 °C, respectively. The reason for the embrittlement of the third brittle zone of the 4.5% Al-containing δ-TRIP steel is that the α-ferrite formed at the austenite grain boundary causes the sample to crack along the grain boundary under stress. The ductility of the 4.5% Al-containing δ-TRIP steel decreases first and then increases with the increase of the α-ferrite. When the proportion of the α-ferrite reaches 37%, the reduction of area (RA) of the 4.5% Al-containing δ-TRIP steel is reduced to 44%. The 4.5% Al-containing δ-TRIP steel has good resistance to the high-temperature cracking.

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A novel approach for interpreting the solidification behaviour of peritectic steels by combining CSLM and DSC

Cited by 33 publications

References 27 publications

Characterisation of the Solidification of a Molten Steel Surface Using Infrared Thermography

Characterisation of the Solidification of a Molten Steel Surface Using Infrared Thermography

The Relationship between Nil-Strength Temperature, Zero Strength Temperature and Solidus Temperature of Carbon Steels

High-Temperature Mechanical Properties of 4.5%Al δ-TRIP Steel

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