Temperature and emissivity determination of liquid steel S235

Schöpp, Heinz; Sperl, A; Kozakov, Ruslan; Gött, Gregor; Uhrlandt, Dirk; Wilhelm, G

doi:10.1088/0022-3727/45/23/235203

Cited by 36 publications

(17 citation statements)

References 19 publications

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“…8, all emissivity curves with different film thickness show an initially rapid decrease with temperature and an approximately constant value for temperatures above ~ 70 °C. This trend is similar to the study of liquids presented by Schopp et al [37] and also agrees with the results reported in [49], in which the emissivity or absorptivity of hydrocarbons or other liquids increased with film thickness for values up to 4.5 μm.…”

Section: Resultssupporting

confidence: 93%

3D Measurements of Lubricant and Surface Temperatures Within an Elastohydrodynamic Contact

Reddyhoff

Dini

2017

Tribol Lett

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We present an infrared microscopy technique, capable of measuring the temperature of both the bounding surfaces and the oil film in an elastohydrodynamic contact. This technique can, for the first time, spatially resolve the oil film temperature in three dimensions. The contact is produced by loading a steel ball against a sapphire disc, and the film is viewed using an infrared microscope focussing through the disc. Two band pass filters are used to isolate the radiation from the oil film, and Planck's law is applied to data obtained at a known temperature as part of the calibration procedure. The proposed technique requires the emissivity of the oil film to be measured, which is acquired in situ and is shown to vary strongly as a function of thickness and temperature. The technique is validated under pure rolling conditions, when the temperature of the oil film is equal to the controlled lubricant reservoir temperature, and also compared to an equation commonly used to predict average film temperatures, confirming the value of the unknown constant. The technique is then used to gain insights into the thermal/rheological behaviour within a contact. This is important since the temperature of elastohydrodynamic contacts is critical in determining friction and hence the efficiency of machine components and this technique enables much needed validation and provides input data for CFD and numerical simulations.

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Section: Resultssupporting

confidence: 93%

3D Measurements of Lubricant and Surface Temperatures Within an Elastohydrodynamic Contact

Reddyhoff

Dini

2017

Tribol Lett

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“…For a smooth iron or steel surface, the average normal emissivity in the bolometer's spectral range is 0.2 at room temperature and gradually increases with temperature up to 0.95 due to the growth of an oxide layer. 8,14,[24][25][26][27] A steep drop in the emissivity after the solidliquid phase transition 14,22 of the material therefore corresponds to a decrease of the measured bolometer temperature T BM . This allows the extraction of the melt time t M , the time at which the melt front reaches the back side of the plate.…”

Section: Resultsmentioning

confidence: 99%

“…14,22 Since conduction is the dominant heat transfer mechanism at least up to the melting point, this choice does not affect the initial heating process, 11,15 but after that, resulting temperatures serve as lower boundaries. Figure 3 shows a simulated temporal temperature evolution at the back side of a 1 mm thick iron plate.…”

Section: Optical Propertiesmentioning

confidence: 99%

Numerical modeling and characterization of the laser–matter interaction during high-power continuous wave laser perforation of thin metal plates

Horak

Heunoske

Lueck

et al. 2015

Journal of Laser Applications

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The phenomena occurring during laser-metal interaction depend on a variety of parameters such as laser wavelength, intensity, and thermophysical and optical properties of the irradiated material. This work comprises a detailed study of the perforation process of thin iron and steel plates under CW laser radiation at a wavelength of 1.07 lm. Experiments were carried out over a wide range of intensities between 0.1 and 100 kW/cm 2 , and with beam radii in the millimeter and centimeter range. Additionally, we describe a method applying contact-free radiative temperature measurements, which allows the measurement of melt-through times without an exact knowledge of the plate's spectral surface emissivity. A detailed numerical model is presented and employed to analyze, interpret, and predict data gathered from the experiments. The model is shown to produce accurate predictions and is in good agreement with experimental data. Furthermore, our results indicate that in the investigated regime perforation is governed by gravitational and surface forces. Based on this hypothesis, a criterion for the onset of the perforation explaining the observed local minimum in the perforation time versus beam radius curve is presented. V C 2015 Laser Institute of America. [http://dx

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“…As emissivity is a constant problem in radiometric temperature measurements, Schöpp et al [4] and Muller et al [5] combined near infra-red high speed camera with a spectrometer. Spectrometer is used to perform a point-wise spectrum.…”

Section: Introductionmentioning

confidence: 99%

Liquid metals surface temperature fields measurements with a two-colour pyrometer

et al. 2017

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Temperature and emissivity determination of liquid steel S235

Cited by 36 publications

References 19 publications

3D Measurements of Lubricant and Surface Temperatures Within an Elastohydrodynamic Contact

3D Measurements of Lubricant and Surface Temperatures Within an Elastohydrodynamic Contact

Numerical modeling and characterization of the laser–matter interaction during high-power continuous wave laser perforation of thin metal plates

Liquid metals surface temperature fields measurements with a two-colour pyrometer

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