8 results on '"Jönsson, Pär G."'
Search Results
2. The Impact of the Gas Inlet Position, Flow Rate, and Strip Velocity on the Temperature Distribution of a Stainless-Steel Strips during the Hardening Process
- Author
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Pirouznia, Pouyan, Andersson, Nils Å. I., Tilliander, Anders, and Jönsson, Pär G.
- Subjects
lcsh:TN1-997 ,Physics::Instrumentation and Detectors ,heat transfer ,continuous hardening process ,numerical modelling ,martempering ,computational fluid dynamics ,lcsh:Mining engineering. Metallurgy - Abstract
A non-uniform temperature across the width of martensitic stainless-steel strips is considered to be one of the main reasons why the strip exhibits un-flatness defects during the hardening process. Therefore, the effect of the gas inlet position in this process, on the temperature distribution of the steel strip was investigated numerically. Furthermore, an infrared thermal imaging camera was used to compare the model predictions and the actual process data. The results showed that the temperature difference across the width of the strip decreased by 9% and 14% relative to the calculated temperature and measured values, respectively, when the gas inlet position was changed. This temperature investigation was performed at a position about 63 mm from the bath interface. Moreover, a more symmetrical temperature distribution was observed across the width of the strip. In addition, this study showed that by increasing the amount of the hydrogen flow rate by 2 Nm3/h, a 20% reduction of temperature difference across the width of strip was predicted. Meanwhile, the results show that the effect of the strip velocity on the strip temperature is very small.
- Published
- 2019
3. Numerical analysis of the temperature distribution in a martensic stainless steel strip during hardening
- Author
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Pirouznia, Pouyan, Andersson, Nils Å.I., Tilliander, Anders, and Jönsson, Pär G.
- Subjects
Hardening process ,Numerical modelling ,Technology: 500 [VDP] ,Heat transfer ,Strip ,Process industries ,Martempering - Abstract
Due to the increasing demands on higher qualities of thin martensitic steel strips, a great attention needs to be paid to the dimension quality of the finished product within the hardening line. The temperature distribution within the strip during the process influences the flatness of the finished product. Therefore, a FEM model was developed based on physical theories. Specifically, the temperature for the section before martensitic transformation was predicted by using a steady state approach. In addition, the results of the numerical predictions were compared to measured temperature performed in industry by using infrared thermal imaging. The results showed that a significant temperature difference exists across the width of the strip. This difference was 41°C and 48°C at the position close to the bath interface according to the thermal imaging and modelling results, respectively. Furthermore, the temperature measurements showed that the temperature of the strip decreased by 245°C from the furnace temperature within the gas box beyond the hardening furnace. The measurements were performed at a position about 21mm away from the molten metal bath interface. Overall, the results of this study can be seen as initial fundamental knowledge of the modelling of the hardening process. Thereby, this knowledge can be used to modify the current hardening process as well as be used as input to study the stress in strip in future investigations.
- Published
- 2017
4. The Influence of Swirl Flow on the Flow Field, Temperature Field and Inclusion Behavior when Using a Half Type Electromagnetic Swirl Flow Generator in a Submerged Entry and Mold.
- Author
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Yang, Ying, Jönsson, Pär G., Ersson, Mikael, Su, Zhijian, He, Jicheng, and Nakajima, Keiji
- Subjects
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SWIRLING flow , *METAL inclusions , *HEAT transfer , *LIQUID metals , *METALLURGY - Abstract
In the preceding work, the inclusion behavior in a submerged entry nozzle (SEN) and mold induced by using a swirl flow has been investigated. The results showed that a swirl flow can effectively promote the inclusions removal to the meniscus as well as reduce the inclusions entrapment at the solidified shell wall. Moreover, that the swirl flow was generated by using a full type electromagnetic swirl flow generator (EMSFG). In the present work, a kind of a half type EMSFG was investigated, since it is easier to implement in a production scale. The influence of the stirrer on the fluid flow, heat transfer, and inclusion behavior in the SEN and mold was studied. Furthermore, a comparison between these two types of EMSFG from the aspects of flow field, temperature field, and inclusion behavior was done. In addition, the effect of different magnetomotive forces, inclusion sizes, densities as well as boundary conditions on the inclusion behavior was studied. The results show that the effect of a half type EMSFG (88000 AT) on the molten steel is very close to a full type case (44000 AT). More specifically, the flow pattern, temperature distribution as well as inclusion behavior in the SEN and mold look very similar. Also, it was found that from the viewpoints of the inclusions separation to the mold meniscus and the inclusions trapping at the solidified shell wall, better results could be obtained for a 'Trap' boundary condition when using half type EMSFGs. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
5. Inclusion Behavior under a Swirl Flow in a Submerged Entry Nozzle and Mold.
- Author
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Yang, Ying, Jönsson, Pär G., Ersson, Mikael, and Nakajima, Keiji
- Subjects
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ELECTROMAGNETIC fields , *NOZZLES , *HEAT transfer , *CONTINUOUS casting , *METAL castings , *STEEL - Abstract
Previous studies have verified that a swirl flow generated in a submerged entry nozzle (SEN) can effectively improve a flow pattern and a heat transfer in a continuous casting (CC) process. In order to obtain a further in-depth understanding with respect to the effect of a swirl flow on a CC process, the inclusion behavior in a SEN and a mold was studied in the present work. The flow field and the temperature field of molten steel as well as the inclusion behavior in a SEN and a square bloom mold were simulated under the influence of a rotating electromagnetic field (swirl generator). Also, the influence of different inclusion parameters such as the densities, sizes, and boundary conditions, on the inclusion behavior was studied. The results show that a flow pattern in a SEN can be characterized into three distinct flow regions: an accelerating flow of molten steel from an electromagnetic swirl flow generator (EMSFG) inlet to an EMSFG center, a decelerating flow of molten steel from an EMSFG center to an EMSFG outlet, and a recirculation flow of molten steel from an EMSFG outlet to an SEN outlet. In addition, it was found that light Al2O3 inclusion moves towards the rotational center by a centrifugal force, and that a swirl flow prevents nozzle clogging. Moreover, it was also found that the inclusion separation to a mold meniscus increased and that the inclusions trapped into a solidified shell wall decreased when using a swirl flow. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
6. Interpretation of Tap Induced Cyclic Temperatures in the Blast Furnace Lining.
- Author
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Swartling, Maria, Tilliander, Anders, Saxén, Henrik, and Jönsson, Pär G.
- Subjects
LININGS of blast furnaces ,HEARTHS ,THERMOCOUPLES ,APPROXIMATION theory ,FUNCTIONAL analysis ,HEAT transfer ,MATHEMATICAL models of thermodynamics ,ELECTRONIC data processing - Abstract
The thermal behavior of the blast furnace hearth was studied using modeling. The focus was the effect of the size and shape of the taphole clay layer around the taphole. Four different cases have been calculated: one reference case and three cases with different taphole clay layer geometries. It was found that the calculated peak-to-peak amplitudes of the lining temperatures during the tap cycles at the location of a thermocouple can be approximated as a linear function of the taphole clay layer thicknesses for all calculated cases. Modeling was also done where both the 90th and the 10th percentile of the observed peak-to-peak values of the studied tap cycles were included to describe the behavior of the operating furnace. The taphole region can be divided into three categories based on how well the model can describe the measured process data: below, at, and above taphole level. Below the taphole level, the measured lining temperature variations are smaller than for the calculated results. At the taphole level, the model can describe the behavior well. Above the taphole level the measured lining temperature variations are larger than for the calculated results. It was concluded that in order to make a more accurate heat transfer model of the taphole region, the presence of a skull build-up below the taphole, erosion above the taphole, and the bath level variations need to be taken into account. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
7. Effect of Thermal Buoyancy on Fluid Flow and Residence-Time Distribution in a Single-Strand Tundish.
- Author
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Sheng, Dong-Yuan and Jönsson, Pär G.
- Subjects
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FLUID flow , *BUOYANCY , *COMPUTATIONAL fluid dynamics , *HEAT losses , *TEMPERATURE distribution , *NATURAL heat convection , *VORTEX generators - Abstract
Natural convection of molten steel flow in a tundish occurs due to the temperature variation of the inlet stream and heat losses through top surface and refractory walls. A computational fluid dynamics (CFD) model was applied to study the effect of thermal buoyancy on fluid flow and residence-time distribution in a single-strand tundish. The CFD model was first validated with the experimental data from a non-isothermal water model and then applied to both scale-down model and prototype. The effects of flow control devices, including weir, dam and turbulence inhibitor, were compared and analyzed. Parameter studies of different heat losses through the top surface were performed. The results show that thermal buoyancy has a significant impact on the flow pattern and temperature distributions of molten steel in the tundish. The increase of heat loss through the top surface shortens the mean residence time of molten steel in the tundish, leading to an increase in dead volume fraction and a decrease in plug flow volume fraction. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
8. An investigation of the Temperature Distribution of a Thin Steel Strip during the Quenching Step of a Hardening Process.
- Author
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Pirouznia, Pouyan, Andersson, Nils Å. I., Tilliander, Anders, and Jönsson, Pär G.
- Subjects
STEEL strip ,TEMPERATURE distribution ,THERMAL imaging cameras ,MARTENSITIC transformations ,INFRARED imaging - Abstract
The dimension quality of the strip within the hardening process is an essential parameter, which great attention needs to be paid. The flatness of the final product is influenced by the temperature distribution of the strip, specifically across the width direction. Therefore, based on physical theories, a numerical model was established. The temperature of the strip for the section before the martensitic transformation was objected in the predicted model by using a steady state approach. In addition an infrared thermal imaging camera was applied in the real process in order to validate the results and to improve the boundary conditions of the numerical model. The results revealed that the temperature of strip decreased up to 250 °C within the area between the furnace and the quenching bath. This, in turn, resulted in significant temperature difference across the width of the strip. This difference can be up to 69 °C and 41 °C according to the numerical results and thermal imaging data, respectively. Overall, this study gave a better insight into the cooling step in the hardening process. In addition, this investigation can be used to improve the hardening process as well as an input for future thermal stress investigations. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
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