| 1. |
- Bölke, Kristofer, et al.
(författare)
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Experimental Determinations of Mixing Times in the IronArc Pilot Plant Process
- 2019
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Ingår i: Metals. - : MDPI. - 2075-4701. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- IronArc is a newly developed technology and an emerging future process for pig iron production. The long-term goal with this technology is to reduce the CO2 emissions and energy consumption compared to existing technologies. The production rate of this process is dependent on the stirring, which was investigated in the pilot plant process by measuring the mixing time in the slag bath. Moreover, slag investigations were done both based on light optical microscope studies as well as by Thermo-Calc calculations in order to determine the phases of the slag during operation. This was done because the viscosity (which is another important parameter) is dependent on the liquid and solid fractions of the slag. The overall results show that it was possible to determine the mixing time by means of the addition of a tracer (MnO2 powder) to the slag. The mixing time for the trials showed that the slag was homogenized after seconds. For two of the trials, homogenization had already been reached in the second sample after tracer addition, which means <= 8 s. The phase analysis from the slag indicated that the slag is in a liquid state during the operation of the process.
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| 2. |
- Frisk, Robin, et al.
(författare)
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Cast Structure in Alloy A286, an Iron-Nickel Based Superalloy
- 2019
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Ingår i: Metals. - : MDPI. - 2075-4701. ; 9:6
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Tidskriftsartikel (refereegranskat)abstract
- The structure and segregation of a continuously cast iron-nickel based superalloy were investigated. Cross-sectional samples were prepared from the central section of a 150 x 150 mm square billet. The microporosity was measured from the surface to the center and theoretical conditions for pore formation were investigated. A central porosity, up to 10 mm in width, was present in the center of the billet. The measured secondary arm spacing was correlated with a calculated cooling rate and a mathematical model was obtained. Spinel particles were found in the structure, which acted as inoculation points for primary austenite and promoted the formation of the central equiaxed zone. Titanium segregated severely in the interdendritic areas and an increase of Ti most likely lead to a significant decrease in the hot ductility. Precipitates were detected in an area fraction of approximately 0.55% across the billet, which were identified as Ti(CN), TiN, eta -Ni3Ti, and a phosphide phase.
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| 3. |
- Pirouznia, Pouyan, et al.
(författare)
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An investigation of the temperature distribution of a thin steel strip during the quenching step of a hardening process
- 2019
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Ingår i: Metals. - : MDPI. - 2075-4701. ; 9:6, s. 1-14
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Tidskriftsartikel (refereegranskat)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 degrees 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 degrees C and 41 degrees 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.
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| 4. |
- Pirouznia, Pouyan, et al.
(författare)
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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
- 2019
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Ingår i: Metals. - : MDPI. - 2075-4701. ; 9:9
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Tidskriftsartikel (refereegranskat)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 Nm(3)/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.
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