Advanced Real Time Imaging: Iron & Steelmaking
Sponsored by: TMS Functional Materials Division, TMS Structural Materials Division, TMS: Advanced Characterization, Testing, and Simulation Committee, TMS: Alloy Phases Committee, TMS: Biomaterials Committee
Program Organizers: Jinichiro Nakano, MatterGreen; David Alman, National Energy Technology Laboratory; Il Sohn, Yonsei University; Hiroyuki Shibata, Tohoku University; Antoine Allanore, Massachusetts Institute of Technology; Noritaka Saito, Kyushu University; Anna Nakano, US Department of Energy National Energy Technology Laboratory; Zuotai Zhang, Southern University of Science and Technology; Candan Tamerler, University of Kansas; Bryan Webler, Carnegie Mellon University; Wangzhong Mu, KTH Royal Institute of Technology; David Veysset, Stanford University
Monday 2:00 PM
March 15, 2021
Room: RM 14
Location: TMS2021 Virtual
Session Chair: Il Sohn, Yonsei University; Jinichiro Nakano, USDOE National Energy Technology Laboratory
2:00 PM
In-situ Real Time Observation of Austenite Formation in Duplex Stainless Steels during Different Cooling Conditions: Wangzhong Mu1; Oscar Rova1; Sohei Sukenaga2; Hiroyuki Shibata2; 1Kth Royal Institute of Technology; 2IMRAM, Tohoku University
Austenite formation during cooling is an important issue for the microstructure control of duplex stainless steels (DSSs). The balance of austenite and ferrite fraction controls this material mechanical and corrosive resistance properties. In this work, the austenite formation from a comprehensive grade DSSs (2101, 2205, 2304, 2507 and 3207) has been observed in-situ by confocal laser scanning microscope (CLSM). Different cooling conditions were investigated on the austenite starting temperature and its fraction. The fraction is furthermore characterized by electron backscatter diffraction to identify the CLSM analysis results. The features of austenite nucleation and growth intergranular as well as intragranular are categorized to discuss, and the finding is supported by the theoretical calculation using classical nucleation theory. The final microstructure is compared with the real DSS as-cast and weldment specimens, in order to apply the obtained understanding to different engineering applications like casting, welding and potentially additive manufacturing.
2:20 PM
Dissolution Mechanism of Oxide Particles in Silicate Melt: A Theoretical Study Supported by In-situ Observation Experiment: Changji Xuan1; Wangzhong Mu2; 1Sandvik Machining Solutions AB; 2Kth Royal Institute of Technology
Oxide particle dissolution in the silicate melt is of vital importance for steel manufacturing. Initially, the oxide dissolution is investigated by the rotating dip test. With the development of confocal laser scanning microscope, new insights have been obtained due to in-situ image observation characteristics and precise process control. Comprehensive studies have been adapted to investigated effects of oxide type, slag composition, temperature, etc. on the dissolution kinetics. On the other hand, the theoretical study has also been developed by the supply of more reliable experimental data. Shrinking core (SRC) model is one of the classical method, which is usually proposed through a proper fitting with the experimental data. The different shape dissolution profiles indicate different mechanisms. This work develops a new SRC model which combines different mechanisms in one equation. Furthermore, machine learning method is integrated with the new physical model for a comprehensive study in this field.
2:40 PM
Direct Observation of Boron Nitride Dissolution in a Heat Resistant Martensitic Steel Using Confocal Scanning Laser Microscopy: Andrew (Drew) Huck1; Bryan Webler1; 1Carnegie Mellon University
Boron and nitrogen have become increasingly important in modern steels to impart greater creep resistance in forged products for elevated temperature applications. During solid-state processing, these two elements can combine under certain conditions and form coarse boron nitrides (BN), which can negatively impact properties and decrease the effect of these elements on creep resistance. Dissolution of these features in a heat-resistant martensitic steel has been observed in controlled furnace heat treatments. This study attempts to observe real time dissolution of BN particles using confocal scanning laser microscopy (CSLM) to confirm the thermodynamic stability range of these particles, which has been modeled using ThermoCalc. CSLM is a technique that allows surface observation with controlled temperature and atmospheric conditions, which should allow direct optical observation of these features. This should inform future heat treatment practices and expand knowledge of the thermodynamics of these particles.
3:00 PM Invited
Observation of Surface and Interfacial Phenomena at High Temperature: Masashi Nakamoto1; 1Osaka University
A wide variety of surface and interfacial phenomena occur in metallurgical high temperature processes. Therefore, the understanding of these phenomena is one of the one of the crucial issues in order to improve the efficiency of process and the quality of production.The researches on the observation of surface and interfacial phenomena have been recently focused on intensively in our research group. The foaming behavior of molten oxide and the direct bonding behavior between oxide and metal have successfully been observed by the utilization of a high-speed camera with illumination laser and a confocal laser scanning microscope etc.
3:20 PM
Wetting and Spreading Kinetics between Liquid CaO-SiO2 Slags and a Solid SiO2: Chaeyeon Yoo1; Jaewoo Myung1; Yongsug Chung1; 1Korea Polytechnic University
The objective of this study was to investigate wetting and spreading phenomena based on solubility difference of two compositions. Slags were prepared at 1873K (1600℃) by changing SiO2 content: 1) saturated composition; and 2) non-saturated composition. The substrate was β–quartz single crystal. Wetting and spreading experiments were carried out at 1873K (1600℃) in Ar (99.999%) atmosphere using Dispensed Drop Technique (DDT) with a high-speed camera (1000 frames/sec). Results showed that the apparent contact angle of non-saturated slag was smaller than that of saturated slag ( θF^NS=8°,θF^S=35°). The spreading rate of non-saturated slag was faster than that of saturated slag. Spreading is controlled by a viscous force. Both slags can fit the non-reactive model. However, for the non-saturated slag, the actual contact angle at the triple line was different from the apparent contact angle values. Dissolution might have contributed to such difference.
3:40 PM
In-situ Quantitative Study of Heat Transfer Performance of Mold Flux by Using Double Hot Thermocouple Technology: Zhe Wang1; Guanghua Wen1; Wenbo Jiang1; Ping Tang1; Shuheng Huang1; 1Chongqing University
The heat transfer ability of the mold flux is crucial for balancing the heat flux between the slab and mold. The double hot thermocouple technology (DHTT) is widely used for the qualitative determination of the heat transfer performance of the mold flux due to its advantages of rapid in-situ testing. However, the traditional DHTT cannot determine heat flux quantitatively, which limits the development of DHTT in the field of heat transfer measurement. In the current study, the in-situ quantitative investigation method based on DHTT was, for the first time, proposed to determine the heat transfer performance of mold flux. Herein, the heat flux of three mold fluxes with different Al2O3/SiO2 (A/S) ratios was estimated by using the new DHTT. The result showed that the heat flux decreases with increasing A/S ratio, which is consistent with the result of the parallel-sided plate method.
4:00 PM
In-situ Observation of Interfacial Phenomena between Magnetite and Matte at High Temperature by a Novel Optical Microscopic Technique: Seung-Hwan Shin1; Sakiko Kawanishi1; Sohei Sukenaga1; Junichi Takahashi2; Hiroyuki Shibata1; 1Tohoku University; 2Sumitomo Metal Mining
Generally, stagnation of magnetite at the slag/matte interface can occur in the copper smelting process using a flash furnace. The magnetite inhibits the absorption of the suspended matte in the slag phase into the matte phase, which leads to the copper loss. Therefore, the fast reaction rate between magnetite and matte can greatly contribute to reducing copper loss. In this study, we aim to clarify the reaction behavior by in-situ observation of the high-temperature reaction interface through the magnetite thin film, by focusing on the slight transparency for the visible light of the magnetite. The generated SO2 gas bubbles were observed at the interface, and the gases continued to stagnate even though they were agglomerated. From the beginning of the reaction, it is suggested that the formed gas at the interface can play a significant role to control the reaction rate between magnetite and matte.