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, Sourthern 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; Pranjal Nautiyal , University of Pennsylvania
Thursday 8:30 AM
March 23, 2023
Room: Aqua 310A
Location: Hilton
Session Chair: Noritaka Saito, Kyushu University
8:30 AM Invited
In-situ Visualization of Retrograde Melting Phenomenon During Solidification of Boron-bearing Steels: Hongbin Yin1; 1ArcelorMittal Global R&D
It is well known that the addition of boron to steels can cause difficulties during continuous casting, including surface cracks and internal cracks of the cast products. In severe cases, breakout and slab breakage can occur. Studies on the effect of boron on Fe-B alloys pseudo-binary phase diagrams at various carbon levels found that small addition of boron introduces the possibility of so-called retrograde melting, i.e., upon cooling, the steel initially completely solidifies and then remelts at segregated interdendritic regions and grain boundaries at temperatures approaching 1200 oC. This phenomenon is the primary cause of casting difficulties of B-bearing products. To confirm the theoretical work on the finding of retrograde melting phenomenon, Confocal Scanning Laser Microscope studies were carried out for “in-situ” observation. These studies revealed the existence of the retrograde melting phenomenon in commercial B-bearing steels at temperatures below 1200 oC. The present paper summarizes the results.
8:50 AM Cancelled
Combination of Confocal Laser Scanning Microscopy and Machine Learning Model for the Prediction of Oxide Dissolution in the Steelmaking Slag: Chunguang Shen1; Changji Xuan2; Wangzhong Mu1; 1KTH Royal Institute of Technology; 2Sandvik Manufacturing Solutions AB
Dissolution of non-metallic inclusion in the steelmaking slag is important for cleanliness control of steel product. With the development of high-temperature confocal laser scanning microscope (HT-CLSM), new insights have been obtained due to its in-situ image observation characteristics, higher resolution and precise process control. However, HT-CLSM for this measurement has limitations, e.g., selecting slag composition, including transition metal oxide. In addition, it is time-consuming and challenging to succeed for every measurement. Machine learning (ML) is the key enabling technology for material science and industry digitalization. The database for ML model is collected using almost all available HT-CLSM experimental data, and subsequently established database can be trained by the ensemble learning method. Al2O3 dissolution is the primary process to be predicted in the current study, but all the other kinds of oxide dissolution, e.g., MgO, SiO2 and MgAl2O4, are included and tested in the model.
9:10 AM Cancelled
Does Confocal Laser Scanning Microscopy Have the Suitable Capability to Use in Physical Metallurgy?: Wangzhong Mu1; 1KTH Royal Institute of Technology
High-temperature confocal laser scanning microscopy (HT-CLSM) is an in-situ direct observation device of crystallization behaviors in metals, and silicates (slag, flux, etc.) This facility utilizes a halogen heating lamp focused onto the surface of the specimen in a small crucible. This facility was born 30 years ago, and it is suited for in-situ studies of solidification, inclusion behavior in the liquid steel, slag crystallization, etc. A few examples performed in KTH will be summarized. Furthermore, the capability of HT-CLSM used in physical metallurgy, in particular, microstructure evolution in sold state steels will be discussed. A few examples of low-alloy and stainless steel are given. The pros and cons of HT-CLSM applied in physical metallurgy are summarized. Last but not least, the combinational approach using HT-CLSM supplemented with other methodologies, e.g. large-scale facility is briefly discussed. This work aims to extend the application of this in-situ observation methodology in comprehensive metallurgy.
9:30 AM Cancelled
Microstructure Evolution of TRIP-assisted Lean Duplex Stainless Steel UNS S32101 during In-situ Tensile: Jingyuan Li1; Xinghai Zhang1; Wangzhong Mu2; 1University of Science and Technology Beijing; 2KTH Royal Institute of Technology
In-situ EBSD technique is a new technique developed in recent years. It can be used to stretch small specimens in scanning electron microscopy and then photograph EBSD, so that the evolution of microstructure during deformation can be analyzed in situ. In our study, the microstructure transformation and plastic deformation behavior of lean duplex stainless steel UNS S32101 during tensile are investigated by in-situ EBSD technique. The results indicate that strain-induced martensite transformation occurs in the metastable austenite during the deformation, following two typical sequences of γ → α′ and γ→ ε → α′. Furthermore, the nucleation site and strain-induced transformation process of martensite can be observed by in-situ EBSD technique. The α′-martensite nucleates preferentially at the large angle grain boundaries between austenite grains as well as the intersection of annealing twin boundaries and grain boundaries, growing rapidly along annealing TBs, GBs and slip bands.
9:50 AM Break
10:10 AM
Visualization of Molten Slag Suspension by Electrical Impedance Tomography: Hayato Segawa1; Miku Arisato2; Kento Nakanishi2; Prima Sejati1; Yosephus Prayitno1; Kunihiko Nakashima2; Noritaka Saito2; Masahiro Takei1; 1Chiba University; 2Kyushu University
In actual high-temperature metallurgical processes, molten slag is not a homogeneous melt, but a multiphase melt containing secondary phases such as solids and gases. The presence of these second layers is known to have a significant effect on the control factors of high-temperature metallurgical processes, such as viscosity and thermal conductivity. In this presentation, we apply the electrical impedance tomography method, which is a technique to measure electrical quantities such as capacitance and impedance at ultra-high speed in multiple dimensions and visualize the concentration distribution in a multiphase flow field in four dimensions (three-dimensional space + time) using an image reconstruction algorithm, to a suspension melted at a high temperature.
10:30 AM
High-Temperature Wetting of Calcium Alloys and Molten Salts: Athan Sanders1; Bitong Wang1; Douglas Kelley1; 1University of Rochester
Wetting of steels by calcium alloys and molten salts is of interest to optimizing the efficiency of liquid metal batteries. Low contact angle is indicative of good wetting, which in turn is indicative of good electrical contact and low resistance. In this study, we utilize the sessile drop method to observe contact angles of calcium alloys and molten salts on steel substrates at 500℃, the operating temperature of the batteries. Solid reagents are mixed inside a needle heating device, and a drop is deposited onto the substrate below that sits on a thermal plate. Afterwards, a thermal cycling experiment is performed where the temperature of the plate is repeatedly lowered until the drop solidifies and increased until it melts. Video of the drop is recorded, and then analyzed by the open-source program OpenDrop. With the contact angles measured, the relative wetting of each fluid and substrate combination can be determined.