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Knowledge of the viscoelastic properties of suspensions is essential for many industrial processes. Although oscillation and creep testing are widely used to measure the viscoelastic properties of complex fluids, few studies on the correlation between the viscoelastic properties measured using these methods have been published. This study aims to provide insights into the differences between these methods and determine which method is better suited for a particular application. The room-temperature viscoelastic properties of a suspension composed of polyethylene beads dispersed in a silicone oil matrix were measured by oscillation and creep testing and compared. The results of oscillation testing indicated that the suspension showed weakly elastic deformation, whereas the results of creep testing revealed that the suspension was relatively elastic, with the liquid phase showing lower viscosity. In addition, the viscosity measured by oscillation testing was lower than that measured by creep testing. When the imposed flow causes microstructural changes, such as when the shear flow and particle‒particle contact induce aggregation, the analyzed flow property considerably differs between testing methods.

A brace-type seismic damper made of an Fe-15Mn-11Cr-7.5Ni-4Si alloy solidified in the ferrite-austenite (FA) mode and SN490B steel, which can be constructed via welding, was proposed. To realize the proposed seismic damper, gas metal arc welding was applied to produce similar FMS/FMS fillet welds and dissimilar FMS/SN490B fillet weld joints. Based on the Schaeffler diagram, similar and dissimilar welding consumables were designed such that the fillet weld metal solidified in the FA mode without solidification cracking. Sound similar fillet welded joints were obtained using two types of welding consumables with different Cr/Ni equivalent ratios although both the similar fillet weld metals had a coarse columnar austenite grain structure. These displayed higher tensile strengths (716–736 MPa) and marginally lower elongations (67–70%) than the FMS alloy. Moreover, a similar fillet weld metal with a chemical composition almost identical to that of the FMS alloy exhibited a remarkable low-cycle fatigue life (5740 cycles). This was shorter than that of the FMS alloy (9351 cycles) owing to the easier formation of α'-martensite. A dissimilar fillet welded joint with a chemical composition within the austenite region was produced without solidification cracking. The dissimilar fillet weld metal showed high tensile strength (867 MPa) and total elongation (61%). These were comparable to those of similar fillet weld metals.

Recently, remarkable advances have been made in statistical analyses based on deep-learning techniques. Applied studies of deep learning have been reported in various industrial fields, including the iron and steel-making industries. The production of iron and steel requires a variety of processes, such as the processing of ingredients, iron-making, casting, and rolling. Consequently, the data acquired from them are diverse, and various tasks exist that can be assisted by deep-learning algorithms. Hence, providing a summary of the application is helpful for researchers specializing in information science to grasp the current trend of applied studies on deep learning techniques and for researchers specializing in each field of the iron and steel-making industry to understand what types of deep learning techniques are being utilized in other specialized fields. Therefore, in this study, we summarize the current studies on the application of deep learning in the iron- and steel-making fields by organizing them into several categories of processes and analytical methodologies. Furthermore, based on the results, we discuss future perspectives on the development of deep-learning techniques in this field.

The microstructure of the B1-type TiC formed during solidification and its mechanical properties were investigated using arc-melted Fe–Ti–C ternary alloys. The TiC formed at relatively high temperatures in the liquid as the primary phase exhibited a dendritic shape. With decreasing temperature and/or decreasing Ti and C content in the liquid, the morphology of the TiC changed to a cubic shape with a {001}_TiC habit plane, a plate shape with a {011}_TiC habit plane, and a needle shape with a preferential growth direction of <001>_TiC. The morphology of the TiC was characterized by the anisotropy of its surface energy and its growth rate. The cubic shape with a {001}_TiC habit plane was formed as a result of the {001}_TiC surface exhibiting the lowest surface energy among the TiC surfaces. However, the plate shape with a {011}_TiC habit plane and the needle shape with a <001>_TiC preferential growth direction likely formed because the slowest and fastest growth rates corresponded to the <011>_TiC and <001>_TiC directions, respectively. At room temperature, the alloy with dendritic TiC was fractured in the elastic deformation region because TiC exhibited no plastic deformation. However, the results obtained at 800°C suggested that the TiC exhibited plastic deformability and that the alloy with the dendritic TiC was also plastically deformed.

In the continuous casting process, the temperature of liquid steel in tundish determines the casting speed and secondary cooling conditions, and then influences the billet quality. It's very important to measure the temperature of liquid steel in tundish quickly and accurately. However, the initial response lag of blackbody cavity sensor is inevitable since the time is required for the sensor inner wall and the liquid steel reaching thermal equilibrium by heat transfer. In this paper, in order to eliminate the initial response lag of sensor, a heat transfer model of sensor is established. The heat transfer characteristics and cavity integral emissivity of sensor with different depths immersed into liquid steel are analyzed. The analytical solution of sensor temperature is derived by separation of variables method and superposition principle, and is verified by the actual temperature measurement data. Then an innovative method of liquid steel temperature rapid identification is deduced and validated by the actual measurement data. The results show that the initial response lag of sensor is greatly shortened and the temperature measurement efficiency is improved. This study provides a theoretical method for improving the initial response speed of sensor.

The interfacial tension between the liquid steel and molten slag is one of the key properties to control the entrapment of mold flux in molten steel in the continuous casting process. A dynamic change of the interfacial tension is observed when deoxidized iron and silicate slag are in contact, which can be explained by the oxygen absorption and desorption at the iron/slag interface. However, the dynamic change of the interfacial tension is influenced by other surfactant components of the molten iron and slag. Fluoride ions are fundamental component of mold flux, and recognized as the surface active component of molten slag. The effect of fluoride ions in slag on the interfacial tension has not been critically evaluated. Here, the effect of fluoride ions in slag on the interfacial tension between molten iron and molten silicate slag was evaluated at 1823 K, where the fluoride-containing slag compositions were designed to exhibit the same SiO₂ activity and slag viscosity as those of the fluoride-free slag. Compared with the case of molten iron and fluoride-free slag, the interfacial tension between the molten iron and fluoride-containing slag was initially lower. Except the effect of oxygen adsorption, fluoride ion was considered to directly decrease the interfacial tension. However, as the fluoride content in slag was higher, the interfacial tension tended to show the higher value at the final state. This behavior was attributed mainly to fluoride vaporization as SiF₄, which reduce the SiO₂ activity in slag and thus equivalent oxygen content at the iron/slag interface.

The increase of hydrogen usage in a blast furnace is expected to affect the reduction degradation of ferrous burden materials and influence the gas permeability inside the furnace. Previous studies show a disagreement on the effect of H₂ on reduction degradation, with the extent of degradation depending on the H₂ content and type of ferrous burden materials. In this study, the reduction degradation of sinter, lump, and pellet was compared using the reduction degradation test under different gas mixtures containing CO and H₂, covering the gas composition of conventional and H₂ injection blast furnaces. Lump (Newman Blend Lump NBLL) and pellets show a lower RDI_-2.8 than sinter under all the gas compositions tested. Higher RDI_-2.8 values were obtained for all burden materials with a reducing gas containing both CO and H₂ compared to CO or H₂ only. The addition of H₂ to CO increases the pore diffusion rate allowing reducing gas to reach the centre part of the particles, leading to the reduction of hematite to magnetite and subsequent crack formation across the whole particles. Compared to the conventional blast furnace case, NBLL lump and sinter show a lower degradation for the H₂ injection case while it was the opposite for the pellet, suggesting the necessity of reviewing overall burden materials to optimise the hydrogen injection in the blast furnace.

The hardness of martensitic steels with high M_s temperatures is reduced by auto-tempering after transformation, therefore the true hardness of martensite with carbon in fully solid solution is not known. In this study, we investigated a method to quantitatively evaluate the true hardness of quenched martensite unaffected by auto-tempering and the effect of auto-tempering was quantitatively evaluated by the diffusion area of carbon in bcc iron at temperatures below 400°C. As a result, it was clarified that the effect of auto-tempering is more pronounced in steels with an M₅₀ temperature higher than 300°C and that the softening behavior of martensitic steels can be uniformly evaluated regardless of the carbon content if the activation energy of carbon diffusion is known. Furthermore, it was clarified that the degree of auto-tempering can be quantitatively evaluated by calculating the integral diffusion area S (= ∑Dt) below the M₅₀ temperature during quenching.

Automotive suspension springs are required to be high-strength and lightweight, and currently have a maximum strength of 2000 MPa. In addition, they must have high resistance to hydrogen embrittlement in the service environment. From previous research, Si addition or rapid tempering improves the hydrogen embrittlement resistance of low alloy steel. In this study, we investigated the hydrogen embrittlement properties of steel samples with different Si contents and tempering rates and the effects of the fine iron carbides and retained austenite on its properties for 2000 MPa suspension spring steel. JISSUP7 (2.0Si) and SAE9254 (1.4Si) spring steels were tempered at different tempering rates by induction (IH) and furnace heating (FH) methods. Four-point bending tests under corrosion cycles were performed on these steels, and the time to failure was measured. The results show that the 2.0Si-IH steel with higher Si content and higher tempering rate has the longest fracture life and highest resistance to hydrogen embrittlement, even with relatively high diffusible hydrogen content. The size and volume fraction of iron carbides and retained austenite were evaluated by TEM, EBSD, and synchrotron XRD, and the 2.0Si-IH steels were found to have the smallest size and the highest volume fraction of fine iron carbides Fe_2-3C(ε) and the highest amount of retained austenite. It is considered that the fine iron carbides of Fe_2-3C(ε) work as hydrogen trap sites and that their high dispersion suppresses dislocation movement. They suppress hydrogen accumulation in stress concentrated areas and are expected to improve resistance to hydrogen embrittlement.

This study focuses on the fracture mode of 201 austenitic steel at room temperature (RT) and at -40 °C for one hour and three hours. The results reveal that at room temperature, the fracture is dominated by ductile behavior. At - 40 °C, the fracture mode is a mix of ductile and brittle behavior. Type 201 austenitic stainless steel has a low stacking fault energy value (about 16 mJ.m^-2 at RT), leading to the activation of the transformation-induced plasticity (TRIP) effect. When the sample is soaked at -40 °C for three hours, deformation-induced martensite transition (DIMT) formation with the volume fraction rises significantly to 19.9 %. At -40 °C for 3 hours, the alloy's impact energy absorption is reduced by 39%. The interaction of deformed austenite grains with previous austenite grain boundaries results in the formation of serrated grain boundaries in samples soaked at -40 °C. Serrated grain boundaries prevent crack propagation and reduce crack expansion at the grain boundary during the fracture of this alloy. The width of the crack at serrated grain boundaries is 38% less than that of the straight grain boundary.