Increasing the utilization of steel scrap is strongly required for reducing CO₂ emission in iron- and steel-making processes. In steel scrap recycling, the content of tramp elements in steel (such as copper and tin) inevitably increases. Accordingly, it is important to understand the thermodynamic characteristics of relevance to the accumulation of tramp elements in molten steel. The values of the interaction coefficients of Mo, B, Ni, Ti, and Nb with Sn in molten iron were reported previously. However, little is known about the interaction coefficients of alloying elements with tramp elements in molten high-chromium steel. In this work, the interaction coefficients of Mo, B, Ni, Ti, and Nb with Sn in the molten Fe–18mass%Cr alloy were measured at 1873 K by a chemical equilibration technique that uses the liquid immiscibility of the Fe–18mass%Cr alloy and Ag, yielding the following results:

The results show that the values of the interaction coefficients of M with Sn in the Fe–18mass%Cr alloy are smaller than those for molten iron, which were measured in the previous work, except for titanium. The interaction coefficients of M with Sn in Fe and Fe–18mass%Cr alloy were estimated based on a regular solution model. The estimated interaction coefficients of B, Ni, and Ti with Sn in molten iron and Ni and Ti with Sn in the molten Fe–18mass%Cr alloy reasonably agree with the measured values.

Effect of copper on solidification microstructure and solidification process were investigated for high carbon high speed steel type alloys (Fe-2.0%C-5%Cr-5%Mo-5%V-0~7.5%Cu in mass%). The microstructure of all as-cast specimens with different copper content is dendrite consisting mainly of primary γ, MC-γ eutectic and M₂C-γ eutectic. In the copper-free specimen, the shape of dendrite is granular (or equiaxed), while in the copper added specimens, it is columnar, and the columnarization trend become more pronounced with increasing the amount of copper content. Furthermore, the secondary dendrite arm spacing decreased with increasing amount of copper content. The volume fraction of primary γ dendrite gradually decrease and MC-γ eutectic gradually increase with increasing of the amount of copper content. While the volume fraction of M₂C-γ eutectic is approximately constant regardless of the amount of copper content. The concentrations of chromium, molybdenum and vanadium within microstructure were approximately constant regardless of the amount of copper content in any microstructures. While the concentration of copper within microstructure was higher in order of dendrite, MC-γ eutectic and M₂C-γ eutectic compared with any copper content, and its order corresponds to the solidification prosses. These results suggest that copper tends to remain in the solid phase (that is dendrite) rather than redistribute to the liquid phase during solidification.

For manufacturers, rapid and accurate quality control of materials and products in the field is essential for improving competitiveness. Rebound hardness testing is one of the fundamental material tests expected to meet this requirement. However, it has been known that many factors affect rebound hardness which may cause the fluctuation in the measured value. In order to elucidate the effect of the fixing method of the specimen, the coefficient of restitution of a hammer using a Vickers indenter was compared with and without bolting the specimen to the base. The motions of the hammer and the specimen were measured simultaneously using two laser Doppler vibrometers and were also numerically analyzed using an elastoplastic finite element method. It has been clarified that, in the case of without bolting, the restitution coefficient is decreased compared to with bolting. The decreasing tendency becomes larger as the impact point moves away from the specimen center. The rebounding behaviors of the hammer and the specimen without bolting can be reproduced with a numerical model in which an appropriate elastic film is inserted between the specimen and the base. The numerical results show that the hammer impact causes rigid body motion in the specimen, which consumes hammer energy, resulting in a decrease in the coefficient of restitution. The range in which the coefficient of restitution can change is also evaluated by assuming a simple two-body collision model.

In the measurement of iron and steel processes, the measurement of temperature concentration distribution is very important for the analysis and control of in-furnace phenomena in order to obtain in-furnace information. However, thermocouples and gas sampling methods are used, but since they are contact and point measurements, they disturb the measurement field, require modification of equipment and piping, have low time response (10 Hz), and are affected in accuracy (20% or more) by environmental fluctuations. This report describes the development of a technology for simultaneous measurement of multiple components such as O₂, CO, and CO₂ concentrations in a furnace, acquisition of a spectral database necessary for measurement using various calibrators, adjustment of the optical axis when installing a sensor with a large laser beam path length (several tens of meters), and development of a technology for adjusting the optical axis by feeding back the laser beam position in real time to prevent optical axis fluctuations during equipment operation. We have developed a technology to adjust the optical axis by feeding back the position of the laser beam in real time when the optical axis fluctuates during the operation of the equipment.

This paper presents the effect of P addition on the corrosion resistance of steels before and after rust formation. Electrochemical measurements and surface analysis of P-containing steels (Fe-0.5 mass% P, Fe-1.0 mass% P, and Fe-1.5 mass% P) were conducted to analyze the contribution of P to their initial corrosion resistance before rust formation. The results showed that the initial corrosion resistance of the steel was worse with higher P content. According to the surface analysis conducted by SEM/EDS, more P-segregations at grain boundaries existed with higher P content. Based on the results of polarization measurements, it was considered that these P-segregation became the initiation sites of localized corrosion, resulting in the decrease in the initial corrosion resistance.

Although the initial corrosion resistance was worse with higher P content, the long-term corrosion resistance was better with higher P content. According to the results of atmospheric exposure tests at Miyakojima and the surface analysis of rust layers, P was incorporated into the rust layer, and it promoted the protective ability against corrosion.

Ionic liquids are salts, and their melting points were less than 100 ºC under atmospheric pressure. In particular, ionic liquids, which melting point of them were less than room temperature under atmospheric pressure, have been researched in recent decades. Ionic liquids are well-known to designer’s solvents since configuration of cation and anion are easily to change then specificity is exhibited. In this work, novel protic ionic liquids (PILs) which are applied for CO₂ sorption materials have been synthesized using aromatic amine such as alkylpyridine derivatives and N,N-dimethylaniline and bis (trifluoromethanesulfonyl) amide due to co-existing proton conductivity and hydrophobicity. Synthesized PILs exhibited hydrophobicity since 1-octanol–water partition coefficients were more than 0. Also, their ionic conductivities were approximately 10⁻³ S cm⁻¹ at room temperature, and their mechanism of ionic conduction were different one compared with general electrolyte solution due to high viscosities. In addition, several PILs were high selectivity for CO₂ sorption compared with N₂. Furthermore, PILs gelatinized with bis[4-(1H,1H,2H,2H-tridecafluorooctyl)phenyl] terephthalates due to improvement of mobility. Some of gel–sol transition temperatures of 5 wt% gels were approximately 100 ºC. The driving force of gelation with ionic liquids might be an entropy driven. Sorption selectivity for CO₂ and N₂ were similar one before and after gelation.