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Vanadium is an extremely valuable industrial metal typically obtained from processing metallurgical slags. This article provides a comprehensive review and critical evaluation of the technologies of vanadium extraction from slags aiming to identify the most prospective technology. The review covers traditional approaches for treating V‐bearing slags, such as salt roasting followed by acid leaching and ammonium precipitation, as well as promising alternative methods in this field, such as bioleaching, ultrasound‐assisted leaching, and vaporization. The current industrial practice remains energy‐intensive and is associated with chemical waste generation, thus leaving room for further improvements. Overall, this work provides valuable insights into the recycling of vanadium from steelmaking slags including extraction efficiencies of industrial and lab‐scale methods, and discusses the advantages and disadvantages of each method setting the stage for future advancements in this field. The vaporization method is one of the most promising among those reviewed. [ABSTRACT FROM AUTHOR]

The mechanical properties of two metastable austenitic cast steels are examined by performing tensile tests in a temperature range of −70 to 300 °C. The 16‐6‐6 steel has an Ms temperature of −30 °C and an Md temperature of 100 °C. Athermal martensite formation down to −196 °C can be excluded for X3CrNiCuN17‐6‐4 steel. The Md temperature of X3CrNiCuN17‐6‐4 steel is 130 °C. The results obtained by a semiempirical thermodynamic‐mechanical calculation model are linked to experimental results from the tensile tests. The presented model combines chemical energy amounts from thermodynamic databases with mechanical energy amounts obtained by tensile tests with the aid of the conversion rule proposed by Patel and Cohen. Thermodynamic calculations are performed using the Thermo‐Calc software with the database TCFE10. As a result, the stress–temperature–transformation diagram showing the temperature dependence of proof stress, tensile strength, triggering stress for martensite formation, and the associated critical transformation temperatures (Ms,Md) is obtained. With the aid of the semiempirical thermodynamic‐mechanical model, it can be shown that the mechanical properties and critical temperatures of a metastable austenitic steel can be determined at very low experimental effort. [ABSTRACT FROM AUTHOR]

Herein, MgO–C refractory brick is immersed into the molten ladle slags with various CaO/Al2O3 ratios (located in the range of 0.56–0.78 and 1.99–1.36) and SiO2 addition from 1 to 20 wt%, at two temperatures of 1550 and 1650 °C. After the interaction with the slag with a CaO/Al2O3 ratio range of 0.56–0.78, the MgAl2O4 phase with various sizes is found to form in the solidified slag layer adhering to the MgO–C sample surface, and a layer consisting of MgAl2O4 on the interface of MgO–C brick is observed. For the slag with the CaO/Al2O3 ratio range of 1.99–1.36, a small amount of minor size of MgAl2O4 particle is detected only with 20 wt% of SiO2 addition. Instead of a formation of the MgAl2O4 layer, the Fe phase containing Mn, metallic Ti, and Si is scattered on the side of the solidified slag layer. The corrosion is more pronounced in the slag with a high CaO/Al2O3 ratio and is enhanced via the addition of SiO2 along with the increased solubility of MgO. The increased solubility of MgO in the slag with increasing SiO2 has also been predicted via FactSage. [ABSTRACT FROM AUTHOR]

Austenitic stainless steels have a wide area of applications, including spring steels in their hardened condition. A preceding forming process mainly achieves the necessary high yield strength (YS) for spring steel. During strain hardening, strain-induced α′-martensite formation results in high strength characteristics. The driving forces behind this transformation include low stacking fault energy of austenitic base material and high chemical driving force of α′-martensite formation. Both parameters are strongly dependent on temperature. This research represents the temperature dependent mechanical properties in a temperature range between −40 °C and 200 °C of a) nickel reduced manganese and nitrogen alloyed stainless steel X5CrMnNiMoN16-4-4 (4Mn) and b) CrNi steel X10CrNi18-8 (1.4310) at a strain rate of 4.6 × 10−4 s−1. Additionally, the effect of a moderate increase in strain rate to 9.2 × 10−4 s−1 and 6.7 × 10−3 s−1 on quasi-adiabatic heating of the steels was investigated. For both steels, by increasing the strain rate, the adiabatic temperature increases and subsequently decreases the strain-induced α′-martensite formation. The increase in the strain rate results in a strong drop of ultimate tensile strength (UTS) for both steels. Nevertheless, the uniform elongation (UE) remains almost constant at a high level for 4Mn. The UE decrease sharply in case of 1.4310. Independent of strain rate value, a larger strain-induced α′-martensite fraction generated in 4Mn compared with 1.4310. Consequently, under all experimental conditions, higher UTS values were achieved for 4Mn. The strain-induced α′-martensite was quantified by magnetic saturation analysis (MSAT). Subsequently, it was characterised by scanning electron microscopy (SEM) using electron channelling contrast imaging (ECCI) and electron backscatter diffraction technique (EBSD). [ABSTRACT FROM AUTHOR]

This study investigates the viscosity, density, surface tension, and crystallization behavior of two commercial mold fluxes that are utilized to cast ultralow‐carbon, low‐carbon, and medium‐carbon steel grades, as well as electric steels (high‐B magnetic and grain‐oriented steels). Experiments are performed in the temperature range of 1073–1673 K using the rotating bob method, maximum bubble pressure method, buoyancy method, and single hot thermocouple technique. The phase structure is investigated via scanning electron microscopy and X‐ray powder diffraction. The results indicate that viscosity and density exhibit nonlinear temperature dependence. Increased basicity (CaO/SiO2) results in reduced viscosity and elevates the break temperature of the mold fluxes. Furthermore, the incubation time required for phase formation decreases with increasing basicity. Finally, time–temperature transformation and continuous cooling transformation diagrams are constructed. [ABSTRACT FROM AUTHOR]

In this study, an austenitic CrMnNi–N steel is examined with regard to its solidification behavior of the weld metal. For this purpose, the cooling rate of the weld metal at different welding speeds is determined for tungsten inert gas welding without filler metal. The relationship between secondary dendrite arm spacing (λ2$\left(\lambda\right)_{2}$) and cooling rate (ε.$\overset{.}{\epsilon}$) can be described using λ2=18.56⋅ε.−0.269$\left(\lambda\right)_{2} = 18.56 \cdot \left(\overset{.}{\epsilon}\right)^{- 0.269}$. Moreover, the microstructure is characterized by a scanning electron microscope using energy‐dispersive X‐ray spectroscopy (EDS). Based on the EDS measurement, it is possible to describe the microsegregation of Cr, Ni, Mn, Mo, and N. The detected microsegregation behavior is compared with the results obtained from Thermo‐Calc calculations. The microsegregation varies depending on the present phase during solidification and correlate well with microstructure observations. By using the software Thermo‐Calc, the theoretical description of solidification is based on the classical Scheil model with fast diffusion of N. A primary ferritic solidification is calculated, which correlates with the experimental findings. [ABSTRACT FROM AUTHOR]

Drive motors for new energy vehicles require nonoriented silicon steel with high strength and excellent magnetic properties, which are always difficult to balance. In this study, the effects of Cu content on the precipitates, microstructure, and properties of nonoriented silicon steel are investigated. The results show that a dispersed and coherent nanoscale B2 Cu‐rich precipitates are formed when Cu addition is 0.91 wt%, while ε‐Cu precipitates with large size and low number density are formed with higher Cu addition. The nanoscale B2 Cu‐rich precipitates afford a higher precipitation strengthening contribution than the larger ε‐Cu precipitates via cutting mechanism. Concurrently, the nanoscale B2 Cu‐rich precipitates nominally affect the iron loss deterioration. With increasing Cu content, the average grain size decreased, while the favorable λ texture diminished, and the unfavorable γ texture increased. With the combined effect of the grain size, texture, and precipitates, the iron loss increased first slightly and then significantly with further Cu addition, whereas the magnetic induction gradually decreased. The comprehensive properties of the steel are optimal when Cu addition was 0.91 wt%, which yielded a yield strength of 571.2 MPa, an iron loss P1.0/400 of 20.05 W kg−1, and a magnetic induction B5000 of 1.621 T. [ABSTRACT FROM AUTHOR]

The remelting of Fe‐xTiC metal matrix composites (MMCs) is studied using the sessile drop method. This is to determine the conditions needed for the complete dissolution of TiC precipitates in the Fe‐based melt. Samples with different amounts of TiC (2, 3.5, and 5 wt%) are analyzed in a hot‐stage microscope (HSM), capturing the softening and melting temperatures. A Cr‐alloyed steel is selected as a matrix. Consequently, the presence of TiC elevates the melting initiation temperature above the melting point of pure iron (e.g., 1659 ± 10 °C for Fe‐5TiC). Furthermore, samples with higher TiC amounts exhibit higher melting initiation temperatures. This trend is confirmed by differential scanning calorimetry measurements, conducted on the representative Fe‐xTiC samples. Microstructural examinations of the solidified (HSM) samples identify two distinct TiC precipitate morphologies: primary blocky/cubic and secondary eutectic plate like. For instance, the Fe‐5TiC sample contains numerous blocky/cubic precipitates (7.5 ± 3.1 μm) clustered at the upper cross‐ section, while secondary plate‐like precipitates (20.4 ± 11.8 μm) are uniformly distributed in eutectic assemblies with the matrix. This study provides meaningful insights for optimizing the production of as‐cast and as‐atomized Fe‐TiC MMCs, particularly in selecting reinforcement levels and homogenization temperatures for complete TiC dissolution. [ABSTRACT FROM AUTHOR]

The thermophysical properties of an industrial blast furnace slag with varying TiO2, V2O3, and FeOx content are investigated using a rotating viscometer and maximum bubble pressure method at low oxygen partial pressure. The obtained experimental results are supported by thermodynamic calculations using FactSage 7.2 software and by scanning electron microscope analysis. The measurement outcomes clearly indicate that an increase in V2O3 and TiO2 content up to 10 wt% at 5 wt% FeOx leads to a decrease in the viscosity of all studied slags; however, with 15 wt% of V2O3 and TiO2, the viscosity changes insignificant. The presence of 10 wt% FeOx alters the behavior of the slags in the liquid‐dominant region. These changes in the break point temperature are consistent with the behavior of melilite and perovskite phases. Moreover, an increase in the FeOx, V2O3, and TiO2 increases the density of all studied slags within the temperature range of 1450–1650 °C. Additionally, introducing pure oxides to the slag reduces the surface tension of all the studied slags, confirming their role as a surfactant. [ABSTRACT FROM AUTHOR]

Cerium loss is difficult to be avoided during the electroslag remelting (ESR) process. To reduce the cerium loss in high‐speed steel during the ESR process, the present study investigates the thermodynamics of cerium oxidation in cerium‐containing high‐speed steel based on the thermodynamic calculation and laboratory‐scale steel–slag reaction experiments. The results show that the reactions between [Ce] and (Al2O3), as well as [Ce] and (MgO) contribute to the cerium loss in the steel. Increasing the contents of CaF2 and MgO in the slag, the activities of Al2O3 and Ce2O3 show a slightly decreasing trend. The addition of CaO and Ce2O3 significantly reduces the Al2O3 activity but enhances the Ce2O3 activity. MgO activity shows an insignificant change with the contents of CaO and Ce2O3, while it decreases with adding Al2O3 and CaF2. Reducing Al2O3 content and enhancing Ce2O3 content in the slag are feasible to increase the cerium yield in the steel. With increasing Al2O3 content from 16.93 to 26.92 wt%, the cerium yield decreases from 8.4% to 6.0%. Increasing Ce2O3 content from 3.98 to 11.01 wt% enhances the cerium yield from 6.0% to 16.9%. The actual soluble Ce content in equilibrium with slag is almost less than 0.001 wt%. [ABSTRACT FROM AUTHOR]

Accurate data on the high‐temperature thermophysical properties, which are density, surface tension, and viscosity, are indispensable for performing high‐precision casting simulations of Ni‐based superalloys. Viscosity is the most important thermophysical property for thermofluidic analysis. However, measuring the viscosity of an alloy, which is lower than that of molten glass, is difficult, and experimental viscosity data are limited. Herein, the density of Ni‐based superalloys is measured using the maximum bubble pressure (MBP) method to determine viscosity. The viscosity is evaluated using the oscillating crucible method. The surface tension is simultaneously measured using the MBP method. In these results, the average density values [kg m−3] of Alloy 65, Alloy 718, Alloy WA, and Alloy 720 are 7.52 × 103, 7.43 × 103, 7.82 × 103, and 7.52 × 103, respectively. The average surface tension values [N m−1] of Alloy 65, Alloy 718, Alloy WA, and Alloy 720 are 1.55, 1.54, 1.47, and 1.51, respectively. The fitting equations of the molten Ni‐based superalloys are as follows. 1) Alloy 65: ln(η [mPa s])=6569×(1θ [K])−1.844$$ \mathrm{ln}(\eta  [\text{mPa} \text{s}])=6569\times \left(\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$\theta  [\text{K}]$}\right.\right)-1.844$$; 2) Alloy WA: ln(η [mPa s])=6097×(1θ [K])−1.621$$ \mathrm{ln}(\eta  [\text{mPa} \text{s}])=6097\times \left(\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$\theta  [\text{K}]$}\right.\right)-1.621$$; 3) Alloy 720: ln(η [mPa s])=6179×(1θ [K])−1.700$$ \mathrm{ln}(\eta  [\text{mPa} \text{s}])=6179\times \left(\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$\theta  [\text{K}]$}\right.\right)-1.700$$; 4) Alloy 718: ln(η [mPa s])=6344×(1θ [K])−1.724$$ \mathrm{ln}(\eta  [\text{mPa} \text{s}])=6344\times \left(\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$\theta  [\text{K}]$}\right.\right)-1.724$$. [ABSTRACT FROM AUTHOR]

The application of hydrogen as a reducing agent in existing blast furnaces presents a promising avenue for significantly reducing emissions. The current emphasis on hydrogen reduction may necessitate a review of parameters such as the temperature, chemical composition, porosity, reduction time, and reducing agent. In this study, the impact of varying the temperature of reducing iron ore pellets in hydrogen is focused on. A mercury intrusion porosimeter is used to assess the porosity postreduction. The microstructure of the reduced pellets is analyzed with the help of scanning electron microscopy. Notably, the pore size and overall porosity are higher at higher temperatures. Using an X‐ray diffractometer, it is determined that Fe2O3 is reduced to Fe across all specified temperatures at different reduction times. The maximum degree of reduction is attained at 1000 °C while the minimum degree of reduction is attained at 700 °C. Considering these characteristics, researchers in the field can identify the optimal conditions, develop strategies, and advance technologies that contribute to the production of environmentally friendly steel. [ABSTRACT FROM AUTHOR]

The interaction between the industrial ladle lining bricks (carbon = 5-13 mass%) and secondary metallurgical slag (CaO/Al 2 O 3 ratio = ~1; SiO 2 = 1–20 mass%) was evaluated under laboratory conditions using finger testing between 1550 and 1650 °C. The thermophysical properties, including viscosity, density, and surface tension of the three slags were measured and compared with previously reported data. The experimental investigations were supported by thermochemical modelling (Factsage 7.2). The three lining materials exhibited different wear behaviour when in contact with each of the three slags at different temperatures. The slag with 1 mass% SiO 2 was MgO-saturated and had a low viscosity compared to the slags with 10 and 20 mass% SiO 2. This slag effectively infiltrated the lining without dissolving it at 1550 °C. With increasing temperature, the MgO saturation in the slag decreased, which led to the dissolution of the MgO grains from the mining bricks into the slag. Further, the carbothermal reaction began to dominate at higher temperatures, which led to carbon oxidation and the formation of new MgO. A solid spinel phase was observed in the slag with 10 mass% SiO 2 below 1600 °C and in the slag with 20 mass% SiO 2 at all investigated temperatures. Interaction with the lining materials intensified this spinel formation, which slowed or stopped slag infiltration. The high content of impurities in the lining material (e.g. SiO 2 , CaO, and Fe 2 O 3) led to the formation of a liquid slag phase on the grain boundary, which compromised the strength of the material and caused the loss of MgO grains. [ABSTRACT FROM AUTHOR]

The plastic deformation and martensite evolution of austenitic CrMnNi–N stainless steel with 8.6 wt% Mn and 4 wt% Ni is investigated in a temperature range of −40 to 100 °C. Martensite evolution is determined by in situ magnetic measurements during tensile test. The triggering stress and strain for martensite formation decrease with decreasing temperature. Ex situ volumetric magnetic measurements are used to determine the strain‐induced α′‐martensite volume fractions. The characterization of the microstructure is carried out with scanning electron microscope. Using electron backscatter diffraction, strain‐induced α′‐martensite is detected within deformation bands in the austenite. The strain hardening curve at −40 °C shows a typical progression for metastable austenitic stainless steels with pronounced strain‐induced α′‐martensite formation and can be divided into four hardening stages. At this temperature, the studied steel achieves the highest strain hardening rate. The amount of martensite increases with decreasing test temperature and reaches a maximum volume fraction of 76 vol% at −40 °C. The highest ductility of 83% is achieved at 40 °C, accompanied by a tensile strength of 732 MPa. The in situ magnetic measurement confirms that the inflection point in the strain hardening curve coincides with the maximum martensite formation rate. [ABSTRACT FROM AUTHOR]

The need to develop green steelmaking techniques has led to the replacement of reducing agents such as CO with H2. H2 and N2/H2 mixtures can be used for the carbothermal reduction of iron ore. Herein, the reduction swelling index (RSI) of iron ore pellets in a forming gas (N2/H2) atmosphere at temperatures of 700–1000 °C is investigated and it is compared with that in pure H2. It is showed in the experimental results that the RSI increases with increasing temperature for both the H2 and N2/H2 atmospheres. The maximum swelling is reached approximately 5 min into the H2 reduction process, while in the N2/H2 atmosphere, it is reached after 25–45 min of reduction, depending on the temperature. When the reduction temperature exceeds 900 °C, the RSI is greater than 20%. Scanning electron microscopy/energy‐dispersive X‐ray spectroscopy is performed to detect the changes in the microstructure and chemical composition of the samples. The nonreduced areas in the reduced pellets during the N2/H2 reduction process are analyzed using light optical microscopy. [ABSTRACT FROM AUTHOR]

Direct reduction of iron ore (DRI) is gaining an increased attention due to the growing need to decarbonize industrial processes. The current industrial DRI processes are performed using reformed natural gas, which results in CO2 emission, although it is less than carbothermic reduction in the blast furnace. Carbon‐free reduction may be realized through the utilization of green H2 as a reducing agent, in place of natural gas. Herein, the effects of various gas mixtures and temperature on the reduction kinetics of the hematite iron‐ore pellets are focused on in this work. Pellets are reduced at 700, 800, 850, and 900 °C in hydrogen and using various gas mixes at 850 °C. Morphology of the pellets is investigated with the help of scanning electron microscopy and mercury intrusion porosimetry. The effects of temperature and gas composition on the reduction kinetics and porosity of the pellets are discussed. A notable effect of reduction rate on the internal structure of the pellets is detected, slower reduction rate yielded bigger pores offsetting the gas composition. Higher temperature results in coarser pores and higher porosity. Increase of CO content in the gas mix also leads to bigger pore size. [ABSTRACT FROM AUTHOR]

Liquid slag properties are essential for understanding complex mass and momentum phenomena in metallurgical operations. The density, surface tension and viscosity were measured in six silicate-rich slags of the CaO–SiO 2 and CaO–SiO 2 -'Fe 2 O 3 ' tot systems by combining the maximum bubble pressure and rotating bob methods. The properties investigated were sensitive to the temperature, SiO 2 and Fe 2 O 3 contents. Different experimental trends were derived due to the amphoteric properties of Fe 2 O 3. The slags with ferric oxide were denser than the silicate melts. Surface tension gradually decreased with temperature and indicated firstly a rise and then decline with further Fe 2 O 3 addition. Raman spectra were analyzed to provide structural information of the polymer melt and indicated an enhancement in the polymerization degree with Fe3+. The derived experimental trends and role of Fe3+ in the silicates were attributed to the interplay of complex factors: different bonding in the melt, cation interactions and the oxidation state of iron. The influence of Fe3+/Fe2+ on the melt properties was discussed. [ABSTRACT FROM AUTHOR]

The study evaluates the effect of electrochemical hydrogen charging on the tensile properties and fracture behavior of the plasma tungsten inert gas weld of the high‐alloy austenitic steel X3CrMnNiMoN17‐8‐4 in comparison to the pure base metal (BM). The weld metal exhibits a higher susceptibility to hydrogen embrittlement than the BM, which is mainly expressed by a loss in ductility. Based on the performed electron backscatter diffraction and X‐ray diffraction examinations, this is attributed to the higher amount of δ‐ferrite and the higher dislocation density in the weld zone. Furthermore, fractographic analyses reveal a change in the manner of fracture mode from ductile to brittle fracture starting from the edge in the hydrogen charged samples. The wider area of brittle fracture in the weld seam in relation to the BM indicates that hydrogen penetrates deeper into the material. Consequently, the diffusivity of hydrogen in the weld seam is determined to be significantly higher than in the BM. [ABSTRACT FROM AUTHOR]

The influence of Al2O3 in the range of 10–20 mass% and TiO2 in the range of 0.55–5 mass% on the flow behavior, viscosity, density, and surface tension of molten industrial blast furnace slag with CaO/SiO2 = 1.13 is investigated using a high‐temperature microscope, a rotating viscometer, and the maximum bubble pressure method. The measurement results show that Al2O3 acts as a network former in the studied CaO–SiO2–MgO–Al2O3–TiO2 slags. With an increase in the Al2O3 content from 10 to 20 mass%, the viscosity and surface tension of the slags increase and the density decreases. In contrast to Al2O3, the TiO2 acts as a surfactant and network breaker in the range of up to 15 mass%. The addition of TiO2 up to 15 mass% results in a decrease in the viscosity in the liquid‐dominated region and a decrease in the surface tension of the studied slags. Therefore, the density increases with the addition of TiO2 due to increasing molar volume. The behavior of the breakpoint temperature on all the viscosity curves is in complete agreement with the behavior of the flow point temperature and crystallization temperatures of melilite and perovskite. [ABSTRACT FROM AUTHOR]

The present study deals with the pitting and repassivation behavior of a nickel‐reduced austenitic stainless steel with different nitrogen contents. While nitrogen promoted the resistance to pitting, no significant effect on repassivation was found. The study also aims to address the experimental difficulties in determining repassivation potentials owing to the occurrence of crevice corrosion. Furthermore, the mechanism of the ongoing reactions was investigated, indicating that pitting was initiated in regions where manganese sulfide inclusions were present next to the remaining δ‐ferrite. [ABSTRACT FROM AUTHOR]

Austenitic steels are known to exhibit a low hydrogen diffusion coefficient and hence a good resistance to hydrogen embrittlement. Therefore, it is an experimental challenge to investigate their hydrogen diffusion properties. In this study, the electrochemical permeation technique is used to determine the hydrogen diffusion coefficients in different pre-deformed states (φ = 0, 0.32, 0.39, 0.49) of the high-alloy austenitic TRIP steel X3CrMnNiMoN17-8-4 in a temperature range of 323 K–353 K. In combination with microstructural analysis, a correlation between phase transformation from γ-austenite to α′-martensite and dislocation density is shown. As a result of the lattice transformation from fcc to bcc, the diffusion rate of hydrogen is significantly increased (D app, φ = 0 = 3.6 × 10−12 cm2 s−1, D app, φ = 0.32 = 1.6 × 10−11 cm2 s−1at 323 K). With higher degrees of deformation, the dislocation density also increased in the martensite islands, resulting in a degressive growth of the diffusion coefficient (D app, φ = 0.39 = 5.3 × 10−11 cm2 s−1, D app, φ = 0.49 = 1.1 × 10−10 cm2 s−1at 323 K). Moreover, detailed calculations are performed to describe the way of hydrogen trapping and to give a possible mechanism of diffusion. [Display omitted] • Diffusion coefficients of H in austenitic steel (e.g. D 323 K = 3.6 × 10−12 cm2 s−1). • Accelerated hydrogen diffusion due to strain-induced α′-martensite formation. • Amount of trapped hydrogen strongly decreases with increasing temperature. • Solubility of hydrogen significantly decreases with increasing α′-martensite. [ABSTRACT FROM AUTHOR]

To investigate the possible reactions between carbon-bonded ceramics and liquid Armco iron, three types of carbon (10 wt% C) bonded ceramics Al 2 O 3 rich spinel (C-AR78), MgO rich spinel (C-MR66), and CaO·6Al 2 O 3 (C-CA6) were put into contact with liquid Armco iron at 1625 °C by using the sessile drop method. During the interaction experiments, the oxygen partial pressure values in the experimental chamber were monitored with an oxygen detector. Thereby, the oxygen partial pressures differed based on the used carbon-bonded ceramic. It was found that the iron samples after interaction experiments were covered by newly formed oxide layers, and oxide whiskers have grown at the interface with the ceramic substrates. The compositions of the newly formed oxide layers and whiskers were related to the applied ceramic substrates. Moreover, Al and C pick-up into the iron sample was observed. The obtained results were discussed with a thermodynamic simulation based on the available Al-Fe-Mg-O - database. [ABSTRACT FROM AUTHOR]

Metallic material concepts associated with the sustainable and efficient use of resources are currently the subject of intensive research. Al addition to steel offers advantages in view of lightweight, durability, and efficient use of high-Fe scrap from the Al industry. In the present work, Al was added to Fe-12Cr-(9,12)Ni-3Mn-0.3C-xAl (x = 0.1–6) (wt.%) stainless steels to assess its influence on microstructure and mechanical properties. According to density measurements based on Archimedes' principle, densities were between 7.70 and 7.08 g/cm3. High-energy X-ray diffraction estimations of the lattice parameter indicated that nearly 31% of density reduction was caused by the lattice expansion associated with Al addition. Depending on Al concentration, austenitic and duplex matrix microstructures were obtained at room temperature. In the presence of up to 3 wt.% Al, the microstructure remained austenitic. At the same time, strength and hardness were slightly enhanced. Al addition in higher quantities resulted in the formation of duplex matrix microstructures with enhanced yield strength but reduced ductility compared to the austenitic alloys. Due to the ready formation of B2-(Ni,Fe)Al intermetallics in the ferrite phase of the present alloy system, the increase in strength due to the presence of ferrite was more pronounced compared to standard duplex stainless steels. The occurrence of B2 intermetallics was implied by dilatometry measurements and confirmed by electron microscopy examinations and high-energy X-ray diffraction measurements. [ABSTRACT FROM AUTHOR]

Herein, the effect of the ordered phases and microstructure of 6.5 wt% Si electrical steel recrystallized and quenched at different cooling rates on its iron loss is investigated. The varied cooling rate barely influences the grain size and the precipitation of Cu but affects the magnetic domain significantly. A higher cooling rate is associated with greater residual stress and hence, leads to an increase in the width of the magnetic domain. In terms of the ordered phases, the quantity of B2 first decreases and then increases with a rising cooling rate while the quantity of D03 decreases. Meanwhile, the size of B2 antiphase domains reduces, while the D03 antiphase domains are either too fine to be observed or absent at higher cooling rates. The increased residual stress, the refinement of B2 antiphase domains, and the associated larger pinning effect on the migration of magnetic domain walls jointly lead to higher hysteresis loss. In addition, the increased width of the magnetic domain results in a larger anomalous loss. Both effects give rise to an overall increase in the iron loss P10/50. [ABSTRACT FROM AUTHOR]

• In the current paper, newly sintered ceramic substrates with various compositions (Al 2 O 3 ∙MgO, CA 6, CaZrO 3 , AZT (Al 2 O 3 based substrates containing ZrO 2 and TiO 2)) were tested in contact with liquid Armco iron under a low oxygen partial pressure in the heating microscope. • The most of the tested substrate showed no reaction with molten iron, except for AZT substrate. The formed reaction layer containing Fe, Si and Mn which were transferred from iron side. • Non-metallic inclusions before and after the experiments were analysed using an automatic scanning electron microscope combined with an energy dispersive X-Ray spectroscope. The total number of the inclusions in the iron samples after all interaction experiments greatly decreased. The deposition and agglomeration of inclusions, and the evaporation of some elements were the factors for the inclusions decreasing. • The stability of oxides consisted of substrates under low oxygen partial pressure was confirmed by the thermodynamic calculation. Ceramic substrates (Al 2 O 3 ·MgO, CA6, CaZrO 3 , AZT (Al 2 O 3 based substrates containing ZrO 2 and TiO 2)) were interacted with liquid Armco iron under a low oxygen partial pressure in the heating microscope. No noticeable dissolution of the ceramic substrates and reaction was observed for most of the substrates. Furthermore, deposition of SiO 2 and Fe was found on the cross section between iron and these substrates. However, for the substrate AZT, a reaction layer of complex composition was found on the interface between the iron sample and the AZT substrate. After all experiments, the total number of inclusions in the iron samples greatly decreased. The deposition, agglomeration of inclusions, and the evaporation of some elements were the factors for the inclusions decreasing. Furthermore, the stability of oxides consisted of substrates under low oxygen partial pressure was confirmed by the thermodynamic calculation. [ABSTRACT FROM AUTHOR]

The present study investigates the wetting behavior of Cr–Mn–Ni-alloys with TRIP/TWIP-effects on the hBN-SiC-ZrO 2 -substrate using the sessile drop method. The wetting behavior was studied in a 90 vol% N 2 /10 vol% H 2 atmosphere in the temperature range of 1500 °C–1600 °C. Experiments were conducted in the reactive steel/ceramic system. Results demonstrate the effect of the nickel and the sulfur content on the contact angle between hBN-SiC-ZrO 2 -substrates and Cr–Mn–Ni-alloys. The increase in the nickel content from 3 to 9 mass% caused the increase of the contact angle from 129 to 138° at 1600 °C. Whereas, the increase in the sulfur content caused the decrease of the contact angle. The contact angle of the melts alloyed with the sulfur increases as the temperature rises. The increase in the contact angle was related to the evaporation of the manganese. In addition, the study discusses the chemical reaction between the hBN-SiC-ZrO 2 -substrate and Cr–Mn–Ni-alloys through (i) SEM-EDX investigations and (ii) thermodynamic calculations. The SEM-EDX analysis of the steel/ceramic interface shows the chemical degradation of the hBN-SiC-ZrO 2 -substrate. As a result of the reaction, a transition layer with a thickness of around 0.7 mm was formed in the hBN-SiC-ZrO 2 -substrate. To characterize the chemical reaction, thermodynamic calculations were conducted using the Thermo-Calc software. Results show that the chemical reaction was caused by the chemical instability of the SiC with regard to elements in Cr–Mn–Ni-alloys. [ABSTRACT FROM AUTHOR]

Calcium aluminate system is widely used in several ceramic and metallurgical materials and processes such as tundish and mold slags for continuous casting process. In the case of mold powders, they play significant role during the steel solidification process and knowing its physicochemical properties is crucial in the study of slag behavior. In this context, the crystallization tendency of the mold powders plays a significant role in essential properties such as viscosity—which is fundamental to the efficiency of the casting process. In the present study, the effect of a water vapor atmosphere on the crystallization behavior of the CaO‐Al2O3 join is investigated using the single hot thermocouple technique. Distinct crystallization behaviors in presence of water vapor atmosphere are observed, according to the temperature range. Hindering of crystallization onset occurs at a temperature range above 1150 °C. For the temperature range below 1150 °C, crystallization improvement can be observed. The resulting time–transformation–temperature diagrams show the influence of temperature on the effect of water vapor upon crystallization, denoting the amphoteric nature of water. [ABSTRACT FROM AUTHOR]

The phosphorus partition between the unkilled liquid crude steel and the high basicity (CaO/SiO2 = 4.2), basic oxygen furnace (BOF) slags with varying compositions of Al2O3, TiO2, and MnO is studied at temperatures 1600 and 1650 °C. The tests are conducted in both "slag‐to‐metal" and "metal‐to‐slag" directions and for durations of 30 and 60 min. The measured results are compared with the values reported in literature and found to be in good agreement with some of them. It is found in the investigation of high‐basicity BOF slags, that Al2O3, MnO, and TiO2 lower the phosphorus partition. The phosphorus partition increases with increasing optical basicity. The phosphorus partition shows a maximum when the FeO content is in range of 25–30 mass%. The MgO content slightly increases the phosphorus partition. [ABSTRACT FROM AUTHOR]

Herein, considerable insight is provided into the evolution of strain‐induced martensite and mechanical properties of Fe–19Cr–4Ni–3Mn–0.15N–0.15C wt% austenitic stainless steel (in short Cr19NC15.15) during deformation at room temperature and cryogenic temperatures. In situ magnetic measurements of the martensite evolution during tensile tests at various temperatures are conducted. The triggering stress σtrigg.γ→α′ required for strain‐induced martensite formation is determined at the minimum in the strain hardening curve. It is found that with reducing deformation temperature in the range from 0 to –20 °C σtrigg.γ→α′ slightly decreases, whereas the triggering stress σtrigg.γ→α′ increases with further reduction of deformation temperature to −70 °C. The relation between the formed α′‐martensite fraction and the strain applied during tensile test is established. The results demonstrate that a reduced deformation temperature from room temperature (RT) to −70 °C significantly enhances the transformation rate and the total volume fraction of strain‐induced α′‐martensite. The yield and tensile strength increase whereas elongation continuously decreases due to an increasing α′‐martensite volume fraction with decreasing tensile test temperature. The α′‐martensite formation kinetic follows Olson and Cohen's model and are in good agreement between the in situ experiment and theoretical calculations. [ABSTRACT FROM AUTHOR]

The study aims to investigate the possible effect of glass transition firstly on the thermal conductivity of the CaO-B 2 O 3 system. The addition of CaO was varied in the range of 0 to 40 mass %. The transient hot-wire method, transient hot-strip method, laser flash method and the thermoreflectance method were applied for the investigation in the temperature range of 298 K to 1175 K. Positive temperature dependence was found for the 38mass %CaO-B 2 O 3 sample, which is the same as reported for B 2 O 3. However, slopes of the temperature dependence change just above the respective glass transition temperature. The addition of CaO to B 2 O 3 leads to the increase of thermal conductivity. The study discusses the possible structural change of B 2 O 3. [ABSTRACT FROM AUTHOR]

Thermophysical properties of liquid metal alloys play a crucial role in the variety of processes. Present work reports experimental investigations of two new transformation induced plasticity (TRIP) steels. A classical maximum bubble pressure technique is successfully used to measure surface tension and density of the liquid TRIP‐steel samples in the temperatures range of 1500–1800 °C. Experiments are performed in two different measurement cells from TU Freiberg and Commissariat a l'Energie Atomique (CEA), Cadarache. Capillaries are made of zirconia partially stabilized with yttrium oxide, and the samples are molten in Al2O3 crucibles. Measurements are conducted under the argon atmosphere. Surface tension of the investigated samples rises up to 1700 °C and further remains the same. Density of the new steels obtained in this study is in good agreement with the previously reported values for Fe–Cr alloys with similar Cr content. Density of the alloy is estimated as 875 488–11 885 × T (±218.85 kg m−3) for a 15%Cr alloy and 796 042–06 897 × T (±199 kg m−3) for a 19%Cr alloy. [ABSTRACT FROM AUTHOR]

By time-of-flight (TOF) neutron diffraction experiments, the influence of segregation-induced microstructure bands of austenite (γ) and martensite (α′) phases on the partitioning of stress and strain between these phases was investigated. Initially, tensile specimens of a Co-added stainless steel were heat treated by quenching and partitioning (Q&P) processing. Tensile specimens were subsequently loaded at 350 °C parallel to the length of the bands within the apparent elastic limit of the phase mixture. Lattice parameters in both axial and transverse directions were simultaneously measured for both phases. The observation of a lattice expansion for the γ phase in the transverse direction indicated a constraint on the free transverse straining of γ arising from the banded microstructure. The lateral contraction of α′ imposed an interphase tensile microstress in the transverse direction of the γ phase. The multiaxial stress state developed in the γ phase resulted in a large deviation from the level of plastic strain expected for uniaxial loading of single phase γ. Since segregation-induced banded microstructures commonly occur in many engineering alloys, the analysis of stress and strain partitioning with the present Q&P steel can be used to interpret the observations made for further engineering alloys with two-phase microstructures. [ABSTRACT FROM AUTHOR]

Thermo-physical properties of the liquid metals and alloys play an essential role in modeling and controlling metallurgical processes. In particular, surface tension of metals has a strong impact on wetting various surfaces. Boron is added in numerous iron-based alloys as micro-alloying component. In existing literature, there is no general agreement with the effect of boron on the surface tension. The present study focuses on investigations of boron micro-alloying on the surface tension of iron and CrMnNi alloys by the maximum bubble pressure method (MBP). In contrast to other techniques, maximum bubble pressure technique is less affected by the evaporation of surface-active elements and the purity of the atmosphere around the sample. Measurement of the surface tension was accomplished before and after in situ addition of boron to the molten metal phase. Samples were molten in ZrO2 and Al2O3 crucibles and yttria-PSZ capillaries were used for the experiments. Measurements were carried out at 1550 °C in argon atmosphere and argon as bubbles formation media. Results of the experiments indicate a minor effect of boron on the surface tension of liquid iron. Effect of boron on the surface tension of steels is discussed in the context of other surface-active elements present. [ABSTRACT FROM AUTHOR]

The role of B2O3 as a fluxing agent for developing fluoride free fluxes has been accentuated in the recent years. Therefore, knowledge about thermophysical properties of the oxide are essential to find the optimal chemical composition of the mold fluxes. In the present study, the density and thermal conductivity of B2O3 were measured by means of the buoyancy method, the maximal bubble pressure (MBP) method and the hot-wire method in the temperature range of 295-1573 K. The results are discussed in the context of the chemical stability of the B2O3 as well as the effect of glass transition on the thermal conductivity. The density of the B2O3 decreases non-linearly with increasing temperature in the temperature range of 973-1573 K. The MBP method was successfully applied for the density measurements with a viscosity up to 91 Pa.s. The thermal conductivity of the B2O3 in the solid and molten states increases with increasing temperature. Based on the Kittel's equation, the temperature dependence of the thermal conductivity through the glass transition temperature of B2O3 was discussed. [ABSTRACT FROM AUTHOR]

The viscosity and flow behavior of the industrial heterogeneous highly basic BOF slags with 2 and 8 mass% MgO and 0 to 25 mass% V 2 O 5 were measured by using rotating bob method and hot stage microscope. An increase in the content of V 2 O 5 in slags with 2 mass% MgO led to a slight increase and then a decrease in viscosity. While, in the case of 8 mass% MgO-containing slags, their viscosity decreased with increasing V 2 O 5 content in liquid determined region. Thereby, the behavior of flow point temperature and crystallization temperatures corresponds with the behavior of critical temperature on the viscosity curves for both groups of slags. The NBO/T results revealed a polymerization with the increasing of V 2 O 5 in both slags groups with 2 and 8 mass% of MgO. Moreover, the formation of solid particles at break point in quenched slags were investigated. [ABSTRACT FROM AUTHOR]

Stainless steels are commonly used in hydraulic components where they may be susceptible to cavitation erosion. In this study the cavitation erosion resistance of AISI 420-type stainless steel is examined after quenching and partitioning (Q&P) heat treatment. Q&P-samples were prepared with varying heat treatment parameters, and their initial properties were examined with X-ray diffraction and hardness measurements. Reference samples were also prepared with quenching and tempering and quenching without partitioning. The samples were eroded for 6 h with an ultrasonic cavitation erosion device, and their mass losses were measured. The eroded areas were examined with scanning electron microscopy, optical profilometry, and magnetic induction measurements. The results suggest that the cavitation erosion resistance of the examined stainless steel can be significantly enhanced with Q&P. This enhancement of cavitation erosion resistance results from high initial hardness and retained austenite fraction of the steel. During cavitation erosion the retained austenite can absorb cavitation bubble collapse energy by transforming into strain induced martensite, which increases the hardness of the steel and generates expansion of the lattice. This expansion additionally hinders crack propagation at grain boundaries, which reduces the formation of initial cavitation damage. • Quenched and partitioned AISI 420 stainless steel was eroded with cavitation. • Cavitation erosion resistance was improved compared to quenching and tempering. • Cavitation erosion resistance depends on hardness and retained austenite fraction. • Strain induced martensitic transformation was identified as beneficial mechanism. [ABSTRACT FROM AUTHOR]

[Display omitted] • Optimal rolling processes promoted the uniform microstructure, leading to low iron loss. • Optimal rolling processes furthered magnetic induction with λ-fiber and α* texture. • Great mechanical and magnetic properties were obtained by coherent Cu-rich clusters. A bottleneck in the development of high-strength non-oriented silicon steels for drive motors of new energy vehicles is the balance of strength and magnetic properties. This paper successfully tackled this problem through the optimization of thickness reduction for hot and cold rolling and the formation of coherent precipitates using a Cu-alloyed non-oriented silicon steel. More specifically, a thickness reduction of 96% in the course of hot rolling promoted the homogenization of microstructure during the following normalization treatment. Subsequently, a deformation degree of 80% during cold rolling ensured the inheritance of the uniform microstructure and inhibited the abnormal growth of recrystallized grains during annealing, thereby suppressing the iron loss to a value as low as 15.6 W/kg. At the meantime, this combined process promoted the inheritance of λ-fibers and the formation of {114}〈481〉 texture in the annealed sheet, improving the magnetic induction intensity B 50 to 1.606 T. In addition, under the joint effect of a variety of strengthening mechanisms, the yield strength of this annealed sheet reached 668 MPa. A pronounced increase in strength, about 207 MPa, was derived from precipitation hardening by the great difference in the modulus between coherent Cu-rich clusters and the α-Fe matrix. [ABSTRACT FROM AUTHOR]

The effect of MgO and low TiO2 content on the solidification of CaO–SiO2–Al2O3 based mold fluxes is investigated. The crystallization and viscosity behaviors are analyzed using single hot thermocouple technique (SHTT) and rotating viscometer, respectively. Continuous‐cooling‐transformation (CCT) results point to an increase of critical cooling rate (CCR) with increasing MgO content. Conversely, the presence of TiO2 seems to mitigate the effect of MgO on the crystallization due to the strong glass former characteristic of titanium dioxide. Viscosity measurements show an increase with increasing MgO content in slags containing TiO2. Break temperatures (Tbr) are compared to the onset crystallization temperatures from CCT experiments. Scanning electron microscopy (SEM) and X‐ray diffraction (XRD) analysis results indicate the presence of melilite (Al2Ca2Mg0.5O7Si1.5) for all samples of mold flux containing both MgO and TiO2. [ABSTRACT FROM AUTHOR]

The accurate prediction of the elastic modulus of aluminum foam is important for the application in high-tech fields, e.g. in aerospace industry. However, the scaling law based on the Gibson-Ashby model did not achieve the precise prediction of elastic modulus, in absence of complex porous structural features. In this study, we extended the scaling law by introducing the topological and morphological parameters into the multivariate equation. The 3D numerical images of aluminum foam specimens were obtained by X-ray tomography method, and the nine structural parameters were calculated and analyzed. The results show that as the porosity increases from 77% to 91%, the highest frequency of sphericity and solid material thickness of the cellular structure remains practically constant, although the distribution of cell size becomes more dispersed. The edges connections and the Inter-Branches Angle (IBA) of aluminum foam remain unchanged for all the specimens. Seven structural parameters were introduced into the extended scaling law to predict the elastic modulus with a higher residual value R 2 of 0.932, in contrast to the R 2 of 0.702 for the conventional scaling law. Through a stepwise linear regression method, the extended scale method was simplified by removing redundant parameters, and still achieved the elastic modulus predictions with a residual value R 2 of 0.929. The remaining structural parameters in the extended scaling law, i.e. relative density, solid material thickness, and sphericity, were supposed to independently influence the elastic modulus, according to the covariance analysis. The three independent parameters offer the possibility to accurately predict and regulate the mechanical properties of aluminum foam. • The scaling law is extended by combining the cellular structure parameters. • Accurate prediction of the elastic modulus of Al foam is achieved with R 2 of 0.932 • Three of these structural parameters independently influence the elastic modulus. • The node connectivity features of aluminum foam coincide with trabecular bone. [ABSTRACT FROM AUTHOR]

Solidification and segregation behavior of a novel X3CrNiCuN17-6-4 (concentrations in wt.%) cast steel was studied by thermodynamic calculations and corresponding microstructure investigations. In addition, resulting mechanical properties were examined by tensile tests in a temperature range of −60 to 200 °C and compression tests were performed with varying strain rates ranging from 1 s−1 to 10−4 s−1 at room temperature. The investigated steel showed an anomalous temperature dependence of tensile elongation, which is a typical characteristic of high alloy TRIP/TWIP steels. In the as-cast state before heat treatment, a few micrometer-sized copper precipitates were visible, which were exclusively located in the interdendritic regions. A solution annealing was performed at 1050 °C for 30 min to dissolve nitrides and carbides likely to be present in the as-cast microstructure. However, in areas with a high copper content further nanometer-sized copper precipitates were formed after heat treatment. EDS point measurements and EPMA were used to determine the chemical composition of dendrites, interdendritic regions and copper precipitates before and after solution annealing. While the enrichment of chromium and copper in interdendritic regions could be verified by the thermodynamic calculations, the enrichment of nickel in interdendritic regions contradicted the predictions according to Scheil calculation. [ABSTRACT FROM AUTHOR]

An Al-alloyed Fe–Cr–Ni–Al–Mn–C ferritic stainless steel exhibited a high apparent coefficient of thermal expansion during continuous heating in the temperature range of 800–1050 °C. The anomaly was ascribed to the matrix lattice expansion associated with the dissolution of (Ni,Fe)Al precipitates with a B2-CsCl crystal structure. The expansion was justified on the basis of the Al and Ni enrichment of the ferritic matrix as the precipitates dissolved. [ABSTRACT FROM AUTHOR]

The deformation-induced formation of α′ martensite was investigated by tensile testing of a Fe-19Cr-3Mn-4Ni-0.15C-0.17N cast austenitic steel between −196 °C and 400 °C. The steel did not exhibit spontaneous α′ martensite formation at temperatures as low as −196 °C. Therefore, the critical driving force for the formation of α′ (−2780 J/mol) was obtained by determining the complementary mechanical energy necessary to trigger the deformation-induced α′ martensite at 0 °C. Driving forces for the γ→α′ transformation at other tensile test temperatures associated with the deformation-induced α′ formation were then obtained by subtracting the mechanical energies applied to trigger the martensitic transformation from the critical driving force. The triggering mechanical energies were obtained from in-situ magnetic measurements which enabled to mark the onset of the γ→α′ transformation. The driving forces for the γ→α′ transformation calculated using the preceding method indicated an increase in the stability of austenite which was attributed to changes in the mechanical and physical properties of austenite in the vicinity of the Néel temperature. The method can be used to calculate modified driving forces for the occurrence of the γ→α′ phase transformation. [ABSTRACT FROM AUTHOR]

The determination of viscosity of liquid Cr-Mn-Ni steel (16% Cr, 7% Mn) alloyed with 3-20% nickel is of interest in the present experimental investigation. The alloys are manufactured using a cold crucible induction levitation melting. The viscosity measurement is performed using a vibrating finger viscometer for high temperatures (≥1500 °C) and viscosities below 10 mPa s. The BN-ZrO2 vibrating finger is set in a driven harmonic oscillation in its resonance frequency of ca. 26 Hz. The constant peak-to-peak amplitude of the oscillator is controlled using a laser micrometer and a powered field coil. The viscosity of Fe-Cr-Mn-Ni alloys is slightly decreased from 3 to 6% nickel and from 6 to 9% nickel a slight increase of the isothermal viscosity is observed. Finally, the viscosity decreased significantly from 9 to 20% nickel content in the samples. The variation in the viscosity at high temperatures can be caused by a change in the primary solidification behavior, as shown in the phase diagram of the Cr-Mn-Ni steel. The temperature function of the viscosity of the high-alloyed steels is expressed using the Arrhenius function. A precise viscosity measurement is necessary for a mathematical modeling of the vacuum inert gas atomization of steel powder manufacturing. [ABSTRACT FROM AUTHOR]

By means of a simplified quenching and partitioning (Q&P) processing with quench temperature equal to room temperature, austenite fractions of 56, 43, and 24 vol% are stabilized in the microstructures of Q&P-processed Fe-Cr-C, Fe-Cr-C-Co, and Fe-Cr-C-N stainless steels, respectively. The mechanical stability of austenite is quantified by tensile tests at temperatures between 20 and 200 °C. In agreement with the Q&P concept, the stability of austenite is found to be highest for the steel with the highest martensite fraction. The carbon enrichment of austenite in a specimen of the Fe-Cr-C steel processed to have 82 vol% martensite is estimated by X-ray diffraction measurement of the austenite lattice parameter. The results indicate that only about 12% of the carbon contained in the martensite has partitioned into the austenite. The formation of tempering carbides is one of the mechanisms behind the significant deviation of the carbon enrichments from the full partitioning assumption. [ABSTRACT FROM AUTHOR]

Non-metallic inclusions can affect significantly the mechanical properties of metallic materials. Mainly for safety relevant components, it is important to reduce size and number of non-metallic inclusions. Recent research work is focused on the development of new reactive, active, and functionalized filters for the reduction of non-metallic inclusions. A detailed knowledge on the genesis of inclusions is essential to improve the entrapment capability. The paper is focused on the microstructure of inclusions formed in cast steel 42CrMo4 after the application of two filter variants. Both, inclusions on the filter surface as well as inclusions in the as-cast steel are investigated using scanning electron microscopy. Their chemical composition and their crystal structure are identified by combined EBSD and EDS measurements. The three-dimensional morphology of the inclusions is analyzed by deep etching technique as well. Finally, the clusters and agglomerates exhibit a quite complex microstructure. Thus, the majority of inclusion clusters consists of alumina, spinel, mullite, MnS, and TiO x. This agrees well to the scenario of the evolution of inclusions described in the literature. [ABSTRACT FROM AUTHOR]

In-situ Fe-TiC metal matrix composite (MMC) was successfully fabricated via Laser Powder Bed Fusion (L -PBF) using an in-house gas atomized Fe-TiC composite powder. The optimization campaign of printing parameters targeted the maximum density of printed cubic samples. The highest Archimedes density of 7.615 g cm−3 was achieved by laser power of 210 W, scan speed of 763 mm s−1, and hatch spacing of 80 µm corresponding to a volume energy density (VED) of 68.78 J mm−3 given the constant layer thickness of 50 µm. The relative density of the optimized sample was also measured by Computer Tomography (CT) scanning yielding a relative density of 99.85%. According to measured chemical composition and subsequent thermodynamic calculation, the TiC phase can be up to 7.2 vol%, and X-ray diffraction analysis (XRD) confirmed the presence of TiC phase in bcc-iron. Furthermore, Scanning Electron Microscopy (SEM) of sample cross-sections revealed well-dispersed submicron and nano TiC precipitates of two morphologies and size ranges – primary cubic particles (100–400 nm in size) and secondary plate-like particles (up to 300 nm length and below 50 nm width). No micro-cracks and contaminations were detected between the matrix and reinforcement. Electron Back Scattered Diffraction (EBSD) analysis of a cross-section parallel to build direction revealed extremely fine equiaxed grains with a mean size of 1.3 µm which suggests Columnar to Equiaxed Transition (CET). CET and grain refinement were most likely induced by the presence of TiC particles and rapid solidification within L -PBF. Finally, the micro-hardness tests were conducted to evaluate the reinforcement potential of TiC particles. The mean value of 357.0 ± 9.3 HV1 was obtained for the optimized sample which is superior to pure Fe fabricated via L -PBF and a similar MMC fabricated by Electron Beam Powder Bed Fusion (EB-PBF). Furthermore, the microstructure and hardness of the optimized sample was compared to the sample from optimization campaign with the highest coincident VED and relative density. Some micro-defects were observed in the optimized build and their morphologies and origins were discussed. • In-situ Fe- 7.2 vol% TiC metal matrix composite (MMC) was successfully fabricated via Laser Powder Bed Fusion (L-PBF). • In-house gas atomized Fe-TiC experimental composite powder was used for fabrication. • Computer Tomography (CT) scanning revealed a relative density of 99.85% for the sample with optimized parameters. • Scanning Electron Microscopy (SEM) of sample cross-sections revealed well-dispersed submicron and nano TiC precipitates. • TiC morphologies and size ranges – primary cubic submicron particles and secondary plate-like nano-particles. • Optimized sample demonstrated extremely fine equiaxed grains with a mean size of 1.3 µm. • The micro-hardness tests revealed 357.0±9.3 HV1 for the optimized sample. [ABSTRACT FROM AUTHOR]

The present work investigated the effect of V 2 O 3 in the range of 0 to 10.5 wt% on the thermophysical properties (viscosity, density, and surface tension) of CaO-SiO 2 -Al 2 O 3 -MgO-TiO 2 slags with the CaO/SiO 2 =1.3 and varied content of Al 2 O 3 and TiO 2. The obtained experimental results were then supported by thermodynamic calculation with FactSage 7.2. The results shown that, with the increase of the V 2 O 3 content, the viscosity of all studied slags decreased. Moreover, the addition of TiO 2 up to 10 wt% to the matrix slag led to a decrease in viscosity and the addition of Al 2 O 3 up to 20 wt% increased the viscosity without the presence of V 2 O 3. Thereby the behavior of critical temperature on all viscosity curves corresponded with the behavior of crystallization temperature of melilite. The increase in the content of V 2 O 3 to 10.5 wt% in all slags with and without additional TiO 2 or Al 2 O 3 resulted in an increase in density at temperatures of 1450–1650°C. The surface tension increased with increasing Al 2 O 3 content and decreased with increasing TiO 2 and V 2 O 3. [ABSTRACT FROM AUTHOR]

Cleaning filter systems for metal melt filtration combine reactive filtration by functionalized filter surfaces for chemical reaction with the steel melt and active (mechanical) filtration. In the present work, a combined cleaning filter system was applied to 42CrMo4 steel melt containing nonmetallic inclusions, which were generated artificially before filtration. The nonmetallic inclusions in the solidified steel were investigated by an automated scanning electron microscope (ASPEX), nanoindentation, atomic force microscopy (AFM), focused ion beam technique (FIB) and confocal laser scanning microscopy (CLSM). The combined filter system was found to reduce the amount of aluminum in the steel and to form novel multiphase inclusions. These multiphase inclusions consist of TiO 2-x and Al 2 O 3 in a low-melting spessartine matrix and were characterized by nanoindentation. Compared to pure Al 2 O 3 inclusions, the spessartine inclusions are softer and have a lower Young's modulus, fitting much better to the mechanical properties of the steel. The area below the indents was investigated by focused ion beam technique and transmission scanning electron microscopy revealing cracks and dislocations. Furthermore, the low-melting character of the spessartine matrix was proven by means of a confocal laser scanning microscope. Accordingly, the low-melting spessartine inclusions appear as liquid inclusions during steel melt processing and could contribute to clogging prevention in continuous steel casting. • Combined steel melt filtration system caused formation of multiphase inclusions. • Multiphase inclusions entrapped TiO2-x and Al2O3 in a matrix of soft spessartine. • During nanoindentation of Al2O3, pop-in events marked elastic-plastic transition. • Analysis of EBSD data by MTEX suggest activation of pyramidal slip system in Al2O3. • Beneath the indents, plastic zone based on dislocations was observed by t-SEM. [ABSTRACT FROM AUTHOR]

This paper presents a systematic study of quenching and partitioning (Q&P) processing of a (C + N)-containing austenitic stainless steel with a special focus laid on the influence of partitioning conditions on the mechanical properties and its comparison with C-containing Q&P-treated stainless steels. Similar to C-containing stainless steels, martensite phase in the studied steel exhibited pre-precipitation phenomena such as interstitial segregation to defects below 250 °C and precipitation reactions such as the formation of paraequilibrium M 3 C carbides (M representing Fe and substitutional elements) above 300 °C. The interstitial partitioning between martensite and austenite and the dependence of mechanical properties on the partitioning conditions resembled those of C-containing stainless steels. With increasing partitioning temperature, interstitial enrichment in the austenite and ductility were enhanced while tensile strength decreased. Similar observations were made upon prolonged partitioning at 250 °C. In contrast, the ductility of steels partitioned at 350 °C and 450 °C barely changed with partitioning time. For partitioning at 450 °C, this was because most of the interstitial partitioning at 450 °C took place within the first 3 min of partitioning. For partitioning at 350 °C, the interstitial enrichment of fine austenite regions was completed rapidly as well and the later interstitial partitioning into coarse austenitic regions gave rise to little increase in austenite stability due to their large size. The optimal product of ultimate tensile strength and total elongation, 47 GPa%, was obtained after partitioning at 450 °C for 3 min. The sufficiency of a short partitioning to obtain superior mechanical properties is of great practical significance in the context of growing global concerns about energy demand and climate change. • Quenching and partitioning of a (C + N)-containing austenitic stainless steel. • Reactions competing with interstitial partitioning. • Mechanical properties insensible to partitioning time at specific temperatures provide possibilities for energy efficiency. • Presence of isothermal martensite upon subzero quenching. • Comparison with quenching and partitioning of C-containing stainless steels. [ABSTRACT FROM AUTHOR]

• Copper selenide was formed and located on the oxides after the addition of selenium into the liquid Fe-Cu alloy. • Copper selenide was massively detected in the slag along with the alumina or (Mg, Fe)Al 2 O 4 -spinel. • The detected copper selenide indicate that selenium may be considered as a sufficient approach for the decopperization. Selenium was added into the molten Fe-Cu alloy at 1600 °C to test its decopperization possibility. After the addition of selenium into the liquid Fe-Cu alloy, copper selenide was found to deposit on the particle with a complex composition that located on the solidified alloy sample. Furthermore, a secondary metallurgical ladle slag with a high content of alumina was added into the liquid Fe-Cu alloy after the addition of selenium. Thereby the decopperization efficiency was found to be enhanced by the addition of slag. The copper selenide was massively observed in the slag along with the oxides (alumina or (Mg, Fe)Al 2 O 4 -spinel). The formation of the spinel was predicted by the FactSage software. [ABSTRACT FROM AUTHOR]