International Journal of iron and steel society of Iran
Volume:20 Issue: 2, Summer and Autumn 2023

In this research, the properties and microstructure of direct bonded dolomite refractory (having) Iron oxide (Fe2O3) and Chrome oxide (Cr2O3) nanoparticles have been investigated. For this reason 0, 0.5, 1, 1.5, 2, 2.5 and 3 wt. % of Fe2O3 and Cr2O3 nanoparticles have been added to the composition. After forming the samples as cylinders (50*50 mm2), they were fired in an electric furnace at 1650 °C for 3 hr. The measured parameters were bulk density, apparent porosity, hydration resistance and cold crushing strength. Also, microstructural investigation and phase’s analysis of the selected samples was performed by scanning electron microscopy (SEM/EDX) and X-ray diffraction (XRD) devices; respectively. Results showed that the use of Cr2O3 nanoparticles lead to formation of CaCr2O4 and MgCr2O4 phases, which improved the sintering process of the samples thorough the solid state sintering mechanism. Also, the use of Fe2O3 nanoparticles leads to creating CaO.Fe2O3 (CF) and 2CaO.Fe2O3 (C2F) phases which improved the sintering process of the specimen thorough the liquid phase sintering mechanism. Also, it showed that Cr2O3 nanoparticles additive has a greater effect on improving the properties of direct bonded dolomite specimens compared to Fe2O3 nanoparticles additive.

In this study, the effect of delta ferrite formation and segregation of alloying elements on the mechanism of edge cracking on the surface of AISI304L stainless steel during hot rolling in Iran Alloy Steel Company was evaluated. For this purpose, scanning electron microscopy (SEM) with two detectors, SE and BSE, and EDX analysis were used to examine the areas around the crack. The results was shown that the tendency to create edge cracks during hot rolling increases with enhancement delta ferrite content and the mechanism of crack growth is along the delta ferrite and the delta ferrite/ austenite interface. SEM studies of the crack-containing specimens in showed the number of micro-cracks in the areas around the main crack and the presence of worm-shaped delta ferrites and delta ferrite islands in the austenitic matrix. In addition, the segregation of the copper element also plays an important role in creating cracks in the surface of AISI304L stainless steel ingots during hot rolling.

This research used response surface methodology with a central composite design to optimize the metallization degree of the Midrex-type Gohar plant of Golgohar Iron and Steel Development Company, Sirjan City. For this purpose, the effect of furnace bed temperature, bustle gas temperature, process gas CO2, reformed gas CO 2, and process gas flow/ton was investigated on the metallization degree of the sponge iron. The statistical analysis showed that the furnace bed temperature is the most effective parameter for the quality of the sponge iron in Midrex, and the most significant interaction was observed between the furnace bed temperature and the reformed gas CO2. The coefficient of determination and the standard error for the model were obtained at 0.9901 and less than 5%, respectively, which indicates the model was optimal. According to the optimization results, the best metallization degree of 93 was obtained in the furnace bed temperature of 727 °C, process gas CO 2 of 17.29%, bustle gas temperature of 859.55 °C, reformed gas CO2 of 2.98%, and process gas flow/ton of 1146 Nm3/ton.

Alloying is a technique that has long been used to provide desirable properties in materials. It mainly involves the addition of relatively small amounts of secondary elements to a primary element. Recently, a new alloying strategy that involves the combination of multiple principal elements in high concentrations to create new materials called high-entropy alloys has been investigated by several researchers. In this paper, the thermodynamic calculations and phase formation rules for the formation of FeCoCrMnNi high entropy alloy are discussed. The FeCoCrMnNi and FeCoCrMnNiC 0.2, high entropy alloys were cast using a vacuum arc melting furnace. It was shown that both of the high entropy alloys formed a single FCC solid solution phase without any other impurities or phases. The whole pattern Rietveld refinement analysis showed that the addition of carbon to the FeCoCrMnNi high entropy alloy decreased the crystallite size. Moreover, the Tafel corrosion test results indicated that the corrosion resistance of the FeCoCrMnNi high entropy alloy increased 185 times with the addition of carbon.

316 stainless steel is one of the alloys commonly used for surgical instruments. These tools, when in contact with bacteria, are highly prone to contamination. By applying coatings with antibacterial properties, this problem can be significantly mitigated. The purpose of this research is to design a novel Zr-based alloy with glass structure , possessing antibacterial properties, and apply it to 316 stainless steel. First,, an alloy with the chemical composition Zr30Cu20Al10Ag10Cr10Si10B10 was designed and produced using a SPS system. Next, thin layers of the alloy were deposited on 316 steel samples using a Magnetron Sputtering machine. The GIXRD tests indicated success in obtaining a completely amorphous structure. The antibacterial behavior of the created coating against two bacteria, Escherichia coli and Staphylococcus aureus, was investigated. The results showed that the coating, due to the presence of Cu and Ag in the alloy, exhibited high antibacterial properties against these bacteria. Additionally, the application of the new coating can play an important role in the adhesion of various cancer cells to surgical tools made from 316 stainless steel, due to the reduction of substrate roughness by approximately 50%.Tests showed that the application of the coating reduced the free energy of the surface and thus increased the hydrophobicity of the surface, transforming the surface of 316 stainless steel from hydrophilic to hydrophobic. Furthermore, the amorphous structure of the coating enhanced the corrosion resistance of the 316 steel in 3.5% NaCl solution. Therefore, applying the newly designed coating to biomedical steel tools is suggested.

Due to internationally agreed commitments to reduce production and CO2 emissions in various industries, including steel and sponge iron production through various direct reduction processes such as Midrex, these processes are now being used and developed worldwide more than ever. However, the technological complexity in this area, resulting from a multitude of control parameters and the intricate cause-and-effect relationships between these parameters, means that different plants around the world produce under slightly different quantitative and qualitative conditions.This article aims to educate stakeholders that it is possible to produce sponge iron with improved quantity and quality by highlighting the successful results of leading direct reduction plants in this context. It then explains how this goal can be achieved by relying on indigenous and certified technical knowledge such as KIPEX, which is able to implement automation levels 1 and 2. The introduction of KIPEX technology in sponge iron production has led to significant improvements. The production rate increased from 115 to 125 tons per hour, with metallization increasing from 92.088% to 93.77%. The carbon content fell from 1.3% to 1.28%, and the process gas throughput was reduced from 109,500 Nm3/hour to 107,000 Nm3/hour. These improvements mean higher productivity, quality, and efficiency in the production of sponge iron.

In this research, Al2O3 powders were successfully synthesized by employing different initial materials of aluminum nitrate and aluminum acetate through the facile solution combustion approach. Al2O3 based insulation materials possess many essential applications in steel manufacturing industries regarding their considerable heat-resistance characteristics. To study the crystal structure, microstructure, and surface chemistry of the synthesized oxides, X-ray diffraction (XRD), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) were employed. It was found that the use of aluminum acetate facilitates the synthesis of semi-crystalline Al2O3 in the synthesis condition, while regardless of the used initial materials, calcination treatment at 1000 °C gives rise to the improvement of crystallinity. Additionally, the SEM observations clarified that through the employment of aluminum acetate, very fine particles with the approximate size of 1 μm were produced. The FTIR characterizations revealed that the peaks at 570 and 790 cm-1 originate from Al-O bonds in the octahedral and tetrahedral coordination and confirmed the synthesis of Al2O3. In short, to produce Al2O3 powders, the utilization of combustion by urea fuel and aluminum acetate brings appropriate characterizations.

Gas metal arc welding (GMAW) based wire-arc additive manufacturing (WAAM) is a promising manufacturing method widely used in various industries. In this study, for the first time, a new type of combined electrode wire with multi-element composition has been designed and developed for arc additive manufacturing of a composite alloy Fe rich-Al-Cu-Ni alloy. GMAW-based WAAM technique technology composed of 4 filaments and 4 elements has the advantages of high deposition efficiency, self-rotation of welding arc, and energy-saving capability. Thin composite alloy walls were fabricated under pure CO2 gas using GMAWbased WAAM technique technology. To investigate the effect of the parameters introduced by the gas metal arc welding process based on wire arc additive manufacturing, the produced components of the sample layer by layer with different parameters after production are characterized by scanning electron microscope morphologies, X-ray diffraction Microstructural observations of the developed combined electrode reveal (i) BCC and FCC phases, (ii) Good bonding between layers and (iii) defect-free microstructure. Therefore, an experimental design using the Taguchi method was used to determine the parameters affecting the studied properties, including yield strength (YS) and elongation (E). The developed combined electrode alloy exhibits high compression strength (~294 GPa) coupled with high elongation (~0.22%) values (possess both strength and ductility). It has been identified that by varying the heat input via torch travel speed, the microstructure and mechanical properties of the combined electrode can be controlled. Therefore, optimizing GMAW process parameters to produce effective products is of great importance. The experimental results show that voltage and wire speed are the dominant variables that affect the values of YS and E at the test surface. In addition, the contribution of each factor to YS and E was determined. Which can be effectively Corrected with this method.

Recycling approaches are emerging as intriguing and sustainable topics for environmental safety. Machining chips offer the possibility of reuse in more sustainable and cost-effective production pathways, such as producing powder from milled scraps for additive manufacturing. Recycling practical materials like steel with low processing costs, combining economic and engineering advantages, presents a vital demand for designing more sustainable and reliable components for the aerospace and automotive industries. The present study utilizes CK45 steel for recycling and, by generating machining scraps in a closed-loop cycle, achieves a unique combination of material properties. The produced composites containing 0.1% and 0.2% weight percentages of reduced graphene oxide are fabricated using spark plasma sintering. They undergo hardness, compression, wear, and corrosion tests, as well as scanning electron microscopy (SEM) and XRD analysis for comprehensive characterization. Hardness and wear tests reveal that these waste materials possess suitable hardness for use in parts manufacturing for industries in which the Hardness and wear resistance are important factors in service conditions. The results of hardness and wear investigations indicate an increase in hardness by 140 units and a weight reduction of 18 mg in the produced samples compared to the cast sample.

Mill optimization has many economic benefits. Semi autogenous grinding mills are complex multi-input and multi-output systems that are difficult to optimize. The purpose of this study is to examine the functions of the wear of lifters, power draw and product size distribution. The design variables are mill speed, ball filling, slurry concentration and slurry filling. To achieve this aim, a pilot mill was carried out. The experimental results used to create training cases for the artificial neural network and then the optimization of the design variables is conducted by multi-objective genetic algorithm. Level diagrams are then used to select the best solution from the Pareto front. Finally, the response surface methodology has been used to study the interaction between the design parameters. The results showed that the best grinding occurs at 70-80% of the critical speed and ball filling of 15-20%. Optimized grinding was observed when the slurry volume was 1-1.5 times of the ball bed voidage volume and the slurry concentration was 60-70%. Additionally, variables with the largest effect on the process are mill speed and ball filling.