Journal of Mining and Metallurgy, Section B: Metallurgy

An investigation of plastic deformation behaviour of Nb-V microalloyed steel produced by powder metallurgy

Süleyman Gündüz — 2024-12-30

In this study, Nb-V microalloyed steel was produced and sintered at 1150 °C for 1 h followed by cooling in furnace. While one of the sintered samples was used in the sintered condition, the other one was cooled in air after homogenisation heat treatment at 1150 °C for 1 hour. The remaining samples were deformed at 20%, 40% and 60% in the temperature range 1150-930 °C and then cooled in air. Microstructure and precipitates formation of samples were investigated by optic microscope, scanning electron microscope and energy dispersive spectroscopy analyses. It was observed that samples showed smaller grain size, but higher volume fractions of ferrite under homogenised and 20%, 40% or 60% deformed conditions. This indicated that grain refinement and ferrite formation is accelerated with the deformation which affect the nucleation rate of ferrite. Also, the yield strength, hardness and density increased by the increase in deformation rate.

Effect of rotation rates on dissolution behavior of lime in CaO-FetO-SiO2-MgO system

Cao Jia — 2024-12-30

For the converter steelmaking process, incompletely dissolved lime will exist in steel slag in the form of f-CaO, which reduces utilization rate of metallurgical slag and causes the waste of resources. It is extremely important to reduce the production of f-CaO in steel slag and promote the quick and sufficient dissolution of lime. This paper is based on the early and middle stages of the converter slag-forming route based on CaO component. The dissolution rate of lime in four different slags was measured by rotating rod method. The evolution behavior of the lime-slag interface and the change behavior of the lime dissolution rate were studied by X-ray diffractometer and electron probe micro-analyzer. The experimental results show that CaO-FeO solid solution and (Ca, Mg, Fe) olivine are formed when lime reacts with molten slag at 1400℃. When the FeO content decreases, CaO will react with the calcium-magnesia-silica to form a high melting point and dense 2CaO·SiO₂ layer. In addition, at different rotation rates, a 3CaO·SiO₂ phase layer is formed between CaO-FeO solid solution layer and C₂S layer. When rotation rate increases, the dissolution rate of lime also increases and mass transfer coefficient reaches the maximum when rotation rate is 180 rpm. The maximum values are respectively 20.54×10^-6 m/s, 7.86×10^-6 m/s, 9.38×10^-6 m/s, 5.53×10^-6 m/s.

Selection of pulverized coal fuel components for blast furnaces based on the study of physico-chemical processes during their heating

Sergei Fedorov — 2024-12-30

There is a global tendency to use technologies related to saving energy costs per unit of production in blast furnace production. This is due to the use of pulverized coal fuel (PCF) instead of part of the coke. The selection of components of the PCF charge from a wide range of carbon-containing materials to expand the raw material base and minimize cost is an important task. One of these materials is peat. The purpose of this work is to develop a methodology for selecting pulverized coal fuel components based on their comprehensive study on the example of milling peat. Industrial experiments were carried out at an operating metallurgical plant. The particle size of PCF is no more than 70-100 μm. Thermal destruction of peat in an inert atmosphere accounts for 59% of the mass loss. The maximum destruction rate is 2.69%/min versus 2.0%/min for long–flame coal. The release of volatile components begins at 425°C for lean coal, 300°C for brown coal and 220°C for peat. The destruction of coal also leads to an increase in the specific surface area. It grows from 2.04 to 161.3 m²/g for brown coal. Combustion accounts for about 27% of the total loss of peat mass, for long-flame coal this value is twice as high. The total thermal effect for coal is in the range from 15510 to 17751 kJ/kg, for peat from 12816 to 14148 kJ/kg. Pulverized coal fuel produced during the pilot period was blown into an industrial blast furnace. The equipment of the PCF feed path, the poppet mill worked stably without changing the operating parameters. There were no deviations in the operation of the blast furnace. Due to the introduction of peat, the consumption of lean coal was reduced. The consumption of PCF and natural gas has practically not changed.

Characterizations and boron diffusion modelling on the AISI H13 steel

Mourad Keddam — 2024-12-30

A kinetic approach accounting for the linearity of boron profiles through the boronized layer on AISI H13 steel was developed. It aims to track the temporal evolution of the thicknesses of FeB and (FeB + Fe₂B) layers by considering new expressions for the mass balance equation at each growth front. These surface layers were generated by pack-boronizing AISI H13 steel in the temperature range of 1123 to 1273 K for durations ranging from 2 to 8 hours.. Finally, this linear model has been validated for two other sets of processing parameters (1323 K for 4.5 and 8.5 h). Iso-thickness diagrams were also proposed to optimize the thicknesses of the layers for targeted industrial usage.

Effects of hot rolling on microstructures, wear and corrosion resistance of Mo-Ni-W P/M alloyed steels

RAJAB ELKILANI — 2024-12-30

This study analyzes how hot rolling changes the Fe-0.55C-3Mo-10Ni-0.5W alloy steel's microstructure, tensile strength, wear, and corrosion behaviors. Metal powders were pressed at 750 MPa pressure, and the cold-pressed samples were sintered at 5°C/min up to 1400°C for two hours in a mixed-gas environment of 90% nitrogen and 10% hydrogen. Following that, the generated steels underwent hot rolling at 40% and 80% deformation rates. The microstructures demonstrate that MoC(N), WC(N), and MoWC(N) were created and that the steels had finer microstructures and better mechanical characteristics as the deformation rate increased. As the degree of distortion increased, the wear reduced. Furthermore, the hot rolling method improved corrosion resistance, as shown by the Tafel curve analysis. The greatest factor supporting corrosion resistance was the increase in density value throughout the rolling process.

Deformation behavior of typical inclusions in GCr15 during hot rolling process

Jianli Li — 2024-12-30

Non-metallic inclusions significantly impact the lifespan of bearing steel. Investigating the deformation behavior of these inclusions during the rolling process is crucial for controlling their shape and size in production. This study focuses on GCr15 bearing steel, a representative grade of bearing steel, and utilizes the finite element software ABAQUS to simulate the deformation of Al₂O₃ inclusions, MnS inclusions, and Al₂O₃-MnS composite inclusions after hot rolling of GCr15 steel. The findings indicate that when the size of inclusions is within 10 µm, their type and shape have a more significant impact than variations in size. Among them, Al₂O₃-MnS composite inclusions exhibit the least harm to the steel matrix. The stress concentration of Al₂O₃ inclusions will appear on the MnS cladding layer, which can slow down the occurrence of cracks. Additionally, the aspect ratio of MnS inclusions decreases after rolling, diminishing its influence on the steel matrix's anisotropy. Simultaneously, composite inclusions can harmonize the deformation capabilities of the inclusions and the steel matrix, thereby minimizing the likelihood of void formation. Consequently, in the smelting process, it is beneficial to modify inclusions into regular circular shapes and form composite Al₂O₃-MnS inclusions to mitigate their detrimental effects on the steel matrix.

Separation of Co(II), Mn(II) and Ni(II) from the sulfuric acid leaching solution of lithium-ion battery by solvent extraction

Manseung Lee — 2024-12-30

Lithium-ion batteries(LIBs) contain valuable metals such as cobalt, lithium, manganese, and nickel. Therefore, recycling of spent LIBs is important to meet the demand for the above-mentioned metals. In combined process for the treatment of spent LIBs, smelting reduction of LIBs results in metallic alloys containing cobalt, manganese, nickel, and a small amount of other metals. These metallic alloys can be dissolved using sulfuric acid solutions containing oxidizing agents. In this work, solvent extraction experiments were done to separate Co(II), Mn(II), and Ni(II) from synthetic sulfate solution, the composition of which was similar to the leaching solutions of spent LIBs. The concentrations of Co(II), Mn(II) and Ni(II) in the sulfate solutions were 2, 0.3, and 8 g/L, respectively. First, it was possible to completely separate Mn(II) from Co(II) and Ni(II) by selective extraction using two stages of counter-current extraction with 10% saponified 0.3 M D2EHPA. Then, pure MnSO₄ solution was recovered by stripping the loaded D2EHPA with 0.05 M H₂SO₄ solution. From the Mn(II) free raffinate, Co(II) was completely separated over Ni(II) by two stages of counter-current extraction with 15% saponified 0.3 M Cyanex 272. The purity of Ni(II) in the raffinate was higher than 99.9% and pure CoSO₄ solution was recovered by stripping the loaded Cyanex 272 with 0.05 M H₂SO₄ solution. A process on the basis of solvent extraction with commercial organophosphorus extractants was proposed to recover pure CoSO₄, MnSO_4, and NiSO₄ solutions from the sulfuric acid leaching solutions of spent LIBs.

Prediction model of blast furnace molten iron temperature and molten iron silicon content based on improved arithmetic optimization twin support vector machine for regression

ChunYang Shi — 2024-12-30

The temperature and silicon content of blast furnace molten iron are directly related to its quality. Therefore, establishing an effective prediction model for these parameters is crucial. To address these issues, an Improved Arithmetic Optimization Twin Support Vector Machine for Regression (LAOA-TSVR) model was developed to predict the temperature and silicon content of blast furnace molten iron. Initially, SPSS was used to perform a correlation analysis and identify the main influencing factors. Secondly, to verify the model's predictive performance, it was compared with three commonly used prediction models: Back Propagation Neural Network (BP), Support Vector Regression (SVR), and Twin Support Vector Machine for Regression (TSVR). Preliminary results indicate that the prediction accuracy of the LAOA-TSVR model is significantly higher than that of the other models. Finally, the model was applied to the actual production process of an iron mill for a total of 200 furnaces. The results show that the hit rates of molten iron temperature and silicon content within the error ranges of ±5% and ±0.5%, respectively, are 92.12% and 92.53%, with a corresponding double-hit rate of 85.32%. The model effectively meets the production requirements of an iron mill and provides valuable guidance for the blast furnace production process.

Development of an efficient solar concentrator and utilization in copper extraction from copper minerals

Alejandro Valdivieso — 2024-12-30

A novel and cost-effective solar concentrator has been developed to enhance efficient copper extraction. Based on the criteria for a stationary compound parabolic concentrator, the reflector geometry incorporates a half-spherical curve and a strength line. This design significantly improves the concentrator's ability to capture more marginal rays compared to widely used commercial solar concentrators. In this study, a newly configured solar concentrator was constructed with aluminum sheet and tested in San Luis Potosi, Mexico, with a comprehensive performance analysis. The investigation revealed an optical efficiency of 0.73 and a maximum thermal efficiency of 68%. Experimental results demonstrated that the solar collector could absorb solar radiation throughout the year without the need for a tracking system. It efficiently facilitated the copper sulfide ore leaching process at a medium temperature of approximately 70 °C. Capital cost analysis indicated an exceptionally low unit manufacturing cost of only $125 USD /m². The study further proposes that the implementation of this solar collector could potentially double the copper recovery rate and triple the annual increase in copper cement without contributing to CO₂ emissions. Additionally, the feasibility of deploying this new concentrator on an industrial scale was thoroughly evaluated to provide a substantial support for advancing cleaner copper production technology through further innovation.

Enhancing Microstructure, Grain Refinement, and Wear Properties of Cast A356-TiB2 Composite through Improved Sequence of ECAP and Heat Treatment Processes

Anasyida Seman — 2024-12-30

This study aimed to enhance the grain structure, hardness, and wear resistance of A356-1.5TiB₂ composite through a combination of manufacturing processes. Initially, the composite was produced using casting, followed by equal channel angular pressing (ECAP) and heat treatments in various sequences. The heat treatment process involved a solution heat treatment (540ºC, 4 hours), followed by rapid quenching in water (90ºC). The ECAP process was carried out via the BA route, involving four passes at room temperature. After ECAP, an aging process was conducted at 155ºC for 3 hours. The post-application of ECAP and heat treatments had a positive impact on the distribution of TiB₂ and TiAl₃ particles, aluminum matrix grain refinement, and improved hardness and wear properties of the composite. The composite underwent both ECAP and heat treatment exhibited finer grain structure and higher hardness. The sequence of post-applications of ECAP and heat treatments also affected the grain structure, hardness, and wear resistance of the composite. The composite that underwent solution treatment followed by aging treatment and then ECAP demonstrated the most refined structure and highest hardness. These findings demonstrate that a carefully designed manufacturing process can significantly enhance the mechanical properties of A356-1.5TiB₂ composite.

Influence of tool steel alloying elements Mo and Ni on the formation of the interaction layer between tool steels and molten aluminium alloys

Maja Vončina — 2024-12-30

The dissolution of tool steels in molten aluminium alloys is affected by the presence of alloying elements in both the molten aluminium and the tool steel. The present work was carried out to predict the effect of tool steel alloying elements, mostly Ni and Mo, on the interaction layer formed between tool steel and molten aluminium alloy.

The interaction layer between the investigated tool steels Dievar or RavnexHD and Al99.9 and Al99.7 aluminium alloy consists of an intermetallic and a composite layer. The interaction layer between the investigated tool steels and the AlSi12 aluminium alloy consists of three different interaction layers. The better solubility resistance in various molten aluminium alloys shows hot-work tool steel RavnexHD. The main alloying element in the tool steels investigated, that influence on the dissolution of tools teel in molten aluminium is Ni, which is present in higher amounts in RavnexHD. Ni incorporate in the matrix, inhibits the diffusion of iron and aluminium through the matrix. Mo in Dievar tool steel forms carbides, allowing easier diffusion of these elements through the Fe-matrix.

Analysis on premature cracking causes of ASTM A213-T12 superheater tube

Jiaoguo Chen — 2024-12-30

The failure behavior of superheater tube prepared by ASTM A213-T12 steel was studied. The microstructure and hardness at different positions of the tube, and the element distribution at the crack position, as well as the morphology and phase composition of the corrosion layer were analyzed using optical microscopy (OM), microhardness tester, scanning electron microscopy (SEM), and X-ray diffractometer (XRD). The results indicate that the pearlite at the failure position undergoes spheroidization and the hardness is significantly reduced compared to the normal position. Failure is closely related to corrosion and creep. On the one hand, there is sulfur corrosion and oxidation corrosion on the outer layer of the superheater tube, which seriously reduces the thickness of the tube. On the other hand, the creep resistance of the tube is significantly reduced due to thinning. There are numerous creep voids in the microstructure at the failure site. Meanwhile, oxygen can diffuse into the voids to promote oxidation corrosion.

From From the alloy design to the microstructural and mechanical properties of medium manganese steels of the third generation of advanced high strength steels

Hamza ESSOUSSI — 2024-12-30

In the automotive industry, there is significant interest in developing the third generation of advanced high strength steels (3GAHSSs), particularly the so-called medium Mn steels, which have gained more focus due to their promising properties and relatively inexpensive manufacturing costs. As a result, the purpose of this work is to discuss the original and significant findings in the development of this grade of steel, with a particular emphasis on the link between microstructure, processing, and mechanical characteristics.