Materials

Editorial

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3 pages, 169 KiB

Open AccessEditorial

Metallurgical Process Simulation and Optimization

by Jiangshan Zhang, Yuhong Liu and Qing Liu

Materials 2022, 15(23), 8421; https://doi.org/10.3390/ma15238421 - 26 Nov 2022

Cited by 1 | Viewed by 1138

Abstract

Metallurgy involves the art and science of extracting metals from their ores and modifying them for use [...] Full article

(This article belongs to the Special Issue Metallurgical Process Simulation and Optimization)

Research

Jump to: Editorial

13 pages, 6239 KiB

Open AccessArticle

New Insights into the Mechanism of Nucleation of ZrO₂ Inclusions at High Temperature

by Yutang Li, Linzhu Wang, Chaoyi Chen, Shufeng Yang and Xiang Li

Materials 2022, 15(22), 7960; https://doi.org/10.3390/ma15227960 - 10 Nov 2022

Cited by 3 | Viewed by 1183

Abstract

It is difficult to observe the nucleation mechanism of inclusions in real-time. In this study, the nucleation process of zirconium oxide inclusions was systematically studied by classical nucleation theory and first principles. Zr deoxidized steel with 100 ppm Zr addition was processed into [...] Read more.

It is difficult to observe the nucleation mechanism of inclusions in real-time. In this study, the nucleation process of zirconium oxide inclusions was systematically studied by classical nucleation theory and first principles. Zr deoxidized steel with 100 ppm Zr addition was processed into metallographic samples for scanning electron microscopy energy-dispersive spectroscopy observation. The electrolytic sample was analyzed by micro X-ray diffraction and transmission electron microscopy, and the zirconium oxide in the sample was determined to be ZrO₂. The nucleation rate and radius of the ZrO₂ inclusions were calculated by classical nucleation theory, and they were compared with the experimental values. There was a considerable difference between the experimental and theoretical values of the nucleation rate. The effect of the nucleation size was analyzed by first-principles calculation, and the thermodynamic properties of ZrO₂ clusters and nanoparticles were analyzed by constructing (ZrO₂)_n (n = 1–6) clusters. The thermodynamic properties of ZrO₂ calculated by first principles were consistent with the values in the literature. Based on two-step nucleation theory, the nucleation pathway of ZrO₂ is as follows: Zr_atom + O_atom → (ZrO₂)_n → (ZrO₂)₂ → core (ZrO₂ particle)–shell ((ZrO₂)₂ cluster) nanoparticle → (ZrO₂)_bulk. Full article

(This article belongs to the Special Issue Metallurgical Process Simulation and Optimization)

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14 pages, 3808 KiB

Open AccessArticle

Unveiling the Effect of CaF₂ on the Microstructure and Transport Properties of Phosphosilicate Systems

by Yizhe Du, Zhidan Huang, Mujun Long, Huamei Duan and Dengfu Chen

Materials 2022, 15(22), 7916; https://doi.org/10.3390/ma15227916 - 09 Nov 2022

Cited by 3 | Viewed by 1076

Abstract

As an effective flux, CaF₂ is beneficial in improving the fluidity of slag in the steel-making process, which is crucial for dephosphorization. To reveal the existence form and functional mechanism of CaF₂ in phosphosilicate systems, the microstructures and transport properties of [...] Read more.

As an effective flux, CaF₂ is beneficial in improving the fluidity of slag in the steel-making process, which is crucial for dephosphorization. To reveal the existence form and functional mechanism of CaF₂ in phosphosilicate systems, the microstructures and transport properties of CaO-SiO₂-CaF₂-P₂O₅ quaternary slag systems are investigated by molecular dynamics simulations (MD) combined with experiments. The results demonstrate that the Si-O coordination number does not vary significantly with the increasing CaF₂ content, but the P-O coordination number dramatically decreases. CaF₂ has a minor effect on the single [SiO₄] but makes the structure of the silicate system simple. On the contrary, F⁻ ions could reduce the stability of P-O bonds and promoted the transformation of [PO₄] to [PO₃F], which is beneficial for making the P element-enriched phosphate network structure more aggregated. However, the introduction of CaF₂ does not alter the tetrahedral character of the original fundamental structural unit. In addition, the results of the investigation of the transport properties show that the self-diffusion coefficients of each ion are positively correlated with CaF₂ content and arranged in the order of F⁻ > Ca²⁺ > O²⁻ ≈ P⁵⁺ > Si⁴⁺. Due to CaF₂ reducing the degree of polymerization of the whole melts, the viscosity decreases from 0.39 to 0.13 Pa·s as the CaF₂ content increases from 0% to 20%. Moreover, the viscosity of the melt shows an excellent linear dependence on the structural parameters. Full article

(This article belongs to the Special Issue Metallurgical Process Simulation and Optimization)

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14 pages, 3408 KiB

Open AccessArticle

Effect of Preheating Temperature on Thermal–Mechanical Properties of Dry Vibrating MgO-Based Material Lining in the Tundish

by Xiaodong Deng, Jianli Li and Xiao Xie

Materials 2022, 15(21), 7699; https://doi.org/10.3390/ma15217699 - 02 Nov 2022

Cited by 5 | Viewed by 1182

Abstract

For the collapse of the working layer of dry vibrating material during preheating, the four-strand tundish of a steel plant was taken as a prototype for numerical simulation. The software ANSYS was used to calculate the temperature field and stress and strain field [...] Read more.

For the collapse of the working layer of dry vibrating material during preheating, the four-strand tundish of a steel plant was taken as a prototype for numerical simulation. The software ANSYS was used to calculate the temperature field and stress and strain field on the working layer under three preheating stages through the indirect coupling method. The results show that during the preheating process, the temperature field distribution on the hot surface of the working layer gradually develops toward uniformity with the increase in preheating temperature. However, the temperature gradient between the cold and hot surfaces increases subsequently, and the highest temperature between the cold and hot surfaces reaches 145.31 °C in the big fire stage. The stress on the top of the working layer is much larger than in other areas, and the maximum tensile stress on the top reaches 39.06 MPa in the third stage of preheating. Therefore, the damage to the working layer starts from the top of the tundish. In addition, the strain of the area near the sidewall burner nozzle in the casting area is much larger than that in the middle burner area with the increase in preheating temperature. Thus, the working layer near the sidewall burner nozzle is more prone to damage and collapse compared with the middle burner nozzle. Full article

(This article belongs to the Special Issue Metallurgical Process Simulation and Optimization)

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24 pages, 6848 KiB

Open AccessArticle

Simulation of Inclusion Particle Motion Behavior under Interfacial Tension in Continuous Casting Mold

by Md Irfanul Haque Siddiqui, Ayidh Albaqami, Latif Arifudin, Khalid Alluhydan and Ibrahim Abdullah Alnaser

Materials 2022, 15(21), 7458; https://doi.org/10.3390/ma15217458 - 24 Oct 2022

Cited by 4 | Viewed by 1466

Abstract

Inclusions entrapped by the solidifying front during continuous casting adversely affect the properties of the final steel products. In this study, we investigated the effect of the interfacial tension due to surfactant concentration, particularly sulfur, on alumina inclusion motion behavior during molten steel [...] Read more.

Inclusions entrapped by the solidifying front during continuous casting adversely affect the properties of the final steel products. In this study, we investigated the effect of the interfacial tension due to surfactant concentration, particularly sulfur, on alumina inclusion motion behavior during molten steel solidification in a continuous casting mold. A two-dimensional numerical model was developed in Ansys Fluent software to simulate the inclusion motion in a continuous casting mold. Further, the impacts of different values of the alumina inclusion diameter, sulfur concentration, and melt temperature were studied to understand the inclusion motion behavior. The inclusion diameter affected the inclusion distribution throughout the domain. The alumina inclusion entrapment percentage varied in the case of sulfur mixing (using an empirical relationship for modeling). It was found that the removal percentage varied according to the sulfur concentration. The addition of sulfur at concentrations from 10 ppm to 70 ppm resulted in a 4% increase in the removal of alumina inclusions (trapped in the solidifying shell), except for the 100-ppm case. Smaller-sized inclusion particles had a 25% higher chance of entrapment at the top level of the mold. Under the effect of a higher surface tension gradient between inclusions and the melt, the predicted findings show that inclusions were vulnerable to engulfment by the solidification front. Full article

(This article belongs to the Special Issue Metallurgical Process Simulation and Optimization)

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19 pages, 7245 KiB

Open AccessArticle

Characterization of Hot Deformation of near Alpha Titanium Alloy Prepared by TiH₂-Based Powder Metallurgy

by Rongxun Piao, Wenjin Zhu, Lan Ma, Peng Zhao and Biao Hu

Materials 2022, 15(17), 5932; https://doi.org/10.3390/ma15175932 - 27 Aug 2022

Cited by 3 | Viewed by 1248

Abstract

TiH₂-basd powder metallurgy (PM) is one of the effective ways to prepared high temperature titanium alloy. To study the thermomechanical behavior of near-α titanium alloy and proper design of hot forming, isothermal compression test of TiH₂-based PM near-α type [...] Read more.

TiH₂-basd powder metallurgy (PM) is one of the effective ways to prepared high temperature titanium alloy. To study the thermomechanical behavior of near-α titanium alloy and proper design of hot forming, isothermal compression test of TiH₂-based PM near-α type Ti-5.05Al-3.69Zr-1.96Sn-0.32Mo-0.29Si (Ti-1100) alloy was performed at temperatures of 1123–1323 K, strain rates of 0.01-1 s⁻¹, and maximum deformation degree of 60%. The hot deformation characteristics of alloy were analyzed by strain hardening exponent (n), strain rate sensitivity (m), and processing map, along with microstructure observation. The flow stress revealed that the difference in softening/hardening behavior at temperature of 1273–1323 K and the strain rate of 1 s⁻¹ compared to the lower deformation temperature and strain rate. The strain hardening exponents at temperatures of 1123 K are all negative under all strain rates, and the most severe flow softening with minimum value of n was observed at 1123 K and 1 s⁻¹. The strain rate sensitives showed that the peak region with m value greater than 0.5 generally appeared in the high temperature range of 1273–1323 K, while strain rate sensitivity at low temperature behaved differently with strain rates. The processing map developed for strain of 0.6 exhibited high power dissipation efficiency at high temperatures of 1273–1323 K and a low strain rate of 0.01 s⁻¹, due to microstructure evolution of β phase. The decrease of strain rate at 1323 K resulted in the formation of globularization of α lamellae. The instability domain of flow behavior was identified in the temperature range of 1123–1173 K and at the strain rate higher than 0.01 s⁻¹ reflecting the localized plastic flow and adiabatic shear banding, and inhomogenous microstructure. The variation of power dissipation energy (η) slope with strain demonstrated that the power dissipation mechanism during hot deformation has been changed from temperature-dependent to microstructure-dependent with the increase of temperature for the alloy deformed at 0.1 s⁻¹. Eventually, the optimum processing range to deform the material is at 1273–1323 K and a strain rate range of 0.01–0.165 s⁻¹ (ln

\dot{ε}

= −4.6–−1.8). Full article

(This article belongs to the Special Issue Metallurgical Process Simulation and Optimization)

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17 pages, 30724 KiB

Open AccessArticle

In Situ Observation and Phase-Field Simulation Framework of Duplex Stainless-Steel Slab during Solidification

by Tong Wang, David Wexler, Liangliang Guo, Yangfan Wang and Huijun Li

Materials 2022, 15(16), 5517; https://doi.org/10.3390/ma15165517 - 11 Aug 2022

Cited by 3 | Viewed by 1276

Abstract

The melting and solidification process of S32101 duplex stainless steel (DSS) was investigated using high-temperature confocal microscopy (HTCM). The method of concentric HTCM was employed to study microstructure evolution during the solidification process of S32101 DSS. This method could artificially create a meniscus-shaped [...] Read more.

The melting and solidification process of S32101 duplex stainless steel (DSS) was investigated using high-temperature confocal microscopy (HTCM). The method of concentric HTCM was employed to study microstructure evolution during the solidification process of S32101 DSS. This method could artificially create a meniscus-shaped solid–liquid interface, which dramatically improved the quality of in situ observations. During the heating stage, γ-austenite transformed to δ-ferrite, and this transformation manifested itself in the form of grain boundaries (GBs) moving. The effects of cooling rate on the solidification pattern and microstructure were revealed in the present research. An enhanced cooling rate led to a finer microstructure, and the solidification pattern changed from cellular to dendritic growth. As the temperature decreased, the commencement and growth of precipitates were observed. In this paper, the experimental data, including parameters such as temperature, cooling rate, and growth mode, were used as the benchmark for the simulation. A simulation framework using Micress linked to a 1D heat transfer model enabling consistent analysis of solidification dynamics in DSS across the whole cast slab was established. Simulating the dendrite growth and elemental segregation of DSS at specific cooling rates shows that this framework can be a powerful tool for solving practical production problems. Full article

(This article belongs to the Special Issue Metallurgical Process Simulation and Optimization)

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23 pages, 7186 KiB

Open AccessArticle

Numerical Simulation Study of Gas-Solid Heat Transfer and Decomposition Processes of Limestone Calcined with Blast Furnace Gas in a Parallel Flow Regenerative Lime Kiln

by Shaopei Duan, Baokuan Li and Wenjie Rong

Materials 2022, 15(11), 4024; https://doi.org/10.3390/ma15114024 - 06 Jun 2022

Cited by 5 | Viewed by 2985

Abstract

Quicklime is an essential reducing agent in the steel smelting process and its calcination from limestone is accompanied by considerable energy consumption. As a relatively economical lime kiln, the Parallel Flow Regenerative (PFR) lime kiln is used as the main equipment for the [...] Read more.

Quicklime is an essential reducing agent in the steel smelting process and its calcination from limestone is accompanied by considerable energy consumption. As a relatively economical lime kiln, the Parallel Flow Regenerative (PFR) lime kiln is used as the main equipment for the production of quicklime by various steel industries. PFR lime kilns generally use natural gas as the fuel gas. Although natural gas has a high calorific value and is effective in calcination, with the increasing price of natural gas and the pressure saves energy and protect the environment, it makes sense of exploring the use of cleaner energy sources or other sub-products as fuel gas. The use of blast furnace gas (BFG) as a low calorific value fuel gas produced in the steel smelting process has been of interest. This paper therefore develops a set of mathematical models for gas-solid heat transfer and limestone decomposition based on a Porous Medium Model (PMM) and a Shrinking Core Model (SCM) to numerically simulate a PFR lime kiln using BFG in order to investigate the feasibility of calcining limestone with low calorific fuel gas and to provide a valuable reference for future development of such processes and the kiln structure improvement. Full article

(This article belongs to the Special Issue Metallurgical Process Simulation and Optimization)

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19 pages, 5086 KiB

Open AccessArticle

Effect of Flow Field Optimization of an Asymmetric Multi-Strand Tundish on the Quality Consistency of Cracking Con-Rod Steel

by Zhanpeng Tie, Haiyan Tang, Kaimin Wang, Hongsheng Miao, Sen Cai, Fenqiang Xian and Jiaquan Zhang

Materials 2022, 15(10), 3698; https://doi.org/10.3390/ma15103698 - 21 May 2022

Cited by 3 | Viewed by 1424

Abstract

Cracking con-rod is an advanced high-precision connecting structure based on brittle expansion, breaking and reconnection of steel, to solve the problem of assembly circle missing. High carbon micro-alloyed steel C70S6, as a dominant material for the production of cracking con-rod, has extremely strict [...] Read more.

Cracking con-rod is an advanced high-precision connecting structure based on brittle expansion, breaking and reconnection of steel, to solve the problem of assembly circle missing. High carbon micro-alloyed steel C70S6, as a dominant material for the production of cracking con-rod, has extremely strict requirements on non-metallic inclusions in steel and microstructure stability. Continuous casting tundish plays an important role in removing large-sized inclusions and stabilizing casting quality. Aiming at the inconsistent casting quality of C70S6 steel produced by a three-strand asymmetric tundish and the frequent occurrence of slag entrapment problems in Xining Special Steel, the tundish structure was optimized by means of physical modelling combined with numerical simulation, and the quality of the bloom castings and subsequent hot-rolled products before and after optimization were compared based on volume production. The results show that a new flow control design to the tundish can effectively improve the consistency of its metallurgical effect for each of the three strands and the following overall product quality, in which the flow field and temperature field in the tundish are more uniform. This is due to the adoption of a vortex inhibitor and an optimized wall structure according to the measured RTD curve, ink trajectory and numerical simulation on the 3-D streamline contours and temperature distribution in the tundish. The peak concentration of outlet 1 is decreased from 6.5 before optimization to less than 2.0 after optimization, which means the elimination or alleviation of the local short-circuit flow. The maximum temperature difference of C70S6 molten steel measured at the outlets of the tundish three strands is decreased from 2–5 °C to 1–3 °C, which is in good agreement with the numerical simulation results. The difference in columnar crystal ratio of the corresponding bloom castings is decreased from 2.27–3.17% to 1.26–1.85%, and the consistency of central carbon segregation index is also significantly improved. In addition, the difference in oxygen content among the three strand blooms is decreased from 1.7–3.5 ppm to 0.8–1.9 ppm. As a result, the overall mechanical properties and microstructure stability of the hot-rolled products are improved statistically, in which the hardness fluctuation is decreased from 84 HBW to 60 HBW, the inclusion grade of types B + C + D + Ds is reduced to 1.105, and the occurrence rate of Ds dropped to 0.118%. Accordingly, the failure rate of the cracking con-rod is controlled stably within 4‰, and the fracture is generally smoother than that before tundish optimization. In summary, the flow field optimization to a multi-strand asymmetric tundish has a clear effect on improving the overall quality of its bloom castings and rolled products, which should be paid more attention industrially. Meanwhile, the present study provides a reliable theoretical and experimental reference for the improvement of metallurgical effects of an asymmetric-typed tundish commonly used in special steel production. Full article

(This article belongs to the Special Issue Metallurgical Process Simulation and Optimization)

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11 pages, 4059 KiB

Open AccessArticle

Influence of Mineralogical Structure of Mold Flux Film on Heat Transfer in Mold during Continuous Casting of Peritectic Steel

by Lei Liu, Xiuli Han, Mingduo Li and Di Zhang

Materials 2022, 15(9), 2980; https://doi.org/10.3390/ma15092980 - 20 Apr 2022

Cited by 5 | Viewed by 1368

Abstract

The mineralogical structure of flux films is a critical factor in controlling heat transfer in the mold and avoiding the longitudinal cracking of slabs during the continuous casting of peritectic steel. In this study, the layered structure, crystallization ratio, mineralogical species, and morphology [...] Read more.

The mineralogical structure of flux films is a critical factor in controlling heat transfer in the mold and avoiding the longitudinal cracking of slabs during the continuous casting of peritectic steel. In this study, the layered structure, crystallization ratio, mineralogical species, and morphology features of flux films were characterized by optical microscopy, X-ray diffraction, and electron-probe microanalysis. Microstructural observation revealed that the normal flux films for peritectic steels present a multilayered structure and high crystallization ratio (60~90 vol%), mainly composed of well-developed crystalline akermanite and cuspidine. In contrast, the films with outstanding flux characteristics with abundant longitudinal cracks on the slab surface have a low crystallization ratio (<50 vol%) or vast crystallite content (>80 vol%). Furthermore, heat transfer analysis showed that the low crystallization ratio and the vast crystallite content of flux films worsen the heat transfer rate or uniformity in the mold, whereas the appropriate thickness and cuspidine content of flux films can improve the heat transfer performance. From the above results, it is concluded that using strong crystalline flux to obtain the ideal mineral phase structure of flux film is one of the important measures for reducing longitudinal cracks during continuous casting of peritectic steel slabs. Full article

(This article belongs to the Special Issue Metallurgical Process Simulation and Optimization)

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18 pages, 7666 KiB

Open AccessArticle

Mesoscopic Fluid-Particle Flow and Vortex Structural Transmission in a Submerged Entry Nozzle of Continuous Caster

by Peng Zhao, Rongxun Piao and Zongshu Zou

Materials 2022, 15(7), 2510; https://doi.org/10.3390/ma15072510 - 29 Mar 2022

Cited by 4 | Viewed by 1486

Abstract

Understanding the essence of the flow oscillations within a submerged-entry nozzle (SEN) is essential to control flow patterns in the continuous casting mold and consequently increase the superficial quality of steel products. A numerical study of the mesoscopic fluid-particle flow in a bifurcated [...] Read more.

Understanding the essence of the flow oscillations within a submerged-entry nozzle (SEN) is essential to control flow patterns in the continuous casting mold and consequently increase the superficial quality of steel products. A numerical study of the mesoscopic fluid-particle flow in a bifurcated pool-type SEN under steady operating conditions is conducted using the lattice Boltzmann method (LBM) coupled with the large eddy simulation (LES) model. The accuracy of the model has been verified by comparing vortex structures and simulated velocities with published experimental values. The LBM modeling is also verified by comparing the “stair-step” jet patterns observed in the experiment. The geometrical parameters and operational conditions of physical experiments are reproduced in the simulations. By comparing the time-averaged velocities of Reynolds-averaged Navier–Stokes equations (RANS) with LBM models, transient mesoscopic fluid-particles and related vortex structures can be better reproduced within the SEN. The visualization of internal flow within the SEN is illustrated through the mass-less Discrete Phase Model (DPM) model. The trajectories show that the LBM–LES–DPM coupled model is good at predicting the transient vortical flow within the SEN. A large vortex is found inside the exit port and continuously changes in shape and size therein. The monitoring points and lines within the SEN are selected to illustrate the velocity variations and effective viscosity, which can reflect the oscillating characteristics even under stable operating conditions without changes at the exit from the SEN. Furthermore, the formation, development, diffusion, and dissipation of the vortex structures from the exit port of the SEN are also investigated using the Q criteria. The comparison of the power spectrum with high-frequency components along the exit port indicates that the flow oscillations must originate from within the SEN and are intensified in the exit port. The mesoscopic LBM model can replicate the fluid-particle flow and vortex structure transmission as well as their turbulence effects inside the SEN in detail. Full article

(This article belongs to the Special Issue Metallurgical Process Simulation and Optimization)

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16 pages, 4775 KiB

Open AccessArticle

The Effect of Heat Source Path on Thermal Evolution during Electro-Gas Welding of Thick Steel Plates

by Jun Fu, Qing Tao, Xiaoan Yang, Bogdan Nenchev, Ming Li, Biao Tao and Hongbiao Dong

Materials 2022, 15(6), 2215; https://doi.org/10.3390/ma15062215 - 17 Mar 2022

Cited by 4 | Viewed by 1562

Abstract

In recent years, the shipbuilding industry has experienced a growing demand for tighter control and higher strength requirements in thick steel plate welding. Electro-gas welding (EGW) is a high heat input welding method, widely used to improve the welding efficiency of thick plates. [...] Read more.

In recent years, the shipbuilding industry has experienced a growing demand for tighter control and higher strength requirements in thick steel plate welding. Electro-gas welding (EGW) is a high heat input welding method, widely used to improve the welding efficiency of thick plates. Modelling the EGW process of thick steel plates has been challenging due to difficulties in accurately depicting the heat source path movement. An EGW experiment on 30 mm thickness E36 steel plates was conducted in this study. A semi-ellipsoid heat source model was implemented, and its movement was mathematically expressed using linear, sinusoidal, or oscillate-stop paths. The geometry of welding joints, process variables, and steel composition are taken from industrial scale experiments. The resulting thermal evolutions across all heat source-path approaches were verified against experimental observations. Practical industrial recommendations are provided and discussed in terms of the fusion quality for E36 steel plates with a heat input of 157 kJ/cm. It was found that the oscillate-stop heat path predicts thermal profile more accurately than the sinusoidal function and linear heat path for EGW welding of 30 mm thickness and above. The linear heat path approach is recommended for E36 steel plate thickness up to 20 mm, whereas maximum thickness up to 30 mm is appropriate for sinusoidal path, and maximum thickness up to 35 mm is appropriate for oscillate-stop path in EGW welding, assuming constant heat input. Full article

(This article belongs to the Special Issue Metallurgical Process Simulation and Optimization)

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14 pages, 1324 KiB

Open AccessArticle

Exploratory Data Analysis for the Evaluation of Tribological Properties of Wear-Resistant Surface Layers Modified with Rare-Earth Metals

by Paweł Malinowski, Justyna Kasińska, Sławomir Rutkowski and Monika Madej

Materials 2022, 15(6), 2032; https://doi.org/10.3390/ma15062032 - 09 Mar 2022

Cited by 4 | Viewed by 1855

Abstract

The role of rare Earth metals in the improvement of the properties of metals and alloys has been analysed and described in multiple studies. Their effects on changes in microstructure and mechanical properties are most pronounced. This paper focuses on the beneficial effect [...] Read more.

The role of rare Earth metals in the improvement of the properties of metals and alloys has been analysed and described in multiple studies. Their effects on changes in microstructure and mechanical properties are most pronounced. This paper focuses on the beneficial effect of rare Earth metal oxides on the wear resistance of surface layers applied to castings intended for structural elements of machinery and equipment in mining and recycling. The experiment involved modifying prepared surfaces by adding CeO₂, Y₂O₃, and La₂O₃. Hardness measurements, a scratch test, and tribological tests were performed under dry and fluid friction. The maximum wear track depth and track area were measured from the surface profile. To determine correlations between the results, exploratory data analysis was employed. Heatmaps were used to illustrate strong positive and negative interactions. The addition of oxides at increasing carbon content resulted in increased hardness, lower coefficient of friction, and reduced track area and maximum track depth. Strong negative interactions between the track area and maximum track depth were found. The differences resulting from the test conditions (fluid and dry friction) were discussed. This study demonstrated the suitability of exploratory data analysis for analysing research results and confirmed the improvement of modified surface wear resistance. Full article

(This article belongs to the Special Issue Metallurgical Process Simulation and Optimization)

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21 pages, 6365 KiB

Open AccessArticle

Integrating a Top-Gas Recycling and CO₂ Electrolysis Process for H₂-Rich Gas Injection and Reduce CO₂ Emissions from an Ironmaking Blast Furnace

by Yichao Hu, Yinxuan Qiu, Jian Chen, Liangyuan Hao, Thomas Edward Rufford, Victor Rudolph and Geoff Wang

Materials 2022, 15(6), 2008; https://doi.org/10.3390/ma15062008 - 08 Mar 2022

Cited by 7 | Viewed by 3134

Abstract

Introducing CO₂ electrochemical conversion technology to the iron-making blast furnace not only reduces CO₂ emissions, but also produces H₂ as a byproduct that can be used as an auxiliary reductant to further decrease carbon consumption and emissions. With adequate H [...] Read more.

Introducing CO₂ electrochemical conversion technology to the iron-making blast furnace not only reduces CO₂ emissions, but also produces H₂ as a byproduct that can be used as an auxiliary reductant to further decrease carbon consumption and emissions. With adequate H₂ supply to the blast furnace, the injection of H₂ is limited because of the disadvantageous thermodynamic characteristics of the H₂ reduction reaction in the blast furnace. This paper presents thermodynamic analysis of H₂ behaviour at different stages with the thermal requirement consideration of an iron-making blast furnace. The effect of injecting CO₂ lean top gas and CO₂ conversion products H₂–CO gas through the raceway and/or shaft tuyeres are investigated under different operating conditions. H₂ utilisation efficiency and corresponding injection volume are studied by considering different reduction stages. The relationship between H₂ injection and coke rate is established. Injecting 7.9–10.9 m³/tHM of H₂ saved 1 kg/tHM coke rate, depending on injection position. Compared with the traditional blast furnace, injecting 80 m³/tHM of H₂ with a medium oxygen enrichment rate (9%) and integrating CO₂ capture and conversion reduces CO₂ emissions from 534 to 278 m³/tHM. However, increasing the hydrogen injection amount causes this iron-making process to consume more energy than a traditional blast furnace does. Full article

(This article belongs to the Special Issue Metallurgical Process Simulation and Optimization)

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14 pages, 2462 KiB

Open AccessArticle

Multi-Parameter Characteristics of Electric Arc Furnace Melting

by Michał Moskal, Piotr Migas and Mirosław Karbowniczek

Materials 2022, 15(4), 1601; https://doi.org/10.3390/ma15041601 - 21 Feb 2022

Cited by 4 | Viewed by 2009

Abstract

The article presents the results of analyses of numerical modelling of selected factors in electric arc furnace melts. The aim of the study was to optimise the melting process in an electric arc furnace using statistical-thermodynamic modelling based on, among other things, multiple [...] Read more.

The article presents the results of analyses of numerical modelling of selected factors in electric arc furnace melts. The aim of the study was to optimise the melting process in an electric arc furnace using statistical-thermodynamic modelling based on, among other things, multiple linear regression (MLR). The article presents tools and methods which make it possible to identify the most significant indicators of the process carried out on the analysed unit from the point of view of improvement. The article presents the characteristics of the process and creation of the MLR model and, by applying its numerical analyses and results of calculations and simulations for selected variables and indicator, identifying the operation of a selected furnace. Developed model to demand of electric energy identification was used for calculations of energy balances, the distribution of the energy used in the furnace was presented. Full article

(This article belongs to the Special Issue Metallurgical Process Simulation and Optimization)

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16 pages, 7656 KiB

Open AccessArticle

Effect of Cerium on the Microstructure and Inclusion Evolution of C-Mn Cryogenic Vessel Steels

by Liping Wu, Jianguo Zhi, Jiangshan Zhang, Bo Zhao and Qing Liu

Materials 2021, 14(18), 5262; https://doi.org/10.3390/ma14185262 - 13 Sep 2021

Cited by 7 | Viewed by 1560

Abstract

The effects of Cerium (Ce) were studied on the casting slab quality, microstructure, and inclusion evolution of cryogenic vessel steel. An optical metallographic microscope, scanning electron microscope, energy dispersive spectrometer, and Thermo-calc thermodynamic software were used for characterization and analysis. The results indicated [...] Read more.

The effects of Cerium (Ce) were studied on the casting slab quality, microstructure, and inclusion evolution of cryogenic vessel steel. An optical metallographic microscope, scanning electron microscope, energy dispersive spectrometer, and Thermo-calc thermodynamic software were used for characterization and analysis. The results indicated that the central segregation was significantly improved after adding Ce and reached the lowest level when the content of Ce was 0.0009 wt.%. Meanwhile, the presence of Ce reduces the size of ferrite and improves pearlite morphology. Ce also enables the modification of Al₂O₃ and MnS + Ti₄C₂S₂ inclusions into ellipsoid CeAlO₃ and spherical Ce₂O₂S + Ti₄C₂S₂ composite inclusions, respectively, which are easier to remove. The formed Ce₂O₂S inclusions are fine and can work as heterogeneous nucleation points to refine the microstructure of steel. Full article

(This article belongs to the Special Issue Metallurgical Process Simulation and Optimization)

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16 pages, 5429 KiB

Open AccessArticle

Full-Field Temperature Measurement of Stainless Steel Specimens Subjected to Uniaxial Tensile Loading at Various Strain Rates

by Krzysztof Żaba, Tomasz Trzepieciński, Stanislav Rusz, Sandra Puchlerska and Maciej Balcerzak

Materials 2021, 14(18), 5259; https://doi.org/10.3390/ma14185259 - 13 Sep 2021

Cited by 6 | Viewed by 1775

Abstract

This article presents a study on the effect of strain rate, specimen orientation, and plastic strain on the value and distribution of the temperature of dog-bone 1 mm-thick specimens during their deformation in uniaxial tensile tests. Full-field image correlation and infrared thermography techniques [...] Read more.

This article presents a study on the effect of strain rate, specimen orientation, and plastic strain on the value and distribution of the temperature of dog-bone 1 mm-thick specimens during their deformation in uniaxial tensile tests. Full-field image correlation and infrared thermography techniques were used. A titanium-stabilised austenitic 321 stainless steel was used as test materials. The dog-bone specimens used for uniaxial tensile tests were cut along the sheet metal rolling direction and three strain rates were considered: 4 × 10⁻³ s⁻¹, 8 × 10⁻³ s⁻¹ and 16 × 10⁻³ s⁻¹. It was found that increasing the strain rate resulted in the intensification of heat generation. High-quality regression models (Ra > 0.9) developed for the austenitic 321 steel revealed that sample orientation does not play a significant role in the heat generation when the sample is plastically deformed. It was found that at the moment of formation of a necking at the highest strain rate, the maximum sample temperature increased more than four times compared to the initial temperature. A synergistic effect of the strain hardening exponent and yield stress revealed that heat is generated more rapidly towards small values of strain hardening exponent and yield stress. Full article

(This article belongs to the Special Issue Metallurgical Process Simulation and Optimization)

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17 pages, 6937 KiB

Open AccessArticle

Influence of M-EMS on Fluid Flow and Initial Solidification in Slab Continuous Casting

by Guoliang Liu, Haibiao Lu, Bin Li, Chenxi Ji, Jiangshan Zhang, Qing Liu and Zuosheng Lei

Materials 2021, 14(13), 3681; https://doi.org/10.3390/ma14133681 - 01 Jul 2021

Cited by 7 | Viewed by 1946

Abstract

A mathematical model coupled with electromagnetic field has been developed to simulate the transient turbulence flow and initial solidification in a slab continuous casting mold under different electromagnetic stirring (EMS) currents and casting speeds. Through comparing the magnetic flux density, flow field with [...] Read more.

A mathematical model coupled with electromagnetic field has been developed to simulate the transient turbulence flow and initial solidification in a slab continuous casting mold under different electromagnetic stirring (EMS) currents and casting speeds. Through comparing the magnetic flux density, flow field with measured results, the reliability of the mathematical model is proved. The uniform index of solidified shell thickness has been introduced to judge the uniformity of the solidified shell. The results show that a horizonal recirculation flow has been generated when EMS is applied, and either accelerated or decelerated regions of flow field are formed in the liquid pool. Large EMS current and low casting speed may cause the plug flow near the mold narrow face and a suitable EMS current can benefit to the uniform growth of solidified shell. Meanwhile, an industrial test exhibits that EMS can weaken the level fluctuation and number density of inclusion. Overall, a rational EMS current range is gained, when the casting speed is 1.2 m/min, the rational EMS current is 500–600 A. Full article

(This article belongs to the Special Issue Metallurgical Process Simulation and Optimization)

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10 pages, 1718 KiB

Open AccessFeature PaperArticle

Study of Interaction Mechanism between Positrons and Ag Clusters in Dilute Al–Ag Alloys at Low Temperature

by Xiaoshuang Liu, Peng Zhang, Baoyi Wang, Xingzhong Cao, Shuoxue Jin and Runsheng Yu

Materials 2021, 14(6), 1451; https://doi.org/10.3390/ma14061451 - 16 Mar 2021

Cited by 4 | Viewed by 1509

Abstract

The microstructural evolution of dilute Al–Ag alloys in its early aging stage and at low temperatures ranging from 15 K to 300 K was studied by the combined use of Positron annihilation lifetime spectroscopy (PALS), high resolution transmission electron microscopy (HRTEM), and positron [...] Read more.

The microstructural evolution of dilute Al–Ag alloys in its early aging stage and at low temperatures ranging from 15 K to 300 K was studied by the combined use of Positron annihilation lifetime spectroscopy (PALS), high resolution transmission electron microscopy (HRTEM), and positron annihilation Coincidence Doppler broadening (CDB) techniques. It is shown that at low temperatures below 200 K, an Ag–vacancy complex is formed in the quenched alloy, and above 200 K, it decomposes into Ag clusters and monovacancies. Experimental and calculation results indicate that Ag clusters in Al–Ag alloys can act as shallow trapping sites, and the positron trapping rate is considerably enhanced by a decreasing measurement temperature. Full article

(This article belongs to the Special Issue Metallurgical Process Simulation and Optimization)

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