Article
Materials Science, Multidisciplinary
Clodualdo Aranas, Fulvio Siciliano, Samuel Filgueiras Rodrigues, Jubert Pasco, Edson J. P. Miranda, John Joseph Jonas
Summary: This study analyzed the deformation behavior and thermodynamic aspects of four different steel grades, revealing that under hot deformation conditions, Nb microalloyed steels produce more ferrite than C-Mn steel, while X-80 steel yields less ferrite than X-70 steel. The concept of transformation softening was applied to explain the occurrence of dynamic transformation during hot torsion tests.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2021)
Article
Nanoscience & Nanotechnology
Adam Grajcar, Adam Skowronek, Krzysztof Radwanski
Summary: The research shows that controlling the microstructure and size of retained austenite in multiphase steels can affect their mechanical properties, and it is necessary to produce dispersed retained austenite of different sizes for the TRIP effect instead of striving for maximum fragmentation.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Materials Science, Multidisciplinary
Yan Peng, Shuo Guo, Caiyi Liu, Silvia Barella, Shicheng Liang, Andrea Gruttadauria, Carlo Mapelli
Summary: This paper investigates the DRX behavior of low carbon steel, revealing the effect of temperature and strain rate on DRX through hot compression tests and a established kinetic model. Additionally, the DRX behavior during hot rolling is simulated, and it is found that the non-uniform distribution of DRX is related to high-temperature deformation.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2022)
Article
Materials Science, Multidisciplinary
Youliang He, Erik J. Hilinski
Summary: In this study, a special rolling technique called skew rolling was used to investigate the effect of cold rolling deformation mode and initial texture on the final textures of non-oriented electrical steels. The results showed that the unconventional rolling technique altered the initial textures and induced significantly different cold-rolling and recrystallization textures compared to conventional rolling.
Article
Materials Science, Multidisciplinary
Alisson Paulo de Oliveira, Berenice Mendonca Gonzalez
Summary: Boron has the potential to enhance the mechanical properties of niobium and titanium high-strength low-alloy steel. However, its effect on toughness is controversial, which is why boron addition is not recommended for shipbuilding and line pipe steel grades.
JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE
(2022)
Article
Materials Science, Multidisciplinary
Yihui Jiang, Xingde Zhang, Pengtao Cai, Pengtao Li, Fei Cao, Fan Gao, Shuhua Liang
Summary: A recently discovered Cu-Hf alloy has shown promise in the fabrication of high-strength and high electrical conductivity materials. However, the precipitation behavior and microstructural evolution during thermo-mechanical processing have not been well understood. This study focused on the crystallography, thermodynamics, and kinetics of precipitation during isothermal aging and the interaction between nano-precipitates and nano-twins during liquid nitrogen temperature rolling in Cu-Hf alloys. The results showed that the isothermal aging precipitation of Cu-Hf alloys involved the formation of supersaturated FCC-Cu, coherent Cu5Hf phase, and incoherent Cu51Hf14 phase. The formation of the Cu5Hf phase was attributed to the lower energy and interfacial free energy of coherent nano-precipitates, resulting in shape changes in the nano-precipitates. Molecular dynamics simulations revealed that the pre-existing nano-precipitates significantly improved the twinning ability of the Cu-Hf alloy, leading to the formation of numerous nano-twin bundles during low-temperature rolling. Finally, a new type of Cu-Hf based alloy with excellent combination of high strength, high electrical conductivity, and high heat-resistance was successfully fabricated using routine processes.
Article
Chemistry, Physical
Aneta Lukaszek-Solek, Tomasz Sleboda, Lukasz Lisiecki, Janusz Krawczyk
Summary: The paper presents the hot deformation behavior of 4130 steel and the optimization of its processing parameters. Compression tests were conducted at various temperatures and strain rates to analyze material behavior under different thermomechanical conditions. The flow-stress curves and processing maps obtained from the tests were discussed.
Article
Materials Science, Multidisciplinary
Yunjie Bi, Rui Ge, Ming Yan, Xiaojing Xiong
Summary: The continuously annealed low-carbon-steel strips from industrial production have an average aging index of about 30 N/mm(2). The increase in yield strength caused by continuous annealing is dependent on soaking temperature and time. Although optimization of overaging parameters and higher annealing temperature can reduce aging susceptibility, it is unlikely to reach the same level as batch-annealed steel. Carbon content has little effect on aging within low-carbon-strip specifications. Aging index of temper-rolled materials decreases with increasing temper-rolling reductions, with maximum yield strength achieved at a decrease of about 1%. The study examines the effect of carbon and aluminum content, continuous-annealing cycles, and temper-rolling reduction on aging susceptibility of continuously annealed low-carbon-steel strips, using SEM/EBSD technique to characterize temper-rolling strain bands and assess the effect on yield strength.
Article
Engineering, Mechanical
Yousef Mohammadi, Hossein Amirabadi
Summary: This study presents an analytical solution to calculate the work hardening in the milling process, using the Johnson-Cook material model to calculate flow stress. Experimental validation shows that the model can accurately predict the amount of work hardening.
JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY
(2022)
Article
Nanoscience & Nanotechnology
A. Reitz, O. Grydin, M. Schaper
Summary: This study investigates the design and transformation kinetics of load-adapted components for reducing CO2 emissions in the transport sector. The experimental analysis reveals the interactions among process parameters and the significant influence of soaking duration on microstructure.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Materials Science, Multidisciplinary
A. Esmaeilpour, H. R. Abedi, A. Mirzaei, A. Habibiyan
Summary: This study investigates the high temperature flow behavior of additively manufactured 316 L stainless steel through hot compression tests. By using an Artificial Neural Network model, the flow curves of the material at different temperatures and strain rates were accurately predicted.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2022)
Article
Engineering, Multidisciplinary
Xiaoming Wang, Boyang An, Qing He, Ping Wang, Wenjian Wang, Jun Huang
Summary: This study proposes a novel thermomechanical coupled modeling method using a nonlocal peridynamic approach for rolling contacts with temperature-dependent adjacent material or contact surface discontinuities. Fully coupled, ordinary state-based PD thermomechanical equations are derived and an algorithm for rolling thermal contacts in PD is proposed. The study also provides a detailed modeling process and algorithm for the proposed method based on a multi-rate time-integration scheme. The method is evaluated using a 2D wheel-rail rolling contact model, showing good agreement with analytical solutions and revealing the effects of temperature-dependent material and rail-surface cracks on the thermomechanical response.
APPLIED MATHEMATICAL MODELLING
(2023)
Article
Engineering, Mechanical
Anton Evdokimov, Nikolay Doynov, Ralf Ossenbrink, Aleksei Obrosov, Sabine Weiss, Vesselin Michailov
Summary: A numerical model was developed to compute distortions in laser-welded dissimilar overlap joints, considering properties of mixed steel-aluminum weld metal. Experimental results showed that the developed weld material model significantly improves the accuracy of thermomechanical simulations, with good agreement between computed and measured data.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2021)
Article
Chemistry, Physical
Jizhen Wang, Miao Han, Chong Zhang, Hasib Md Abu Rayhan, Xvyang Li, Yanshan Lou
Summary: By combining experimental and theoretical models, this research investigates the anisotropic hardening behaviors of TRIP780 steel. The experimental results show that TRIP780 steel exhibits anisotropic characteristics in terms of strength and plastic deformation. Comparing different models, the Chen-CQN function demonstrates better numerical implementation and more realistic prediction of yield stress for the TRIP780 steel sheet.
Article
Materials Science, Multidisciplinary
Ling Qiao, Yong Liu, Jingchuan Zhu, Zibo Wang
Summary: The study successfully predicted the correlation between alloying elements and hardening exponent using the optimized GRNN model, confirming the practicality of this approach in industrial application design.
Article
Engineering, Mechanical
Kofi A. Annan, Eric G. Njoroge, Charles W. Siyasiya, Roelf Mostert
Summary: An unexpected explosion of a fifty litre seamless gas cylinder, in service for five years, was caused by fluorine attack on the steel despite good mechanical and material properties as well as manufacturing practices.
ENGINEERING FAILURE ANALYSIS
(2021)
Article
Materials Science, Multidisciplinary
M. N. Mathabathe, A. S. Bolokang, G. Govender, C. W. Siyasiya, R. J. Mostert
Summary: The thermal, surface properties and microstructures of the nitrided gamma-Ti-46Al-2Nb and Ti-46Al-2Nb-0.7Cr-0.3Si intermetallic alloys were investigated. Thin nitride layers formed on both alloys after annealing and nitridation under nitrogen gas, exhibiting surface spallation at different rates during cyclic oxidation. XPS analysis revealed the presence of mixed oxide layer near the Ti-46Al-2Nb-0.7Cr-0.3Si surface.
MATERIALS CHEMISTRY AND PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
N. K. K. Arthur, C. Siyasiya, S. Pityana, M. Tlotleng
Summary: This study investigates the use of direct energy deposition technique in additive manufacturing for alloy development, successfully improving the ductility and part performance of LENS produced titanium alloys by implementing effective heat inputs. The addition of molybdenum as a beta-stabilizing alloying element led to an increase in volume fraction of the beta-phase and a transition from planar to cellular solidification, resulting in hardness values attributed to the beta-stabilizing and grain refining effect of refractory metals like molybdenum.
JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE
(2021)
Article
Nanoscience & Nanotechnology
K. M. Lekganyane, R. J. Mostert, C. W. Siyasiya, K. M. Banks
Summary: The hot ductility of a low carbon peritectic steel grade was investigated, showing that terminating primary cooling at temperatures 70°C above the ferrite start transformation temperature resulted in poor ductility. The formation of thin ferrite films during rebound heating led to irreversible loss of hot ductility due to finely dispersed second phase particles remaining at the austenite grain boundaries.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Chemistry, Physical
P. Daswa, S. Chikosha, C. W. Siyasiya
Summary: The study investigated the effects of substituting varying amounts of vanadium for titanium in TiPt shape memory alloy on microstructure, crystal structure, and phase transformation. The results demonstrated that the addition of vanadium improved the functional properties and increased the martensitic transformation temperature of TiPt.
Article
Metallurgy & Metallurgical Engineering
Ya-dong Wang, Zheng-hua Tang, Su-fen Xiao, Charles W. Siyasiya, Tao Wei
Summary: The study focused on the strength-to-weight ratio of high-strength low-alloy steel used in pipelines and investigated the effects of thermo-mechanical controlled processing on precipitates and microstructure. The optimized parameters combination was found to be FRT of 820 degrees C and CT of 550 degrees C, resulting in a precipitates volume fraction of 0.59%.
JOURNAL OF IRON AND STEEL RESEARCH INTERNATIONAL
(2022)
Article
Materials Science, Multidisciplinary
Oleary Bill, Charles Siyasiya, Joseph Moema
Summary: The hot deformation behavior of 2304 lean duplex stainless steel was studied using processing maps and physically based constitutive modeling. The results showed that dynamic restoration mechanisms can prevent flow instability at low strain rates, and for typical industrial purposes, hot working at higher strain rates is possible without the risk of instability by promoting dynamic recrystallization in the austenitic phase.
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
(2022)
Article
Materials Science, Multidisciplinary
Tulani W. Mukarati, Roelf J. Mostert, Charles W. Siyasiya, Waldo E. Stumpf
Summary: Boltzmann-type sigmoidal equations have been developed to model the tensile strain hardening and flow stress behavior of a metastable AISI 301LN austenitic stainless steel subjected to prior cold deformation. The compressive pre-strain has a strong effect on the material's martensite content, tensile yield strength, and energy absorption capability.
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
(2022)
Article
Metallurgy & Metallurgical Engineering
Tulani W. Mukarati, Roelf J. Mostert, Charles W. Siyasiya
Summary: This study investigates the mechanical properties of a lean AISI 301LN austenitic stainless steel under various temperature and strain conditions, revealing the influence of martensite transformation strengthening on the material's behavior. Various measurement techniques are used to accurately describe the kinetics of strain-induced martensite transformation at different temperatures, providing insights into the alloy's performance at different operating conditions.
STEEL RESEARCH INTERNATIONAL
(2022)
Article
Engineering, Mechanical
Tshenolo Phinah Leso, Charles Witness Siyasiya, Roelf Johannes Mostert, Joseph Moema
Summary: Wear and rolling contact fatigue (RCF) are major issues in rail systems, but the presence of lubricants can help reduce their effects. This study focused on the use of water and oil as lubricants, finding that they significantly decreased wear compared to dry conditions. Water was found to cause fluid crack pressurization, leading to RCF.
TRIBOLOGY TRANSACTIONS
(2023)
Review
Materials Science, Multidisciplinary
John J. M. Ellard, Maria N. Mathabathe, Charles W. Siyasiya, Amogelang S. Bolokang
Summary: Relentless efforts over the past decade have led to the commercialization of lightweight high-temperature β-TiAl-based intermetallic alloys. These materials have been used in General Electric's (GE) high bypass turbofan aircraft engines for the Boeing 787 as well as in the PW1100GTF engines for low-pressure turbine (LPT) blades. To enhance the fatigue resistance of the alloys, a clear understanding of their response to fatigue loading is crucial. This review provides a detailed discussion on the low-cycle fatigue (LCF) behavior of β-TiAl-based alloys, including crack initiation, propagation, fracture mechanisms, and the influence of temperature and environment on cyclic deformation mechanisms and fatigue life. Additionally, the review presents comprehensive discussions on modeling and prediction of fatigue properties, as well as effective methods for optimizing the microstructures of β-TiAl-based alloys to improve LCF behavior.
Article
Materials Science, Multidisciplinary
Joseph S. Moema, Charles W. Siyasiya, Veronica K. Morudu, Thokozani Buthelezi
Summary: Due to the increasing demand for energy saving, the need for high-performing automotive heat exchangers has grown significantly. Effective fin-tube heat exchangers, made from AA3003 aluminum alloy, have become popular. The impact of soaking time on the microstructure and mechanical properties of AA3003 cladded with AA4045 alloy was investigated. Precise control of various manufacturing steps is crucial to achieve a high-quality product.
Article
Metallurgy & Metallurgical Engineering
M. G. Willemse, C. W. Siyasiya, D. Marais, A. M. Venter', N. K. K. Arthur
Summary: This research project focuses on the evolution of residual stresses in 3D printed titanium alloy samples. The study found that there were large tensile stresses near the top sections of the samples, which could lead to separation from the baseplate. Additionally, the analysis of microstructures revealed a strong correlation between the macro-segregation of nickel elements and the distribution of the beta phase in the printed parts.
JOURNAL OF THE SOUTHERN AFRICAN INSTITUTE OF MINING AND METALLURGY
(2023)
Article
Metallurgy & Metallurgical Engineering
M. N. Mathabathe, A. S. Bolokang, G. Govender, C. W. Siyasiya, R. J. Mostert
Summary: A series of solidifying γ-TiAl intermetallic alloys were developed and tensile tested at room temperature, showing predominantly lamellar structures with columnar dendritic cores and occasional presence of second phase Ti5Si3. All alloys exhibited brittleness with no detectable ductility during tensile deformation. Fracture surfaces revealed translamellar fracture with few cleavage facets.
JOURNAL OF THE SOUTHERN AFRICAN INSTITUTE OF MINING AND METALLURGY
(2021)
Proceedings Paper
Materials Science, Multidisciplinary
K. A. Annan, P. Daswa, K. Motumbo, C. W. Siyasiya
Summary: Titanium aluminides are considered the optimal materials for specific applications in aerospace and automotive industries due to their high specific strength and high temperature performance, coupled with good oxidation resistance. The production process of these materials greatly influences their mechanical properties.
MATERIALS TODAY-PROCEEDINGS
(2021)
