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Full-Text Articles in Science and Technology Studies
Performance Of Ballast Influenced By Deformation And Degradation: Laboratory Testing And Numerical Modeling, Buddhima Indraratna, Ngoc Trung Ngo, Cholachat Rujikiatkamjorn
Performance Of Ballast Influenced By Deformation And Degradation: Laboratory Testing And Numerical Modeling, Buddhima Indraratna, Ngoc Trung Ngo, Cholachat Rujikiatkamjorn
Faculty of Engineering and Information Sciences - Papers: Part B
This paper presents a study on the deformation and degradation responses of railway ballast using large-scale laboratory testing and computational modeling approaches. A series of large-scale triaxial tests were carried out to investigate the ballast breakage responses under cyclic train loading subjected to varying frequencies, f=10-40 Hz. The role of recycled rubber energy-absorbing mats (REAMs) on reducing ballast breakage was also examined. Laboratory test results show that the ballast experiences significant degradation (breakage) and deformation, while the inclusion of REAMs can reduce the ballast breakage up to about 35%. Numerical modeling using the coupled discrete-continuum approach [coupled discrete-element method-finite-difference method …
Two Decades Of Advancement In Process Simulation Testing Of Ballast Strength, Deformation, And Degradation, Buddhima Indraratna, Ngoc Trung Ngo, Sanjay Nimbalkar, Cholachat Rujikiatkamjorn
Two Decades Of Advancement In Process Simulation Testing Of Ballast Strength, Deformation, And Degradation, Buddhima Indraratna, Ngoc Trung Ngo, Sanjay Nimbalkar, Cholachat Rujikiatkamjorn
Faculty of Engineering and Information Sciences - Papers: Part B
This paper describes salient features of a set of large-scale ballast testing equipment developed at the University of Wollongong, Australia, and how the test results and research outcomes have contributed to transforming tracks in the Australian heavy haul and commuter networks, particularly with regards to the strength, deformation, and degradation of ballast. Ideally, ballast assemblies should be tested in prototype scale under actual loading conditions. This is because a reduction in particle sizes for testing in smaller equipment can reduce the internal angle of friction (shearing resistance) of the granular assembly in a macro sense, and the angularity of the …
Application Of Fractional Calculus In Modelling Ballast Deformation Under Cyclic Loading, Yifei Sun, Buddhima Indraratna, John Philip Carter, Timothy R. Marchant, Sanjay Nimbalkar
Application Of Fractional Calculus In Modelling Ballast Deformation Under Cyclic Loading, Yifei Sun, Buddhima Indraratna, John Philip Carter, Timothy R. Marchant, Sanjay Nimbalkar
Faculty of Engineering and Information Sciences - Papers: Part A
Most constitutive models can only simulate cumulative deformation after a limited number of cycles. However, railroad ballast usually experiences a large number of train passages that cause history-dependent long-term deformation. Fractional calculus is an efficient tool for modelling this phenomenon and therefore is incorporated into a constitutive model for predicting the cumulative deformation. The proposed model is further validated by comparing the model predictions with a series of corresponding experimental results. It is observed that the proposed model can realistically simulate the cumulative deformation of ballast from the onset of loading up to a large number of load cycles.
A Framework To Assess Newmark-Type Simplified Methods For Evaluation Of Earthquake-Induced Deformation Of Embankments, Mojtaba E. Kan, Hossein Taiebat, Mahdi Taiebat
A Framework To Assess Newmark-Type Simplified Methods For Evaluation Of Earthquake-Induced Deformation Of Embankments, Mojtaba E. Kan, Hossein Taiebat, Mahdi Taiebat
Faculty of Engineering and Information Sciences - Papers: Part A
The simplified procedures for evaluation of the earthquake induced displacement in earth and rockfill dams are widely used in practice. These methods are simple, inexpensive, and substantially less time consuming as compared to the complicated stress-deformation approaches. They are especially recommended to be used as a screening tool, to identify embankments with marginal factor of safety, assuming that these methods always give conservative estimates of settlements. However recent studies show that application of these methods may not be conservative in some cases, especially when the tuning ratio of a dam is within a certain range. In this paper the fundamental …
Effect Of Deformation On Microstructure And Mechanical Properties Of Dual Phase Steel Produced Via Strip Casting Simulation, Zhiping Xiong, Andrii Kostryzhev, Nicole Stanford, Elena V. Pereloma
Effect Of Deformation On Microstructure And Mechanical Properties Of Dual Phase Steel Produced Via Strip Casting Simulation, Zhiping Xiong, Andrii Kostryzhev, Nicole Stanford, Elena V. Pereloma
Faculty of Engineering and Information Sciences - Papers: Part A
The strip casting is a recently appeared technology with a potential to significantly reduce energy consumption in steel production, compared to hot rolling and cold rolling. However, the quantitative dependences of the steel microstructure and mechanical properties on strip casting parameters are unknown and require investigation. In the present work we studied the effects of strain and interrupted cooling temperature on microstructure and mechanical properties in conventional dual phase steel (0.08C-0.81Si-1.47Mn-0.03Al wt%). The strip casting process was simulated using a Gleeble 3500 thermo-mechanical simulator. The steel microstructures were studied using optical, scanning and transmission electron microscopy. Mechanical properties were measured …
An Elasto-Plastic Method For Analysing The Deformation Of The Railway Ballast, Qideng Sun, Buddhima Indraratna, Sanjay Nimbalkar
An Elasto-Plastic Method For Analysing The Deformation Of The Railway Ballast, Qideng Sun, Buddhima Indraratna, Sanjay Nimbalkar
Faculty of Engineering and Information Sciences - Papers: Part A
In this study, a series of monotonically drained triaxial tests were conducted using the large-scale cylindrical triaxial apparatus. The effect of particle breakage and confining pressure on the mechanical behaviour of ballast were investigated. Based on the experimental findings, mathematical expressions for critical state stress ratio and specific volume are proposed to incorporate the evolution of particle breakage during monotonic shearing. An elasto-plastic constitutive model is formulated within the critical state soil mechanics framework in order to capture the stress-strain behaviour and degradation of ballast. The non-linear variation of shear strength envelope at a given range of confining pressures is …
Simultaneous Grain Growth And Grain Refinement In Bulk Ultrafine-Grained Copper Under Tensile Deformation At Room Temperature, Hai Liang Yu, Cheng Lu, Anh Kiet Tieu, Hui Jun Li, Ajit R. Godbole, Charlie Kong, Xing Zhao
Simultaneous Grain Growth And Grain Refinement In Bulk Ultrafine-Grained Copper Under Tensile Deformation At Room Temperature, Hai Liang Yu, Cheng Lu, Anh Kiet Tieu, Hui Jun Li, Ajit R. Godbole, Charlie Kong, Xing Zhao
Faculty of Engineering and Information Sciences - Papers: Part A
Grain growth and grain refinement behavior during deformation determine the strength and ductility of ultrafine-grained materials. We used asymmetric cryorolling to fabricate ultrafine-grained copper sheets with an average grain width of 230 nm and having a laminate structure. The sheets show a high-true failure strain of 1.5. Observation of the microstructure at the fracture surface reveals that ultrafine laminate-structured grains were simultaneously transformed into both equiaxed nanograins and coarse grains under tensile deformation at room temperature.
Implications Of Ballast Degradation Under Cyclic Loading, Sanjay Nimbalkar, Buddhima Indraratna
Implications Of Ballast Degradation Under Cyclic Loading, Sanjay Nimbalkar, Buddhima Indraratna
Faculty of Engineering and Information Sciences - Papers: Part A
In spite of recent advances in track geotechnology, the understanding of the mechanisms of ballast degradation is vital for improved design to withstand high speed cyclic loading. The research conducted at Centre for Geomechanics and Railway Engineering (CGRE) at University of Wollongong (UOW) has shown that ballast degradation is influenced by various factors including the amplitude, frequency, number of load cycles, particle size distribution, confining pressure, angularity and fracture strength of individual grains. A series of cyclic drained triaxial tests were conducted using a largescale cylindrical apparatus designed and built at UOW for frequencies ranging from 10-40 Hz. A low …
Effect Of Temperature On Microstructure And Deformation Mechanism Of Fe-30mn-3si-4al Twip Steel At Strain Rate Of 700 S-1, Zhiping Xiong, Xue-Ping Ren, Jian Shu, Zhe-Lei Wang, Wei-Ping Bao, Shu-Xia Li
Effect Of Temperature On Microstructure And Deformation Mechanism Of Fe-30mn-3si-4al Twip Steel At Strain Rate Of 700 S-1, Zhiping Xiong, Xue-Ping Ren, Jian Shu, Zhe-Lei Wang, Wei-Ping Bao, Shu-Xia Li
Faculty of Engineering and Information Sciences - Papers: Part A
As twinning-induced plasticity (TWIP) steel is one potential material for shaped charge liner due to the combination of high strength and high plasticity, deformation mechanism at high strain rate and high temperature is required to study. Compression experiments of Fe-30Mn-3Si-4Al TWIP steel were conducted using a Gleeble-1500 thermal simulation machine and a split-Hopkinson pressure bar (SHPB) between 298 and 1073 K at strain rates of 10-3 and 700 s-1, respectively. Microstructures were observed using optical microscopy (OM) and transmission electron microscopy (TEM). Results show that flow stress and densities of deformation twins and dislocations decrease with increasing deformation temperature at …
Interface Analysis And Hot Deformation Behaviour Of A Novel Laminated Composite With High-Cr Cast Iron And Low Carbon Steel Prepared By Hot Compression Bonding, Zhengyi Jiang, Xingjian Gao, Sheng-Li Li, Hong Mei Zhang, Dengfu Chen, Jian Zhong Xu
Interface Analysis And Hot Deformation Behaviour Of A Novel Laminated Composite With High-Cr Cast Iron And Low Carbon Steel Prepared By Hot Compression Bonding, Zhengyi Jiang, Xingjian Gao, Sheng-Li Li, Hong Mei Zhang, Dengfu Chen, Jian Zhong Xu
Faculty of Engineering and Information Sciences - Papers: Part A
A hot compression bonding process was developed to prepare a novel laminated composite consisting of high-Cr cast iron (HCCI) as the inner layer and low carbon steel (LCS) as the outer layers on a Gleeble 3500 thermomechanical simulator at a temperature of 950 °C and a strain rate of 0.001 S-1. Interfacial bond quality and hot deformation behaviour of the laminate were studied by microstructural characterisation and mechanical tests. Experimental results show that the metallurgical bond between the constituent metals was achieved under the proposed bonding conditions without discernible defects and the formation of interlayer or intermetallic layer …
Coupled Discrete Element-Finite Difference Method For Analysing The Load-Deformation Behaviour Of A Single Stone Column In Soft Soil, Buddhima Indraratna, Ngoc Trung Ngo, Cholachat Rujikiatkamjorn, Scott W. Sloan
Coupled Discrete Element-Finite Difference Method For Analysing The Load-Deformation Behaviour Of A Single Stone Column In Soft Soil, Buddhima Indraratna, Ngoc Trung Ngo, Cholachat Rujikiatkamjorn, Scott W. Sloan
Faculty of Engineering and Information Sciences - Papers: Part A
Experimental studies and numerical modelling of the deformation of soft clay stabilised by stone columns have been conducted over the past few decades. Continuum-based numerical models have provided valuable insight into the prediction of settlement, lateral deformation, and stress and strain-rate dependent behaviour of stone columns at a macroscopic scale, but because they consist of granular material such as crushed rock, gravel, and waste rock aggregates, their behaviour is influenced by inter-particle micromechanics and cannot be modelled properly using these models. In this paper a novel coupled model of the discrete element method (DEM) and finite difference method (FDM) is …
Oxide Scale Characterization Of Ferritic Stainless Steel And Its Deformation And Friction In Hot Rolling, Xiawei Cheng, Zhengyi Jiang, Dongbin Wei, Liang Hao, Jingwei Zhao, Laizhu Jiang
Oxide Scale Characterization Of Ferritic Stainless Steel And Its Deformation And Friction In Hot Rolling, Xiawei Cheng, Zhengyi Jiang, Dongbin Wei, Liang Hao, Jingwei Zhao, Laizhu Jiang
Faculty of Engineering and Information Sciences - Papers: Part A
The oxidation kinetics of ferritic stainless steel 430 was studied in dry and humid air at 1090 °C by Thermo Gravimetric Analysis (TGA). Different atmospheres and heating times were adopted for reheating to obtain different compositions and thickness of the oxide scale. Hot rolling was performed on a 2-high Hille 100 experimental rolling mill at various reductions. Oxide scale thickness and composition were analysed with optical microscopy (OM), scanning electron microscope (SEM) and X-ray diffraction (XRD). The surface profiles were examined by a digital microscope, and the topographic features of the thin oxide scale surface were examined with an atomic …
Thermal Stability And Properties Of Deformation-Processed Cu-Fe In Situ Composites, Keming Liu, Zhengyi Jiang, Jingwei Zhao, Jin Zou, Lei Lu, Deping Lu
Thermal Stability And Properties Of Deformation-Processed Cu-Fe In Situ Composites, Keming Liu, Zhengyi Jiang, Jingwei Zhao, Jin Zou, Lei Lu, Deping Lu
Faculty of Engineering and Information Sciences - Papers: Part A
This paper investigated the thermal stability, tensile strength, and conductivity of deformation-processed Cu-14Fe in situ composites produced by thermo-mechanical processing. The thermal stability was analyzed using scanning electronic microscope and transmission electron microscope. The tensile strength and conductivity were evaluated using tensile-testing machine and micro-ohmmeter, respectively. The Fe fibers in the deformation-processed Cu-14Fe in situ composites undergo edge recession, longitudinal splitting, cylinderization, break-up, and spheroidization during the heat treatment. The Cu matrix experiences recovery, recrystallization, and precipitation phase transition. The tensile strength and conductivity first increase with increasing temperature of heat treatment, reach peak values at different temperatures, and then …
Effect Of Extreme Pressure Additives On The Deformation Behavior Of Oxide Scale During The Hot Rolling Of Ferritic Stainless Steel Strips, Liang Hao, Zhengyi Jiang, Xiawei Cheng, Jingwei Zhao, Dongbin Wei, Laizhu Jiang, Suzhen Luo, Ming Luo, Li Ma
Effect Of Extreme Pressure Additives On The Deformation Behavior Of Oxide Scale During The Hot Rolling Of Ferritic Stainless Steel Strips, Liang Hao, Zhengyi Jiang, Xiawei Cheng, Jingwei Zhao, Dongbin Wei, Laizhu Jiang, Suzhen Luo, Ming Luo, Li Ma
Faculty of Engineering and Information Sciences - Papers: Part A
High-speed steel (HSS) materials are universally used as work rolls for the hot rolling of stainless steels. Their use has increased the output of the rolling mill and decreased roll material consumption and grinding. Sticking defects often occur, however, during the hot rolling process. In this article, extreme pressure (EP) additives were dropped on the HSS samples at high temperature. Zinc dialkyl dithiophosphate (ZDDP) was chosen as the most effective EP additive by scratch tests on the HSS samples. In order to determine the optimum proportion of ZDDP in the lubricant, two reduction rates were tested on a Hille 100 …
Recent Advances In Railroad Infrastructure And Track Performance - Australian Experience, Buddhima Indraratna, Sanjay Nimbalkar
Recent Advances In Railroad Infrastructure And Track Performance - Australian Experience, Buddhima Indraratna, Sanjay Nimbalkar
Faculty of Engineering and Information Sciences - Papers: Part A
As trains become longer, heavier and quicker, ballast shows signs of distress and degradation, leading to deterioration of the track geometry. Appropriate stabilisation techniques using artificial inclusions such as polymeric geosynthetics and energy-absorbing shock mats are needed to improve track stability and longevity. Large-scale laboratory tests at University of Wollongong revealed that the geogrids with an optimum aperture governed the effectiveness of the reinforcement mechanism. The use of shock mats was influenced by their placement position and the type of subgrade (e.g. estuarine soil, rock etc.). In these studies, different types of geosynthetics and shock mats were placed beneath the …
Deformation Of Coal Fouled Ballast Stabilized With Geogrid Under Cyclic Load, Buddhima Indraratna, Ngoc Trung Ngo, Cholachat Rujikiatkamjorn
Deformation Of Coal Fouled Ballast Stabilized With Geogrid Under Cyclic Load, Buddhima Indraratna, Ngoc Trung Ngo, Cholachat Rujikiatkamjorn
Buddhima Indraratna
This paper presents the results of laboratory investigations into the deformation of coal fouled ballast stabilized with geogrid at various degrees of fouling. A novel track process simulation apparatus was used to simulate realistic rail track conditions subjected to cyclic loading, and the void contamination index (VCI) was used to evaluate the level of ballast fouling. The experimental results show that coal fines act as a lubricant, causing grains of ballast to displace and rotate, and as a result, accelerate its deformation. However, coal fines also reduce ballast breakage because of a cushioning effect, that is, by reducing interparticle attrition. …
Response Of The Al Σ5 〈001〉 Left {310} Symmetric Tilt Grain Boundary To The Shear Deformation Simulated By Molecular Dynamics, Kuiyu Cheng, Cheng Lu, A Kiet Tieu
Response Of The Al Σ5 〈001〉 Left {310} Symmetric Tilt Grain Boundary To The Shear Deformation Simulated By Molecular Dynamics, Kuiyu Cheng, Cheng Lu, A Kiet Tieu
Faculty of Engineering and Information Sciences - Papers: Part A
In the present study, shear response of the Al [001] symmetrical tilting Σ5 (310) grain boundary (GB) was investigated by a three dimensional bicrystal at 500~750 K. It was found that the GB gradually rotated around the [001] tilt axis during the shear deformation due to the combination of surface strain, GB sliding and GB coupled motion. These rotated grain boundaries were Σ5 asymmetrical or symmetrical tilt grain boundaries and led to the normal stress σxx in the bicrystal system. It was also found that the response of the grain boundary to the shear deformation was closely related to the …
Vacancy-Type Defects Study On Ultra-Fine Grained Aluminium Processed By Severe Plastic Deformation, Li-Jun Su, C Lu, Guanyu Deng, A Kiet Tieu, L C. Zhang, P Guagliardo, S N. Samarin, J F. Williams
Vacancy-Type Defects Study On Ultra-Fine Grained Aluminium Processed By Severe Plastic Deformation, Li-Jun Su, C Lu, Guanyu Deng, A Kiet Tieu, L C. Zhang, P Guagliardo, S N. Samarin, J F. Williams
Faculty of Engineering and Information Sciences - Papers: Part A
Vacancy-type defects play an important role in the metal materials deformed by severe plastic deformation (SPD). The present work use positron annihilation lifetime spectroscopy (PALS) to test the vacancy-type defects in aluminium alloys processed by equal channel angular pressing (ECAP) and accumulative roll bonding (ARB). ECAP at room temperature and cryogenic temperature was conducted to AA1050 and ARB with 200 C preheating was conducted to AA1050 and AA6061 to produce laminated AA1050 sheets, AA6061 sheets and AA1050/AA6061 composites. High fraction of vacancy-type defects were detected in all the deformed samples. Vacancies associated with dislocations and bulk mono-vacancies have been identified …
Deformation Characterization Of Micro Rolling For Stainless Steel Foil, Haibo Xie, Kenichi Manabe, Tsuyoshi Furushima, Kazuo Tada, Zhengyi Jiang
Deformation Characterization Of Micro Rolling For Stainless Steel Foil, Haibo Xie, Kenichi Manabe, Tsuyoshi Furushima, Kazuo Tada, Zhengyi Jiang
Faculty of Engineering and Information Sciences - Papers: Part A
Physical parameters such as microscopic roughness become very important in micro forming process due to increasing surface to volume ratio. As a very important phenomenon in metal forming process, friction size effects are becoming more attracting for researchers because traditional models are not reliable. In this study, the micro rolling deformation characterization has been investigated with SUS 304 stainless steel considering the effect of lubricant, and there exists a sticking area in the contact zone. The evolution of surface roughness and oil film thickness are analyzed. The foil thickness plays an important role in the tribological features of rolling. All …
Molecular Dynamics Simulation On Σ5 Grain Boundaries Of Copper Bicrystal Under Tensile And Shear Deformation, Liang Zhang, Cheng Lu, A Kiet Tieu
Molecular Dynamics Simulation On Σ5 Grain Boundaries Of Copper Bicrystal Under Tensile And Shear Deformation, Liang Zhang, Cheng Lu, A Kiet Tieu
Faculty of Engineering and Information Sciences - Papers: Part A
Molecular Dynamics simulation are employed to investigate the structures and mechanical behavior of both symmetric and asymmetric Σ5[0 0 1] tilt grain boundaries (GBs) of copper bicrystal under uniaxial tension and shear deformation. Simulation results indicate that the Σ5 asymmetric GBs can facet into their corresponding symmetric GB structures. The maximum tensile stress of symmetric GBs is higher than the asymmetric ones at both 10 K and 300 K, which suggests the symmetric GBs may have a more stable boundary structures. All the Σ5 GBs investigate in this study can migrate under the shear deformation with different velocity. The migration …
The Formation Of Complex Microstructures After Different Deformation Modes In Advanced High-Strength Steels, Ilana Timokhina, Elena V. Pereloma, Peter Hodgson
The Formation Of Complex Microstructures After Different Deformation Modes In Advanced High-Strength Steels, Ilana Timokhina, Elena V. Pereloma, Peter Hodgson
Faculty of Engineering and Information Sciences - Papers: Part A
The microstructure of transformation induced plasticity (TRIP) and dual phase (DP) multiphase steels after stamping of an industrial component at different strain levels was investigated using transmission electron microscopy. The TRIP steel microstructure showed a more complex dislocation substructure of ferrite at different strain levels than DP steel. The deformation microstructure of the stamped parts was compared to the deformation microstructure in these complex steels for different "equivalent" tensile strains. It was found that the microstructures are similar only at high levels of strain (>10 pct) for both steels.
Analysis Of Internal Crack Healing Mechanism Under Rolling Deformation, Haitao Gao, Zhengrong Ai, Hailiang Yu, Hongyan Wu, Xianghua Liu
Analysis Of Internal Crack Healing Mechanism Under Rolling Deformation, Haitao Gao, Zhengrong Ai, Hailiang Yu, Hongyan Wu, Xianghua Liu
Faculty of Engineering and Information Sciences - Papers: Part A
A new experimental method, called the 'hole filling method', is proposed to simulate the healing of internal cracks in rolled workpieces. Based on the experimental results, the evolution in the microstructure, in terms of diffusion, nucleation and recrystallisation were used to analyze the crack healing mechanism. We also validated the phenomenon of segmented healing. Internal crack healing involves plastic deformation, heat transfer and an increase in the free energy introduced by the cracks. It is proposed that internal cracks heal better under high plastic deformation followed by slow cooling after rolling. Crack healing is controlled by diffusion of atoms from …
A Study Of Plastic Deformation Behavior During High Pressure Torsion Process By Crystal Plasticity Finite Element Simulation, Peitang Wei, Cheng Lu, A K. Tieu, Guanyu Deng
A Study Of Plastic Deformation Behavior During High Pressure Torsion Process By Crystal Plasticity Finite Element Simulation, Peitang Wei, Cheng Lu, A K. Tieu, Guanyu Deng
Faculty of Engineering and Information Sciences - Papers: Part A
High pressure torsion (HPT) is an efficient technique of producing ultrafine grained materials with exceptional small grain size. In this study, a crystal plasticity finite element method (CPFEM) model has been developed to investigate the plastic deformation behavior of pure aluminum single crystal during the HPT process. The simulation results show that, the distribution and evolution of the macroscopic plastic strain and the accumulative shear strain are similar. The value increases with the increase of the distance from the center as well as the number of revolution. The simulation is capable of reflecting the anisotropic characteristics of HPT deformation, a …
Constitutive Analysis For Hot Deformation Behaviour Of Novel Bimetal Consisting Of Pearlitic Steel And Low Carbon Steel, Xingjian Gao, Zhengyi Jiang, Dongbin Wei, Huijun Li, Sihai Jiao, Jianzhong Xu, Xiaoming Zhang, Jingtao Han, Dengfu Chen
Constitutive Analysis For Hot Deformation Behaviour Of Novel Bimetal Consisting Of Pearlitic Steel And Low Carbon Steel, Xingjian Gao, Zhengyi Jiang, Dongbin Wei, Huijun Li, Sihai Jiao, Jianzhong Xu, Xiaoming Zhang, Jingtao Han, Dengfu Chen
Faculty of Engineering and Information Sciences - Papers: Part A
To understand the high temperature flow behaviour of a novel pearlitic steel (PS) and low carbon steel (LCS) bimetal, hot compression tests in a wide range of temperature and strain rate were conducted on a Gleeble 3500 thermo mechanical simulator, and the constitutive model was developed based on the experimental data. The measured true stress-strain curves exhibited three types of variation patterns, which are (i) a plateau type, (ii) single peak type and (iii) multi peaks type. These patterns well displayed the effects of the deformation temperature, strain rate and plastic strain on the flow behaviour of the bimetal. By …
Crack Healing In A Low-Carbon Steel Under Hot Plastic Deformation, Hailiang Yu, Xianghua Liu, Xinwen Li, Ajit R. Godbole
Crack Healing In A Low-Carbon Steel Under Hot Plastic Deformation, Hailiang Yu, Xianghua Liu, Xinwen Li, Ajit R. Godbole
Faculty of Engineering and Information Sciences - Papers: Part A
The behavior of internal crack healing in low-carbon steel samples undergoing hot plastic deformation was investigated using the MMS 200 thermo-mechanical simulator. The characterization of cracks after plastic deformation was analyzed using scanning electron microscopy under different heating temperatures, reduction ratios, numbers of deformation passes, strain rates, and holding time durations. It was found that the degree of crack healing increases with increasing heating temperature, reduction ratio, and holding time duration, and with decreasing number of deformation passes and strain rate.
Atomistic Simulation Of Tensile Deformation Behavior Of Σ5 Tilt Grain Boundaries In Copper Bicrystal, Liang Zhang, Cheng Lu, A Kiet Tieu
Atomistic Simulation Of Tensile Deformation Behavior Of Σ5 Tilt Grain Boundaries In Copper Bicrystal, Liang Zhang, Cheng Lu, A Kiet Tieu
Faculty of Engineering and Information Sciences - Papers: Part A
Experiments on polycrystalline metallic samples have indicated that Grain boundary (GB) structure can affect many material properties related to fracture and plasticity. In this study, atomistic simulations are employed to investigate the structures and mechanical behavior of both symmetric and asymmetric ∑5[0 0 1] tilt GBs of copper bicrystal. First, the equilibrium GB structures are generated by molecular statics simulation at 0K. The results show that the ∑5 asymmetric GBs with different inclination angles (φ) are composed of only two structural units corresponding to the two ∑5 symmetric GBs. Molecular dynamics simulations are then conducted to investigate the mechanical response …
Effects Of Hydrogen On The Critical Conditions For Dynamic Recrystallization Of Titanium Alloy During Hot Deformation, Jingwei Zhao, Hua Ding, Zhengyi Jiang, Dongbin Wei, Kezhi Linghu
Effects Of Hydrogen On The Critical Conditions For Dynamic Recrystallization Of Titanium Alloy During Hot Deformation, Jingwei Zhao, Hua Ding, Zhengyi Jiang, Dongbin Wei, Kezhi Linghu
Faculty of Engineering and Information Sciences - Papers: Part A
Hot deformation tests were performed to study the flow behavior and microstructural evolution of a Ti600 titanium alloy with different hydrogen contents. The effects of hydrogen on the critical conditions for the initiation of dynamic recrystallization (DRX) were investigated. The DRX kinetics models of hydrogenated Ti600 alloy were developed, and the DRX volume fractions were quantified under different deformation conditions. The results indicate that the addition of proper hydrogen (no greater than 0.3 pct) benefits the decrease of both the critical stress and critical strain for the initiation of DRX. The critical stress and critical strain are dependent linearly on …
Cellular Automaton Simulation Of Hot Deformation Of Trip Steel, Ying Zhi, Xianghua Liu, Hailiang Yu
Cellular Automaton Simulation Of Hot Deformation Of Trip Steel, Ying Zhi, Xianghua Liu, Hailiang Yu
Faculty of Engineering and Information Sciences - Papers: Part A
The recrystallization process of hot deformed austenite of TRIP steel was predicted using Cellular Automaton (CA) combined with the principles of physical metallurgy. A model was developed for prediction of the dynamic and static recrystallization microstructure evolution and properties of hot deformed austenite for TRIP steel. The theoretical modeling of recrystallization was based on dislocation density. The microstructure evolution of austenite recrystallization of TRIP steel (such as the grain shape and size, volume fraction, kinetics curve of recrystallization) was predicted both visually and quantitatively. The distribution and variation of the dislocation density and flow stress were also obtained, and the …
An Experimental Investigation On The Deformation And Degradation Behaviour Of Geogrid-Reinforced Ballast, Sd. K Karimullah Hussaini, B Indraratna, J S. Vinod
An Experimental Investigation On The Deformation And Degradation Behaviour Of Geogrid-Reinforced Ballast, Sd. K Karimullah Hussaini, B Indraratna, J S. Vinod
Faculty of Engineering and Information Sciences - Papers: Part A
Railroad ballast, owing to its unbounded granular nature, spreads laterally when subjected to large vertical axle loads, which influences the track stability. In this view, large-scale cyclic tests have been conducted on ballast to explore the role of geogrid in controlling the lateral deformation of ballast and hence improving the track performance. Fresh latite ballast having a mean particle size of 35 mm and geogrids with different aperture sizes was used for the investigations. Tests were conducted using a modified process simulation test (MPST) apparatus at a loading frequency of 20 Hz, with geogrid placed at the subballast-ballast interface and …
A Deformation Mechanism Of Hard Metal Surrounded By Soft Metal During Roll Forming, Hailiang Yu, A Kiet Tieu, Cheng Lu, Xiong Liu, Ajit Godbole, Huijun Li, Charlie Kong, Q Qin
A Deformation Mechanism Of Hard Metal Surrounded By Soft Metal During Roll Forming, Hailiang Yu, A Kiet Tieu, Cheng Lu, Xiong Liu, Ajit Godbole, Huijun Li, Charlie Kong, Q Qin
Faculty of Engineering and Information Sciences - Papers: Part A
It is interesting to imagine what would happen when a mixture of soft-boiled eggs and stones is deformed together. A foil made of pure Ti is stronger than that made of Cu. When a composite Cu/Ti foil deforms, the harder Ti will penetrate into the softer Cu in the convex shapes according to previously reported results. In this paper, we describe the fabrication of multilayer Cu/Ti foils by the roll bonding technique and report our observations. The experimental results lead us to propose a new deformation mechanism for a hard metal surrounded by a soft metal during rolling of a …