Publications
120 results found
Hu Y, Liu Y, Xi J, et al., 2024, Energy dissipation-based LCF model for additive manufactured alloys with dispersed fatigue properties, Engineering Failure Analysis, Vol: 159, ISSN: 1350-6307
The low-cycle fatigue properties of selective additively manufactured (AM) laser melt (SLM) Ti-6Al-4V alloys using different sintering rates, deposition direction and post-treatment are assessed. The results show that the shape difference among stable hysteresis loops is closely related to the fatigue life and energy dissipation critical value. Additionally, the relationship between the plastic strain energy and plastic strain shows a strong linear correlation in log-log coordinate. Based on the plastic strain energy dissipation process, an energy dissipation-based model is established to predict low cycle fatigue life in the candidate AM alloy. Fatigue life results from the proposed model shows an improvement in the accuracy of the predictions with the experiment and narrows the scatter/error band when compared to the Manson-Coffin, plastic strain energy and the total plastic strain energy models. The proposed model is applied to the AM TiAl alloy to overcome the drawback of the wider scatter in fatigue life predictions caused by dispersion of fatigue properties found in this mode of manufacture.
Wang W, Zhang R, Shirzadi AA, et al., 2024, Thermal cracking: Clarifying the effects of phases, voids and grains through characterisation and crystal plasticity modelling, Journal of the Mechanics and Physics of Solids, Vol: 186, ISSN: 0022-5096
Thermally-induced cracking typically occurs during the cooling stage of various manufacturing processes, and is commonly seen in multiphase or the joints of dissimilar materials due to mismatch in their thermo-mechanical properties, such as thermal expansion, elastic-plastic deformation and, in some cases, phase transformation. However, the underlying cracking mechanism associated with local microstructure is still elusive. To improve the mechanistic understanding of thermal cracking, this work uses the diffusion-bonded 9Cr-1Mo steel as an example to study the key microstructural variables, such as interfacial phases, voids, grain boundary migration and crystallographic orientations. Meanwhile, a temperature-dependent crystal plasticity model coupled with a cohesive zone model is developed to provide more insights into the thermal-induced stress distribution at the grain scale. It is found that the stress at the void-free boundary of martensite and ferrite is dominated by shear, and its magnitude is insufficient to nucleate cracks. Whereas voids at phase boundaries can induce significant tensile stress, resulting in cracking at the phase boundaries as well as diffusion-bonded interfaces. Also, the occurrence of interfacial grain boundary migration plays an important role in local stress distribution. These microstructure features and their evolution are experimentally observed and used to verify the developed crystal plasticity models. These findings enhance the understanding of the influence of microstructure features on thermal cracking and provide a guide to designing and fabricating the microstructure with improved thermal crack resistance in various manufacturing processes.
Wang W, Chan CK, Wang Y, et al., 2024, Fabricating carbon steel/Ti composites through forge-welding via in-situ interfacial reaction of Ni coating, Materials Science and Engineering: A, Vol: 893, ISSN: 0921-5093
Solid-state bonding is paramount in joining dissimilar materials, often combined with metal forming, such as forging, rolling and extrusion, to fabricate composites with a designed structure. Owing to its superior mechanical properties and low density, the carbon steel/Ti composite structure is attractive in automotive and aerospace industries but is difficult to fabricate due to the decarburization of carbon steel's faying surface. In this work, a carbon steel/Ti6Al4V composite structure was first fabricated via a forge-bonding method with the assistance of a Ni coating layer. Results show that the Ni layer on the faying surfaces precludes the decarburization of the steel and the growth of the TiC phase so as to improve the bonding quality. Meanwhile, the in-situ eutectic reaction between the Ni layer and β-Ti was observed. As a result, a seamless bonded interface with the total elimination of the Ni layer can be obtained. The bonding strength was examined to establish the relationship between bonding windows, microstructure and the resulting mechanical properties. An experimentally validated thermal-mechanical finite element model was also developed to understand the process-dependent interface evolution. This work opens a new avenue for fabricating carbon steel/Ti6Al4V composite, extending the flexibility of achieving complex structures by combining solid-state bonding with other metal-forming technologies.
Zhang K, Jiang J, 2024, Effects of grain size and temperature on slip and twinning activity in a magnesium-rare earth alloy, Materials Science and Engineering: A, Vol: 891, ISSN: 0921-5093
Understanding the deformation mechanisms in magnesium alloys is critical to develop the next-generation high-performance magnesium alloys. In this work, the effects of grain size and temperature on slip and twinning activities in WE43 magnesium-rare earth alloy were investigated with the quasi-in-situ electron backscattering diffraction method and slip trace analysis. Compression tests were conducted for the samples with three different grain sizes at room temperature (RT) and liquid nitrogen temperature (LNT), respectively. More pyramidal slips were activated in the fine-grained sample to accommodate the plastic strain instead of more twins generated in the coarse-grained sample, which contributed to its higher strain to failure and strain hardening rate. Numerous individual twins with thin structures formed in the fine-grained sample, while thick twins were observed in the coarse-grained sample. The numerous thin twins and high activities of pyramidal slips in the fine-grained sample would be attributed to the high kernel average misorientation (KAM) value and local stress concentration around grain boundaries. Regarding temperature effects, more thin twins and twin-twin interactions were observed at LNT than at RT, and the KAM value was high around these twin boundaries, which contributed to enhancing the flow stress but reducing the strain to failure at LNT.
Wang Y, Liu Y, Jiang J, 2024, Temperature Effect in the Nickel-Superalloy Forming Process by Solid-State Bonding, Pages: 221-228, ISSN: 2195-4356
For those large-size components used in oil, chemical, aerospace, or nuclear industries, a novel solid-state additive manufacturing(AM) by piling up and bonding pre-shaped thick plate layers appears as a potential technology [1]. Apart from high efficiency and lower materials wastage, solid-state AM can avoid some solidification defects in traditional AM, like hot cracks and dendritic microstructure. The sound bonding between layers is achieved by hot-deformation method. The combination of high temperature and large plastic deformation would lead to severe microstructure evolution and break-up of the oxide films, which facilitates the full recovery of the joint performance to base level. For this new manufacturing method, the quality of the bonded interface and its dependence on the deformation condition would be the key focus. In this work, the effects of temperature on the bonding quality is investigated with IN718 samples using Gleeble. The tensile results of the bonded samples show comparable properties with the references.
Huang Y, Jiang J, 2024, Experimental and Crystallographic Studies of Pyramidal <c+a> Slip in Magnesium, Pages: 429-436, ISSN: 2195-4356
Constraint uniaxial compression of magnesium single crystals along c-axis was carried out at room temperature and elevated temperatures of up to 500 ℃. The deformation structures were characterized by electron backscatter diffraction (EBSD). The results showed no evidence of pyramidal <c+a> slip and twinning was responsible for plastic deformation in the range of temperatures tested. The atomic configurations and crystallographic features associated with pyramidal <c+a> dislocations were revealed with the help of CrystalMaker software and a possible <c+a> dislocation core structures was reconstructed. The crystallographic analysis suggested that pyramidal slip was difficult because <c+a> dislocations would involve too many atoms on irrational lattice planes and directions.
Wang Y, Tan Z, Wang W, et al., 2023, Development of a solid-state extrusion-roll-bonding based additive manufacturing (ERB-AM) technology for aluminum alloys, Additive Manufacturing, Vol: 78
To solve the poor printability issue of high-performance aluminum alloys in additive manufacturing processes, a solid-state hybrid additive manufacturing (AM) technology, combining extrusion and roll bonding operations, is proposed, in which the extruded aluminum layers are soundly bonded through the hot-rolling operation. In this feasibility and early-stage research, a lab-scale extrusion-roll-bonding prototype machine is designed and built. Aluminum alloy, AA1060, owing to its relatively low loading requirements for the prototype, is used for the proof of the concept. The extrusion-roll-bonding tests have been undertaken at different temperatures and rolling reductions to identify optimal processing parameters. The corresponding bonding quality was estimated using an optical microscope (OM). Also, miniature AM tensile samples were tested to evaluate the tensile properties of the bonding interfaces. It is of great interest to see that the AM material did not fracture at the bonding interface and its stress-strain response is similar to that of the original material. In-depth analyses on the interfacial grain and oxide distribution and their effects on the interfacial strength were undertaken using a transmission electron microscope (TEM) and scanning electron microscope (SEM)/electron backscatter diffraction (EBSD). This study demonstrates the proposed solid-state AM technique can successfully manufacture aluminum alloys at their solid states, achieving comparable mechanical properties to their wrought states. This new solid state AM technique may enable a wide range of alloys with poor printability to be used in various industries to produce safety-critical and large, structural components with simple geometry.
Zhang K, Shao Z, Robson J, et al., 2023, Achieving high ductility and strength in magnesium alloy through cryogenic-hot forming, Journal of Magnesium and Alloys, Vol: 11, Pages: 3130-3140, ISSN: 2213-9567
Magnesium alloys are the lightest structural alloys and have attracted substantial research attention in the past two decades. However, their mechanical properties, including ductility and strength, are limited after forming due to the formation of coarse grains and strong texture. This study proposes and proves a new cryogenic-hot forming process concept. Cryogenic deformation is imposed before the hot deformation. The effect of the cryogenic step has been compared with a conventional direct hot deformation process. The mechanical properties, microstructure, and texture of both the novel and conventional process routes have been compared. The cryogenic-hot deformed sample exhibits the highest ductility and fracture strength (ultimate tensile strength: 321 MPa, ductility: 21%) due to effective grain refinement and texture weakening by cryogenically formed twin-twin interaction induced recrystallisation. The proposed cryogenic-hot forming process can be a potential innovative manufacturing method for producing high-performance magnesium components.
Zhang R, Jiang J, Lin J, et al., 2023, Investigation of variability in apparent values of materials properties in thermo-mechanical uniaxial tensile tests on sheet metals, Journal of Manufacturing Processes, Vol: 101, Pages: 737-754, ISSN: 1526-6125
Thermo-mechanical uniaxial tensile testing is commonly carried out to characterise the mechanical properties of materials under conditions which mimic advanced industrial forming processes, such as hot stamping of steels and aluminium alloys, and to generate microstructures for metallographic investigation. However, in this type of testing, heat loss to the specimen grips can lead to nonuniform temperature distributions along the gauge length, resulting in challenges in determining absolute values of materials properties at the nominal temperature of interest. The present study investigates the effect of these nonuniform temperature distributions on the variability in the thermo-mechanical properties as measured in the tests, and in the microstructures of the tested specimens. For this purpose, uniaxial tensile tests on the boron steel 22MnB5 and aluminium alloy AA6082 were performed under hot stamping conditions using a Gleeble 3800 thermal-mechanical physical simulation system, in which the specimens were heated using resistance heating and the strain fields were measured using digital image correlation (DIC). The nonuniformity of the temperature distributions along the gauge length was quantified. Both the strains and the strain rates along the gauge length were then computed and the effects of factors such as pre-forming gauge length, post-forming gauge length and specimen design on the spatial distribution of strains and strain rates were investigated. The effects of these factors on the values of thermo-mechanical properties determined from the tests, such as the ductility and the ultimate tensile strength (UTS), were also analysed and quantified. This study reveals the variability in the apparent values of materials properties as determined by thermo-mechanical testing resulting from nonuniform temperature distributions, and provides experimental data for the development of new standards for thermo-mechanical tests in future.
Wang W, Balint DS, Shirzadi AA, et al., 2023, Imparted benefits on mechanical properties by achieving grain boundary migration across voids, Acta Materialia, Vol: 256, Pages: 1-12, ISSN: 1359-6454
Understanding the interaction of micro-voids and grain boundaries is critical to achieving superior mechanical properties for safety-critical parts. Micro-voids and grain boundaries may interact during advanced manufacturing processes such as sintering, additive manufacturing and diffusion bonding. Here, we show imparted benefits on mechanical properties by achieving grain boundary migration across voids. The micro-mechanisms and quantitative analysis of grain boundary migration on local deformation were studied by integrated in-situ EBSD/FSE and crystal plasticity finite element modelling. It is revealed that a migrated grain boundary does not alter the activated slip systems but precludes grain boundary-multislip interaction around interfacial voids to alleviate stress concentrations. The stress mitigation caused by grain boundary migration is almost the same as that caused by void closure under the example diffusion bonding thermal-mechanical process used in this study. This new understanding sheds light on the mechanistic link between GND hardening, grain boundary migration and the corresponding material tensile behaviour. It opens a new avenue for achieving superior mechanical properties for metallic parts with micro-defects such as those generated in diffusion-bonded, sintered and additive manufactured components.
Wu G, Tan X, Yuan M, et al., 2023, High thermoelectric and mechanical performance in strong-textured n-type Bi2Te2.7Se0.3 by temperature gradient method, CHEMICAL ENGINEERING JOURNAL, Vol: 470, ISSN: 1385-8947
Li Y, Liu Y, Luo Z, et al., 2023, Ce/Mn/Cr: Y3Al5O12 phosphor ceramics for white LED and LD lighting with a high color rendering index, CERAMICS INTERNATIONAL, Vol: 49, Pages: 24703-24711, ISSN: 0272-8842
Yan Z, Yi L, Xu H, et al., 2023, Interfacial thermal stresses of segmented thermoelectric generators, JOURNAL OF THERMAL STRESSES, Vol: 46, Pages: 574-587, ISSN: 0149-5739
Wu X, Luo Z, Zhuang Y, et al., 2023, The co-optimization of efficiency and emission bandwidth in GSAGG:Cr3+NIR ceramic phosphors, CERAMICS INTERNATIONAL, Vol: 49, Pages: 21688-21694, ISSN: 0272-8842
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Jin C, Li R, Liu Y, et al., 2023, High-performance Gd3Al4GaO12:Cr3+phosphors for next-generation far-red LEDs, MATERIALS RESEARCH BULLETIN, Vol: 163, ISSN: 0025-5408
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- Citations: 2
Zhang K, Jiang J, 2023, Enhancement of plasticity in Mg-3Al-1Zn alloy at cryogenic temperature, Journal of Materials Research and Technology, Vol: 25, Pages: 7454-7459, ISSN: 2238-7854
Compression tests were conducted at room and cryogenic temperatures to investigate the lowtemperature plasticity in Mg-3Al-1Zn alloy. The strain to failure and fracture strength in Mg3Al-1Zn alloy increase by 21.4% and 51.6% from room to cryogenic temperature. Using aquasi-in-situ EBSD method, it is found that {10 1̅ 2} tension twins dominate at roomtemperature, while abundant (101̅2)-(011̅2) twin-twin interactions are observed at cryogenictemperature. Multiple slips, including pyramidal and basal slips, occur in twin-twin interactions,enhancing the strain to failure and flow stress at cryogenic temperature. The high dislocationdensity near twin-twin interactions boundaries would contribute to the high hardening rate andflow stress at cryogenic temperature. This work would provide a novel way to enhanceplasticity in magnesium alloys and gain an in-depth understanding of twin-twin interactions.
Jin C, Li R, Liu Y, et al., 2023, Efficient and Stable Gd<sub>3</sub>Ga<sub>5</sub>O<sub>12</sub>:Cr<SUP>3+</SUP> Phosphors for High-Performance NIR LEDs, ADVANCED OPTICAL MATERIALS, ISSN: 2195-1071
Xiao D, Sun P, Wu J, et al., 2023, Thermoelectric Generator Design and Characterization for Industrial Pipe Waste Heat Recovery, PROCESSES, Vol: 11
Sun F, Penchev P, Pruncu CI, et al., 2023, On enhancement of fracture resistance of adhesive joints by surface micropatterning using a femtosecond laser, Journal of Materials Processing Technology, Vol: 315, Pages: 1-12, ISSN: 0924-0136
This study focuses on the influence of surface micropatterns, including uniform and nonuniform grooves fabricated by selective removal of a designed volume from aluminum alloy substrates using a femtosecond laser, on the mode I fracture behavior of adhesively bonded interfaces. The morphology, wettability, chemistry and microstructure of the patterned surfaces have been analyzed. The mode I fracture behavior of adhesive joints was characterized by measuring the fracture resistance using a J-integral approach, and the fracture process in the joint was investigated numerically using a continuum damage model. The results show that the laser patterning has modified the surface roughness, wettability and surface chemistry such that the fracture resistance could be greatly increased. It also reveals the significance of patterning uniformity across the surfaces and the existence of a limiting effective patterning ratio (the ratio of the patterned area to the flat bonding area) on enhancing the fracture resistance. Local plastic deformation that occurred in the adhesive at the patterned structures due to stress concentration was found to be one toughening mechanism although it tended to induce crack growth close to one substrate-adhesive interface.
Wei Q, Qu C, Jiang J, et al., 2023, The effect of EDTA solution on corneal endothelial cells in rabbits, HELIYON, Vol: 9
Zhang Q, Yuan M, Pang K, et al., 2023, High-Performance Industrial-Grade p-Type (Bi,Sb)<sub>2</sub>Te<sub>3</sub> Thermoelectric Enabled by a Stepwise Optimization Strategy, ADVANCED MATERIALS, Vol: 35, ISSN: 0935-9648
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- Citations: 2
Wang R, Cai J, Zhang Q, et al., 2023, Mismatched atomic bonds and ultralow thermal conductivity in Ag-based ternary chalcopyrites, PHYSICAL REVIEW B, Vol: 107, ISSN: 2469-9950
Zhang X, Cai J, Tan X, et al., 2023, Improved thermoelectric properties in n-type polycrystalline SnSe<sub>0.95</sub> by PbCl<sub>2</sub> doping, MATERIALS ADVANCES, Vol: 4, Pages: 1372-1377
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- Citations: 1
Yi L, Xu H, Yang H, et al., 2023, Design of Bi2Te3-based thermoelectric generator in a widely applicable system, JOURNAL OF POWER SOURCES, Vol: 559, ISSN: 0378-7753
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Huang W, Tan X, Cai J, et al., 2023, Synergistic effects improve thermoelectric properties of zone-melted n-type Bi<sub>2</sub>Te<sub>2</sub>.7Se<sub>0.3</sub>, MATERIALS TODAY PHYSICS, Vol: 32, ISSN: 2542-5293
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Wang X, Wu G, Wang R, et al., 2023, Synergistic optimizing thermoelectric performance of SnTe by the integrated Multi-strategy, CHEMICAL ENGINEERING JOURNAL, Vol: 453, ISSN: 1385-8947
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Huang Y, Jiang J, 2023, A Critical Review of von Mises Criterion for Compatible Deformation of Polycrystalline Materials, CRYSTALS, Vol: 13
Zhou X, Jiang J, Hu Z, et al., 2022, Lightweight Materials in Electric Vehicles, International Journal of Automotive Manufacturing and Materials, Pages: 3-3
<jats:p>ReviewLightweight Materials in Electric VehiclesXianyan Zhou 1,*, Jun Jiang 2, Zhili Hu 3, and Lin Hua 31 Department of Mechanical and Industrial Engineering, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, Norway 2 Department of Mechanical Engineering, Imperial College London, Exhibition Road, London, SW7 2AZ, UK3 School of Automotive Engineering, Wuhan University of Technology, Luoshi Road, Wuhan, 430070, China* Correspondence: xianyan.zhou@ntnu.no Received: 23 September 2022Accepted: 21 November 2022Published: 18 December 2022 Abstract: Lightweight materials are highly demanded in electric vehicles (EVs) to reduce environmental impacts and energy consumption. Aluminium alloys are promising materials in EVs due to their advantages such as high specific strength, corrosion resistance and recyclability. However, forming complex-shaped thin-wall aluminium products is challenging due to their poor formability and limited dimensional accuracy. Meanwhile, recycling some of the high-strength aluminium alloys from EVs is still challenging. This review highlights some of the future potential aluminium forming techniques for EV production, including incremental sheet forming (ISF), hot forming and quenching (HFQ ® ) technique, and transverse stretching and local bending (TSLB). Also, the issues associated with aluminium recycling are listed and discussed. This review provides scientific guidance to the industry and the scientific community for advancing the applications of aluminium alloys in EVs.</jats:p>
Liu Y, Zhang C, Wang Y, et al., 2022, Reveal the hot deformation behaviour and microstructure evolution in additively manufactured 316L stainless steel, Materials Science and Engineering: A, Vol: 861, Pages: 1-11, ISSN: 0921-5093
The novel hybrid manufacturing process incorporating additive manufacturing (AM) with a subsequent hot compression process has been proposed and applied to 316L stainless steel (316L SS). Compared to the conventional wrought 316L SS, the significantly coarser grain size was characterized in the directly AMed specimen, resulting in unacceptable mechanical properties as safety-critical parts. These coarse grains can be refined through the subsequent hot compression process. However, the detailed grain refinement process in these AMed materials has not been exploited. This motivates the study of the grain refinement of AM specimens through dynamic recrystallization (DRX) in hot compression. Hot compression was applied on AMed 316L SS specimens at temperatures from 800 °C to 1000 °C and different strain rates of 0.01 s−1, 0.1 s−1 and 1 s−1 by Gleeble. The results were compared with conventional wrought-annealed 316L SS specimens. To explain the flow stress behaviour, the underlying grain size, orientations, morphologies, and geometrically necessary dislocation (GND) density distribution and evolution were characterized by the electron backscatter diffraction (EBSD). The results suggest that the initial microstructure difference plays a dominant role in the flow stress response, and the DRX behaves very differently in these AMed and wrought-annealed specimens.
Jiang J, Lu Q, Zhang C, et al., 2022, Reveal the viscoplastic behaviour and microstructure evolution of stainless steel 316L, Materials, Vol: 15, ISSN: 1996-1944
Stainless steel 316L is a widely used structural material in the nuclear industry because of its excellent corrosion resistance and mechanical properties. However, very little research can be found on its viscoplastic behaviour and microstructure evolution at warm and hot deformation conditions, which hinder the possible application of advanced manufacturing technologies for producing complex parts, such as superplastic forming or hydroforming. The aims of this study are to explore stainless steel 316L’s viscoplastic behaviour, to determine its strain rate sensitivities, and to reveal its underlying microstructure evolution; this will allow appropriate manufacturing (forming) technologies and the optimal forming condition to be determined. Hence, isothermal tensile tests at 700 °C, 800 °C, 900 °C, and 1000 °C at strain rates of 0.01 s−1 and 0.001 s−1 have been conducted. Moreover, the corresponding microstructure evolution, including the grain orientation and geometrically necessary dislocation density, has been revealed by the electron backscatter diffraction method. The data show the viscoplastic behaviour of stainless steel 316L under various thermomechanical deformation conditions and how microstructure evolution influences the viscoplastic flow stress.
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