► Al 7075 alloy has been cryorolled to obtain ultrafine grained microstructure. ► Cryorolled Al 7075 alloy samples exhibit higher strength and hardness. ► Grain size effect and dislocation density ...enhances mechanical properties.
High strength age hardenable Al 7XXX series alloys are difficult to process by many of the severe plastic deformation processes at room temperature. The Al 7075 alloy has been processed at cryogenic temperature and room temperature up to different rolling strains, in the present work, with the objective of developing a processing strategy to obtain ultrafine grained microstructure with enhanced mechanical properties in the alloy. It has been identified that the Al 7075 alloy samples can be successfully cryorolled to higher strains (up to 3.4) if the reduction per pass is less than 0.3
mm, however it was found to be difficult to deform the samples at room temperature. A cryorolling strain of 3.4 has been found to be desirable for producing the ultrafine grained Al 7075 alloys with the high angle grain boundaries. However, the subgrains are not recrystallized up to this strain in the case of room temperature rolled Al alloys. The strength and hardness of the cryorolled Al 7075 alloy samples are higher than that of the room temperature rolled samples as observed in the present work. The improved strength and hardness of cryorolled samples are due to the grain size effect and higher dislocation density. The reduction in dimple size of cryorolled Al 7075 alloy upon failure confirms the grain refinement and strain hardening mechanism operating in the heavily deformed samples.
•MATLAB based XFEM codes has been developed to analyze FCGR of Additively manufactured Ti alloy.•The XFEM model could predict FCGR in differently cracked samples under mode I and mixed-mode ...loading.•The modified XFEM implemented through Abaqus model could elucidate the fracture toughness of Ti alloy.•The XFEM model is used to predict the tensile and fracture behavior of Ti alloy.
The mechanical properties such as tensile, fracture toughness, and fatigue properties of Additive Manufacturing (AM) fabricated Ti6Al4V alloy is critically crucial for structural applications. The in-house developed MATLAB-based extended finite elements method (XFEM) model has been utilized to analyse experimental results of fatigue, fracture, and tensile properties of AM fabricated Ti6Al4V alloy, to avoid expensive and destructive mechanical characterisation. The XFEM model was first used to validate the single edge cracked sample of laser powder bed fusion (LPBF) processed Ti6Al4V alloy for fatigue crack growth rate (FCGR). The XFEM simulation study was further extended to analyse fatigue life of center and double-side cracked specimens, as well as for evaluating fracture toughness KIC upon accounting potential crack initiation site. The model has also been developed to predict FCGR of edge cracked specimen under mixed-mode loading conditions. The critical stress intensity factor (SIF) and stress distribution map in the crack vicinity of the C(T) specimen were modelled through FEA Abaqus package to estimate the fracture toughness of Ti alloy. A similar XFEM approach was used to analyse the tensile properties of Ti alloy to predict its fracture behaviour through the center cracked specimen taken at the tensile gauge section. The strengthening mechanisms contributing to Ti alloy's static and dynamic properties are elucidated through microstructural characteristics of LPBF processed Ti6Al4V alloy reported in the literature.
► Ageing effect on mechanical properties of cryorolled Al 7075 alloy is studied. ► Low temperature ageing at 100
°C for 45
h is the optimum processing conditions. ► Improved tensile strength and ...tensile ductility are observed for ufg Al 7075 alloy.
The effect of ageing on mechanical properties and microstructural characteristics of a precipitation hardenable Al 7075 alloy subjected to rolling at liquid nitrogen temperature and room temperature are has been investigated in the present work employing hardness measurements, tensile test, XRD, DSC, and TEM. The solution-treated bulk Al 7075 alloy was subjected to cryorolling and room temperature rolling to refine grain structures and subsequently ageing treatment to simultaneously improve the strength and ductility. The solution treatment combined with cryorolling up to a true rolling strain of 2.3 followed by low temperature ageing at 100
°C for 45
h has been found to be the optimum processing condition to obtain fine grained microstructure with improved tensile strength (642
MPa) and good tensile ductility (9.5%) in the Al 7075 alloy. The combined effect of suppression of dynamic recovery, partial grain refinement, partial recovery, solid solution strengthening, dislocation hardening, and precipitation hardening are responsible for the significant improvement strength–ductility combination in the cryorolled Al 7075 alloy subjected to peak ageing treatment. The cryorolled and room temperature rolled Al 7075 alloy, upon subjecting to peak ageing treatment, have shown higher strength and ductility in the former than the latter. It is due to presence of high density of nanosized precipitates in the peak aged cryorolled sample.
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▶ The work hardening rates of CR samples follows the trend as: ST
>
OA
>
PA. ▶ The strengthening effect of CR
+
PA samples follows the trend as: ST
>
PA
>
OA. ▶ The work hardening ...rate of PA samples saturates at a CR strain of 2.3. ▶ The work hardening rate of ST samples is not saturated at a CR strain of 2.3. ▶ ST samples after CR shows higher fraction of HAGB than that of PA and OA samples.
The effect of solutes, coarse and fine precipitates on work hardening rate and microstructure refinement of cryorolled Al 6063 alloy at different strains was investigated by employing hardness measurements, tensile tests, DSC, XRD, EBSD and TEM characterizations in the present work. The presence of solute in solid solution exhibits a stronger effect on the work hardening of the materials during cryo rolling than the presence of non-coherent and coherent second phase particles. The fine precipitates are sheared and dissolved at a cryorolling strain of 2.3, while the coarse precipitates remain unaffected. The work hardening rate of solutionized material is not saturated even at a cryorolling strain of 2.3, while it is saturated at this strain for the precipitated material. The severe strain induced during plastic deformation of Al 6063 alloy produces ultrafine microstructures with improved strength and hardness. The ageing treatment of the solutionized material after cryorolling at a strain of 2.3 has improved its strength and ductility significantly as compared to precipitated materials due to the precipitation hardening and grain coarsening mechanisms, respectively.
Efficient heat dissipation in lithium-ion battery packs is crucial for safety, necessitating a thorough assessment of thermal performance during the design phase. This study utilizes Newman's Pseudo ...two-dimensional (P2D) model and three-dimensional computational fluid dynamics to depict heat generation and dissipation. The main objectives include evaluating heat dynamics, establishing optimal temperature limits, and assessing State of Charge (SOC) and State of Health (SOH) estimations. The battery pack, configured in 6s2p, features plastic-wrapped cylindrical modules with air-filled domains, connected in parallel pairs with aluminum wires. Active materials comprise positive electrodes like Lithium Cobalt Oxide (LCO), Lithium Nickel Manganese Cobalt Oxide (NMC), Lithium Iron Phosphate (LFP), and Lithium Manganese Oxide (LMO), with graphite as the negative electrode and a separator (Lithium Hexa Fluoro Phosphate). Results indicate that air-cooled NMC electrode chemistry achieves a peak heat dissipation of 102.48W, maintaining an optimal temperature range of 21.3deg C to 32.8deg C. After 1000 cycles, the optimal temperature limit of 32.8deg C with an 80% capacity loss minimizes negative impacts during charge/discharge cycles. SOC and SOH remain at 100% and 80%, utilizing an 8Ah battery with a nominal voltage of 4.2V, and a 3.9-year life expectancy, addressing charge/discharge cycle issues.
In the present investigation, grain refinement mechanism in 6082 Al alloy fabricated by multi-axial forging at liquid nitrogen temperature (MCF) was proposed. The hardness and tensile properties were ...correlated to the microstructural characteristics of the processed alloy. The samples were subjected to open die MCF up to the 2 cycle (true strain = 1.26), 4 cycle (true strain = 2.52), and 6 cycle (true strain = 3.78), respectively. With the increased number of induced forging cycles, strength of the processed samples was significantly increased. The number density of dynamic recrystallized (DRXed) grains has significantly increased as the number of induced MCF cycles increases. The micro-texture analysis suggested the presence of the strong recrystallization (Rotated Cube ({001} )) and strong deformation (Goss ({110} ) & Cu ({112} )) texture components, after inducing the total true strain of 3.78. The supressed and broadened differential scanning calorimetry (DSC) exothermic peaks of β″&β′-phases of the MCF up to 6 cycles have revealed the high dislocation density in the processed samples. The MCF up to 6 cycles, followed by isochronal annealing treatment of Al alloy exhibit the highest strength in all investigated conditions. It was occurred due to the grain boundary strengthening owing to the development of nano-size sub-grains, as well as formation of needle shape β″-phases, which imparted the greater pinning effect during the interaction with the dislocations and grain boundaries.
AlSi10Mg alloy was fabricated by Selective Laser Melting (SLM) using two different atmospheres, argon and nitrogen, both in vertical and horizontal built directions. The influence of work environment ...and anisotropy are studied in this work by keeping all other process parameters including shielding gas pressure constant. The meso-structural features revealed scan tracks and melt pool layers while the microstructural features have showed cellular structure with α-Al matrix and its boundary made up of the eutectic mixture of Al and Si. These cells were approximately of 500 nm size as revealed by TEM analysis. The grain morphology and texture were studied using EBSD analysis. The XRD analysis revealed similarity in the phases formed in samples built under argon and nitrogen environment. Both the horizontal as well as vertical built samples contain elongated grains with 〈100〉 direction oriented along the built direction and 〈100〉 fibre texture in the XY plane. Tensile test results showed the maximum strength of 385 ± 5 MPa was exhibited by vertically built sample under nitrogen environment while the lowest strength of 338 ± 2 MPa was exhibited by horizontally built sample under argon environment. Surface roughness and porosity measured in all the conditions exhibited minor variation in the average surface roughness and porosity area fraction values. Among the samples tested under same built orientation, the variation in strength is approximately 5% higher in nitrogen environment while among the samples tested under same working environment, the variation in strength is approximately 7.5% higher in vertically built samples. This states that the influence of working environment on strength is lesser than that of the built orientation. The materials exhibited brittle failure with inclined fracture profile, fracture morphology with pores, river patterns and inter-cellular fracture plus approximately 4.5% elongation in all the tested samples, implied isotropic elongation behaviour. The samples built under both the work environments exhibited the similarity in defect structure, microstructure and nearly isotropic behaviour in mechanical properties. It inferred that nitrogen could be preferred over argon as shielding gas in SLM for its cost effectiveness.
► Solution treated bulk Al 6063 alloys were subjected to cryorolling and room temperature rolling. ► The effects of rolling temperature and strain on the refinement of alloy are investigated. ► The ...heat treatment conditions are optimized by EBSD, and mechanical testing before rolling. ► The recrystallized grains with the high angle grain boundaries occur at the strain value of 3.8. ► The sub-grains are not recrystallized for the room temperature rolled samples.
The effects of rolling temperature and rolling strain on the microstructural refinement of Al 6063 alloy are investigated in the present work by employing electron back scattered diffraction (EBSD) analysis, transmission electron microscope (TEM) investigations, and X-ray diffraction (XRD) analysis. The solution treated bulk Al 6063 alloy samples are subjected to cryorolling and room temperature rolling to produce sheets with different strain levels such as 0.4, 2.3 and 3.8, respectively. Prior to cryorolling and room temperature rolling, the initial conditions such as solution treatment temperature, and sample immersion duration time, in liquid nitrogen, before cryorolling are optimized by using EBSD analysis, TEM investigations, hardness test, and tensile test. It is observed that the formation of recrystallized ultrafine-grains with the high angle grain boundaries occurs at the strain value of 3.8. However, in case of room temperature rolled samples, the sub-grains are not recrystallized even up to the strain value of 3.8.
A study on the mechanical properties of cryorolled Al–Mg–Si alloy Panigrahi, Sushanta Kumar; Jayaganthan, R.
Materials science & engineering. A, Structural materials : properties, microstructure and processing,
05/2008, Letnik:
480, Številka:
1
Journal Article
Recenzirano
The mechanical properties of a precipitation hardenable Al–Mg–Si alloy subjected to cryorolling and ageing treatments are reported in this present work. The severe strain induced during cryorolling ...of Al–Mg–Si alloys in the solid solutionised state produces ultrafine microstructures with improved mechanical properties such as strength and hardness. The improved strength and hardness of cryorolled alloys are due to the grain size effect and higher dislocation density. The ageing treatment of cryorolled Al–Mg–Si alloys has improved its strength and ductility significantly due to the precipitation hardening and grain coarsening mechanisms, respectively. The reduction in dimple size of cryorolled Al–Mg–Si alloy upon failure confirms the grain refinement and strain hardening mechanism operating in the severely deformed samples.
This study deals with the development of drum brake liner for a multi-utility vehicle possessing a hydraulic brake system by varying 7 weight % of steel fiber and stainless steel fiber each, in ...friction composite formulations. The developed friction composites were tested for physical, chemical, corrosion, mechanical, thermal properties, and tribological characteristics, under near-actual conditions using an inertia dynamometer as per industrial standards. Finite element analysis software (ANSYS) analysis was performed to show the thermal stress distribution of the developed friction composites at the maximum temperature rise due to heat generated during brake stops, and an extensive evaluation method was used to rank the composites. The study concludes that the brake factor of the stainless steel fiber-based friction composite produces stable performance in all conditions with a lower liner temperature rise of 340 °C and lower thermal stress at 4.255294 MPa. However, the steel fiber-based composites produced high performance at the beginning but deteriorated after a certain period due to higher levels of corrosion and a high temperature rise of 361 °C resulting in a negative fade (−0.84%) and more thermal stress (5.619102 MPa). The primary plateau, secondary plateau, back transfer of drum wear debris, and the distribution of constituents on the worn surface of the developed composites in a resin matrix were identified and studied using a scanning electron microscope (SEM) equipped with energy-dispersive spectroscopy.
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