In the present work, ultrafine grained Al 6082 alloy was produced by cryorolling (CR), room temperature rolling (RTR), CR + annealing (CR + AN) at 200 °C and RTR + annealing (RTN + AN) at 200 °C processes to study the effects of metallurgical factors (ultrafine grain structure, precipitates and secondary phase particles) on its low cycle fatigue behavior. Various characterization techniques such as the transmission electron microscopy, electron back scattered diffraction, scanning electron microscopy and differential scanning calorimetry were used to investigate the low cycle fatigue (LCF) behavior of the 6082 Al alloy. It was observed that the sample produced via CR + AN exhibits the highest LCF life when compared to the other samples investigated. The improvement in the LCF life of the 6082 Al alloy after CR + AN is attributed to the presence of small sized Si-rich precipitates, secondary phase particles, sub grains formation (200–400 nm) and high stored energy (32.16 × 10−4 J/mol). © 2018 Elsevier Ltd

Rengaswamy Jayaganthan

Department of Engineering Design

Aluminum

Differential scanning calorimetry

Electron microscopy

Fatigue of materials

High resolution transmission electron microscopy

Metallurgy

Rolling

Scanning electron microscopy

Transmission electron microscopy

AL-ALLOY

Characterization techniques

Electron back-scattered diffraction

LOW CYCLE FATIGUE BEHAVIOR

LOW CYCLE FATIGUES

STRAIN AMPLITUDE

Ultra fine grain

ULTRAFINE GRAIN STRUCTURES

Aluminum alloys

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IIT Madras

International Journal of Fatigue

In the present work, aluminium alloys were subjected to two different severe plastic deformation (SPD)routes namely, cryorolling (CYR)and constrained groove pressing (CGP), to investigate their effect on microstructure and mechanical properties. Solutionized AA 5083 alloy and AA 6061 alloy sheets were cryorolled to a final thickness of 1 mm with a total logarithmic strain of 1.87. Samples of these alloys with 3 mm thickness were subjected to CGP with an equivalent plastic strain of 1.16. The CGP samples have been subsequently cold rolled (CR)to reduce the thickness to 1 mm (67% reduction). The microstructure of the deformed samples was characterized by electron backscatter diffraction (EBSD)coupled with kernel average misorientation (KAM)and X-ray diffraction (XRD). The techniques were employed to investigate the degree of grain refinement and local misorientation due to deformation. It has been found that the yield strength (YS)of 6061 alloy after CGP + CR is 19% higher than that of CYR sample while, in contrast, the YS of CGP + CR 5083 alloy is 18% less than that of CYR condition. A dislocation density-based model has been used to estimate the sub-structural changes during processing. The theoretical dislocation density estimated using the model agreed well with the experimental values of both the alloys with a difference of about 2.5% in the case of 5083 and 6.5% in the case of 6061. It is inferred from the analysis that the dislocation bow out is the predominant mechanism in both the materials. © 2019

Materials Science and Engineering A

Development of combined groove pressing and rolling to produce ultra-fine grained Al alloys and comparison with cryorolling

The main objective of the present study was to investigate the effect of Mg/Si precipitates on the hot-compression response of Al-Mg-Si alloy and further inspect the influence of compression temperatures and Mg/Si precipitates on microstructural changes. The processing maps were drawn using the dynamic materials model approach. To validate the processing maps, metallurgical factors of different regions of processing map were investigated using differential scanning calorimetry (DSC) and electron back-scattered diffraction. The influence of strain rate on the flow stresses of Al-Mg-Si alloy is not consistent with the traditional results after compression from 100 to 250 °C, due to the strain ageing produced by the Mg/Si precipitates. The DSC study reveals that no Mg/Si precipitate evolved during the compression test after compressing beyond 250 °C. The processing maps (drawn at 0.1 true strain to 0.6 true strain) and metallurgical factors (high-angle grain boundaries or dynamic recrystallized grains) indicated that hot-compression efficiency of Al-Mg-Si alloy is significantly improved after compression beyond 250 °C, because no Mg/Si precipitates evolved. © 2019, ASM International.

Journal of Materials Engineering and Performance

Hot-Compression Response of Solution-Treated Al-Mg-Si Alloy

The influence of cryorolling (CR), room temperature rolling (RTR) and post annealing on precipitation, microstructural evolution (recovery, recrystallisation and grain growth), mechanical and corrosion behavior, was investigated in the present work. The precipitation kinetics and microstructural morphology of CR, RTR, and post annealed samples were investigated by differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and electron back scattered diffraction (EBSD) to elucidate the observed mechanical properties. After annealing at 200 °C, UTS and hardness of CR samples (345 MPa and HV 127) were improved as compared to RTR samples (320 MPa and HV 115). The increase in hardness and UTS of CR samples after annealing at 200 °C was due to precipitation of β″ from Al matrix, which imparted higher Zener drag effect as compared to RTR samples. The improvement in corrosion and pitting potentials was observed for CR samples (−1.321 V and −700 mV) as compared to RTR samples (−1.335 V and −710 mV). In CR samples, heavy dislocation density and dissolution of Mg4Al3Si4-precipitates in the Al matrix have improved corrosion resistance of the alloy through formation of protective passive layer and suppression of galvanic cell, respectively. © 2017 The Nonferrous Metals Society of China

Transactions of Nonferrous Metals Society of China (English Edition)

Effect of deformation temperature on precipitation, microstructural evolution, mechanical and corrosion behavior of 6082 Al alloy

In the present work, the effect of grain boundary misorientation, deformation temperature and AlFeMnSi-phase on fatigue behavior of 6082 Al has been investigated. The 6082 Al alloy has been subjected to cryorolling followed by warm rolling at 100 °C–250 °C. The fatigue test of the processed alloy has been performed at stress ratio (R) of zero with different stress amplitude of 25, 50, 60, 70, 80, 90, and 110 MPa. The deformed alloy and fracture surface was characterized by using XRD, DSC, SEM and EDS to elucidate the role of AlFeMnSi-phase and Mg2Si-precipitates on fatigue life of the alloy. Cryorolling followed by Warm rolling (CR + WR) 6082 Al alloy rolled at 100 °C temperature showed higher dislocation density compared to other processed sample. The small size of AlFeMnSi-phase and Mg2Si-precipitates, high dislocation density and low angle grain boundaries had improved the fatigue life of 6082 Al alloy as observed in the present work. © 2017 Elsevier Inc.

Materials Characterization

Effect of grain boundary misorientaton, deformation temperature and AlFeMnSi-phase on fatigue life of 6082 Al alloy

The mechanical and corrosion behavior of Al alloy 6082-T6 subjected to solution heat treating condition at temperatures varying from 400 to 600 °C and soaking times of 3–24 h have been investigated. Solution heat treating at 550 °C for 24 h led to the dissolution of the Mg2Si and AlSi6Mg3Fe precipitates into the matrix, and the Al12(FeMn)3Si2 phase transformed into Al85(Fe0.28Mn0.72)14Si phase. The solution-treated alloy showed equiaxed grain morphology with an average grain size of 85.7 µm. Increasing the solution heat treating temperature beyond 550 °C caused a reduction in corrosion resistance of the alloy. The pitting potential increased due to the presence of the anodic phase Mg2Si (dissolved at 550 °C) in Al matrix and it decreased with the formation of cathodic phases such as AlSi6Mg3Fe and Al12(FeMn)3Si2 (dissolved at 550 °C/24 h) in the alloy. General corrosion resistance of the alloy increased with decreasing Mg2Si concentration in the Al matrix. The optimum solution heat treating condition of 550 °C for 24 h resulted in an improvement in hardness (63 VHN), ultimate tensile strength (UTS—208 MPa), and pitting potential (−675 mV) and uniform corrosion potential (−1.255 mV) of 6082 Al alloy. © 2015, Springer Science+Business Media New York and ASM International.

Metallography, Microstructure, and Analysis

Effect of Solution Treatment on Mechanical and Corrosion Behaviors of 6082-T6 Al Alloy

In the present work influence of annealing on precipitation phenomena, thermal stability and grain growth kinetics of a bulk ultrafine grained (UFG) Al 2014 alloy has been studied. As-received solution treated Al 2014 alloy is subjected to cryorolling (CR) to develop ultrafine grained microstructure and subsequently, annealing treatment in the range of 323 K (50 °C) to 673 K (400 °C) for the duration of 30 min is done to study its thermal stability. The recrystallization process of the cryorolled Al 2014 alloy starts at 373 K (100 °C) and completes at 523 K (250 °C). The UFG microstructure is retained in the CR Al 2014 alloy up to 623 K (350 °C). The high thermal stability of the UFG grained Al 2014 alloy is due to pinning action of precipitate particles of Cu2Al and AlCuMgSi phases which are within the range of 100 nm and lying along the grain boundaries. The activation energy required for grain growth of the CR Al 2014 alloy is found to be exceptionally high as compared to other processing routes. © 2015 Elsevier B.V. All rights reserved.

Journal of Alloys and Compounds

Precipitation phenomena, thermal stability and grain growth kinetics in an ultra-fine grained Al 2014 alloy after annealing treatment

In the present study, recovery, recrystallisation, grain growth, mechanical, and corrosion resistance of 6082 Al alloy subjected to cryorolling (CR) and annealing (AN) treatment were investigated. CR was performed to produce ultrafine grained structure and subsequently, AN treatment was given to investigate its influence on recovery, recrystallisation, and grain growth. The recovery and recrystallisation occurs between 110 and 250 C and 250-300 C respectively, where as grain growth starts from 300 C due to insoluble dispersions (AlMn &amp; AlMnSi) and Mg2Si precipitates in the alloy as evident from Differential scanning calorimetry (DSC), Electron back scattered diffraction (EBSD), hardness and Transmission electron microscopy (TEM) results. CR 6082 Al alloy has showed increased hardness of 120 VHN and ultimate tensile strength of 353 MPa. Annealing of CR 6082 Al alloy at 150 C exhibited maximum hardness, ultimate tensile strength (UTS) and ductility of 127 VHN, 362.5 MPa, and 11%, respectively. CR of the 6082 Al alloy has produced high density of dislocation and increase in grain boundary area, which enabled the formation of dense oxide film on surface, enhancing its corrosion resistance. CR samples annealed at 350 C shows excellent corrosion resistance as compared to as deformed Al alloy. © 2015 Elsevier B.V. All rights reserved.

Materials Chemistry and Physics

Effect of cryorolling and annealing on recovery, recrystallisation, grain growth and their influence on mechanical and corrosion behaviour of 6082 Al alloy

The influence of metallurgical factors on low cycle fatigue behavior of ultra-fine grained 6082 Al alloy

Journal	Data powered by TypesetInternational Journal of Fatigue
Publisher	Data powered by TypesetElsevier Ltd
ISSN	01421123
Open Access	No