Impact of the Direct Ageing Procedure on the Age Hardening Response of Al-Mg-Si 6101 Alloy

Al-Mg-Si alloys are used not only as construction material, but also as a material for electrical conductors. For this application, it is crucial for the alloy to achieve a balance between strength and electrical properties. This is achieved in practice by a combination of strain and precipitation hardening. The current paper focuses on a heat treatment procedure in which the EN AW 6101 alloy is cooled by a flowing air stream from the solutionizing temperature down to the artificial ageing temperature. The proposed procedure, unlike the common heat treatment leading to the T6 temper, allowed for the precipitation of the coarser β” phase with the presence of relatively wide precipitate-free zones. The age hardening response was investigated by Brinell hardness measurements, eddy current testing and microstructural observations using transmission electron microscopy (TEM). The applied heat treatment resulted in slightly lower strength (compared to the T6 temper), but improved electrical performance of the alloy.

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The Effect of Elastic Strain and Small Plastic Deformation on Tensile Strength of a Lean Al–Mg–Si Alloy

Metals ◽

10.3390/met9121276 ◽

2019 ◽

Vol 9 (12) ◽

pp. 1276

Author(s):

Eva Anne Mørtsell ◽

Ida Westermann ◽

Calin Daniel Marioara ◽

Ketill Olav Pedersen ◽

Sigmund Jarle Andersen ◽

...

Keyword(s):

Heat Treatment ◽

Plastic Deformation ◽

Elastic Strain ◽

Solution Heat Treatment ◽

Small Deformation ◽

Age Hardening ◽

Strength Increase ◽

Artificial Ageing ◽

Small Plastic ◽

Small Plastic Deformation

Al–Mg–Si alloys are usually formed into their final shape by rolling or extrusion. After extrusion, the aluminium profiles are usually straightened, causing the material to be subjected to a small plastic deformation. This study demonstrates the positive effect on strength that can be obtained from such small deformation levels or from only elastically straining the material. Elastic straining of a lean Al–Mg–Si alloy, when performed immediately after solution heat treatment, enhances the material yield strength after artificial ageing to T6. Transmission electron microscopy shows that this effect can be attributed to a higher number density and finer dispersion of the age-hardening precipitate needles. Furthermore, introducing a small plastic deformation of 1% after solution heat treatment results in a comparable strength increase to elastically straining the material. In this case, however, the strength increase is due to the increased dislocation density, which compensates for a lower density of precipitate needles. Finally, by combining plastic deformation with a succeeding elastic strain, we demonstrate how elastic strain can cause an on-set of dislocation cell formation in this material.

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A Combined TEM and Atom Probe Approach to Analyse the Early Stages of Age Hardening in AA 6016

Materials Science Forum ◽

10.4028/www.scientific.net/msf.877.231 ◽

2016 ◽

Vol 877 ◽

pp. 231-236 ◽

Cited By ~ 2

Author(s):

Olaf Engler ◽

C. Schäfer ◽

Henk Jan Brinkman ◽

Calin D. Marioara ◽

Masaya Kozuka ◽

...

Keyword(s):

Atom Probe ◽

Age Hardening ◽

Artificial Ageing ◽

Phase Decomposition ◽

Number Density ◽

Early Stages ◽

Transmission Electron ◽

Different Types ◽

6Xxx Series ◽

Insight Into

In this study we aim at combining the results from transmission electron microscopy (TEM) and atom probe tomography (APT) to study the early stages of phase decomposition in the age hardening alloy AA 6016. Samples are subjected to different periods of natural ageing or artificial pre-ageing at elevated temperature in order to produce different types of clusters and early stages of precipitation before age hardening commences. APT is utilized to detect clusters and identify their compositions, whereas TEM is applied to analyse and quantify number density and sizes of the particles during artificial ageing at 185°C. It is shown that the two techniques, TEM and APT, are complementary and a combined approach yields more detailed insight into the early stages of phase decomposition in age hardening 6xxx series alloys than possible by the sole use of either technique individually.

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Effect of Pre-Straining and Natural Aging on the Hardening Response during Artificial Aging of EN AW 6082 and Lead Free EN AW 6023 Aluminium Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.952.82 ◽

2019 ◽

Vol 952 ◽

pp. 82-91

Author(s):

Martin Fujda ◽

Miloš Matvija ◽

Peter Horňak

Keyword(s):

Aluminium Alloys ◽

Artificial Aging ◽

Solution Treatment ◽

Natural Aging ◽

Age Hardening ◽

Aging Effects ◽

Β Phase ◽

Transmission Electron ◽

Negative Effect ◽

Microscopy Characterization

In order to study the pre-straining and natural aging effects on the age-hardening response of EN AW 6082 and EN AW 6023 aluminium alloys during artificial aging at 170°C, the pre-straining by 5% was performed immediately after solution treatment of alloys at 550°C and subsequent quenching. The age-hardening response during artificial aging applied after various natural aging time (from 0.1 to 5 000 hours) was investigated using Vickers microhardness measurements and transmission electron microscopy characterization. It was found that pre-straining of quenched alloys state caused a dislocation density increasing in solid solution, which resulted in an immediate microhardness increase of alloys. During the subsequent natural aging of EN AW 6082 alloy, its microhardness increased right after alloy quenching and pre-straining, but only to the values obtained for the unstrained alloy state. On the contrary, the hardness of pre-straining EN AW 6023 alloy that is alloyed by Sn did not increase either after 10 hours of natural aging. This phenomenon is attributed to the effect of Sn on suppression of the strengthening clusters formation. The hardness of alloys increased greatly during artificial aging after pre-straining and natural aging due to accelerating the formation of coherent β″-phase particles. The negative effect of natural aging on the maximum age-hardening response obtained during alloys artificial aging had been observed for most of the pre-strained and naturally aged alloys states, with exception of EN AW 6023 alloy states that were pre-strained and shortly naturally aged (up to 100 hours).

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Microstructure Changes and Improvement in the Mechanical Properties of As-Cast AlSi7MgCu0.5 Alloy Induced by the Heat Treatment and ECAP Technique at Room Temperature

Advances in Materials Science and Engineering ◽

10.1155/2018/5697986 ◽

2018 ◽

Vol 2018 ◽

pp. 1-11 ◽

Cited By ~ 3

Author(s):

Miloš Matvija ◽

Martin Fujda ◽

Ondrej Milkovič ◽

Marek Vojtko ◽

Róbert Kočiško ◽

...

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Room Temperature ◽

Cast Alloy ◽

Artificial Ageing ◽

Angular Pressing ◽

Selected Area Electron Diffraction ◽

Transmission Electron ◽

Alloy State ◽

Eutectic Si

The changes in the microstructure and improvement in the mechanical properties of as-cast AlSi7MgCu0.5 alloy induced by the heat treatment and technique of equal channel angular pressing (ECAP) were investigated. The heat treatment of as-cast alloy performed before the ECAP technique was required to increase the plasticity of the alloy. Therefore, the samples of analysed alloys were solution annealed at optimized temperature of 823 K for 4 hours to dissolve the particles of intermetallicπ(Al8FeMg3Si6) phase and to spheroidize the Si particles. Subsequently, water quenching and artificial ageing at optimized temperature of 573 K for 5 hours was used to obtain an overaged alloy state. The microstructure of alloy was consisted ofα(Al) solid solution, eutectic Si particles, and intermetallicβ(Mg2Si), Q-Al4Mg5Si4Cu,α-Al12(Fe,Mn)3Si, and/orα-Al15(Fe,Mn)3Si2phase particles. The crystal structure of present phases was confirmed by hard X-ray diffraction at Deutsches Elektronen-Synchrotron (DESY) in Hamburg and by the selected area electron diffraction (SAED) performed inside the transmission electron microscope (TEM). The heat-treated alloy was processed by ECAP at room temperature following route A. Repetitive ECAP of alloy homogenized the heterogeneous as-cast microstructure and formed the ultrafine subgrain microstructure with elongated subgrains of 0.2 µm in width and 0.65 µm in length and the high dislocation density. Microstructural changes in alloy induced by both heat treatment and ECAP led to the high strain hardening of the alloy that appeared in an improvement in strength, ductility, and microhardness of alloy in comparison with as-cast alloy state.

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The Ageing Behavior of Titanium Alloy Ti-10V-2Fe-3Al

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.843 ◽

2010 ◽

Vol 654-656 ◽

pp. 843-846 ◽

Cited By ~ 2

Author(s):

Huda Al-Salihi ◽

Colleen J. Bettles ◽

Barry C. Muddle

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Solution Treatment ◽

High Strength ◽

Rapid Quenching ◽

Age Hardening ◽

Slow Cooling ◽

Punch Test ◽

Β Phase ◽

Shear Punch Test

A good combination of high strength and hardenability makes the alloy Ti 10V-2Fe-3Al a prime candidate for applications in the aerospace arena. However, these properties are very dependent on a post-forming heat treatment. The overall objective of this work is to determine the effect of prior deformation on the aging behaviour. In this particular study, the influence of the heat treatment, either solution and/or aging, on the microstructures, and consequently on the mechanical properties, without introduced strain is reported. Various solution heat treatments have been conducted, either in the β phase or in the (α+β) phase field, followed by rapid quenching or slow cooling, and aging treatments at different temperatures (250, 350, 400, 500C°) above and below the ω-transus temperature. Vickers hardness indentations were used to follow the precipitation hardening behaviour, and mechanical properties were determined using a shear punch test. The aging response is dependent not only on the presence of the athermal ω phase but also on the proximity of the aging temperature to the ω-transus. Most treatments showed an unusual initial softening behaviour prior to age hardening, however this appears to be related again to the composition and fraction of the β phase retained after solution treatment.

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Investigation of the Properties of Heat Treated Rolled Aluminum Zinc Alloy (7072-T6)

Wasit Journal of Engineering Sciences ◽

10.31185/ejuow.vol1.iss2.15 ◽

2013 ◽

Vol 1 (2) ◽

pp. 79-91

Author(s):

Kamal Abdulkareem Mohammed

Keyword(s):

Heat Treatment ◽

Mechanical Tests ◽

Phase Region ◽

Zinc Alloy ◽

Artificial Ageing ◽

Zinc Alloys ◽

Β Phase ◽

Alloy Type ◽

Structural Applications ◽

Rolled Aluminum

The effects of heat treatment on the properties of rolled aluminum zinc alloy type 7072-T6 are study in this work. Representative samples of aluminum zinc alloys were subjected to heat treatment processes which are; Solution heat treatment follow by Artificial Ageing in the different order. The aluminum zinc alloys were heated to the initial temperature of 600 ºC and water quenched. The quenched aluminum zinc alloys were subjected to(lamellae formation) by reheating it to the dual-phase region at a temperature of 150ºC and then rapidly quenched in water. The (lamellae formation) samples was take an Artificial Ageing at 400 ºC to provide an alloy containing strong, tough and lath α –β phase in a soft and ductile α - matrix. Mechanical tests were carried out on the samples and the results shows that the aluminum zinc alloys developed has excellent combination of tensile strength, hardness and impact strength which is very good for structural applications.

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HRTEM Observation of the Age Hardening Precipitates in Mg-Gd-Sc Alloys, with Different Gd Concentrations

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.409.335 ◽

2011 ◽

Vol 409 ◽

pp. 335-338

Author(s):

Takafumi Fujii ◽

Kenji Matsuda ◽

Tokimasa Kawabata ◽

Susumu Ikeno

Keyword(s):

Electron Microscope ◽

High Resolution ◽

Transmission Electron Microscope ◽

Age Hardening ◽

Number Density ◽

Maximum Hardness ◽

Β Phase ◽

Transmission Electron ◽

Hrtem Observation

High resolution transmission electron microscope (HRTEM) observations were performed to investigate the age hardening precipitates in Mg-Gd-Sc alloys. The maximum hardness of these alloys increased with Gd content. The precipitates with the features of β” phase and β’ phase in Mg-Gd alloy were observed in Mg-15Gd-6.4Sc and Mg-10Gd-6.4Sc alloys. Maximum hardness and number density of precipitate in Mg-15Gd-6.4Sc alloy were higher than that in Mg-10Gd-6.4Sc alloy, and the finer precipitates with higher number of density were contributed to the maximum hardness in Mg-Gd-Sc alloys.

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Enhancing the High-Temperature Strength of a Co-Base Superalloy by Optimizing the γ/γ′ Microstructure

Metals ◽

10.3390/met10030321 ◽

2020 ◽

Vol 10 (3) ◽

pp. 321

Author(s):

D. Hausmann ◽

C. Solís ◽

L.P. Freund ◽

N. Volz ◽

A. Heinemann ◽

...

Keyword(s):

Heat Treatment ◽

High Temperature ◽

Volume Fraction ◽

Heat Treatments ◽

Age Hardening ◽

Precipitate Size ◽

High Temperature Strength ◽

Compression Tests ◽

Transmission Electron

Compositionally complex polycrystalline γ/γ′ CoNi-base superalloys, such as CoWAlloy2 (Co41-Ni32-Cr12-Al9-W5-Ti0.3-Ta0.2-Si0.4-Hf0.1-C-B-Zr) are interesting candidates for new high-temperature materials. To maximize their high-temperature strength, the γ/γ′ microstructure has to be optimized by adjusting the multi-step heat treatments. Various microstructures after different heat treatments were analyzed by scanning and transmission electron microscopy and especially in-situ small-angle neutron scattering during heat treatment experiments. The corresponding mechanical properties were determined by compression tests and hardness measurements. From this, an optimum γ′ precipitate size was determined that is adjusted mainly in the first precipitation heat treatment step. This is discussed on the basis of the theory of shearing of γ′ precipitates by weak and strong pair-couplings of dislocations. A second age hardening step leads to a further increase in the γ′ volume fraction above 70% and the formation of tertiary γ′ precipitates in the γ channels, resulting in an increased hardness and yield strength. A comparison between two different three-step heat treatments revealed an increase in strength of 75 MPa for the optimized heat treatment.

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Interaction between Cu and Sn in the Early Stages of Ageing of Al-1.7at.%Cu-0.01at.%Sn

Materials Science Forum ◽

10.4028/www.scientific.net/msf.519-521.495 ◽

2006 ◽

Vol 519-521 ◽

pp. 495-500 ◽

Cited By ~ 7

Author(s):

Laure Bourgeois ◽

Timothy Wong ◽

X.Y. Xiong ◽

Jian Feng Nie ◽

Barry C. Muddle

Keyword(s):

Three Dimensional ◽

Atom Probe ◽

Age Hardening ◽

Peak Hardness ◽

Artificial Ageing ◽

Natural Ageing ◽

Number Density ◽

Transmission Electron ◽

Hardening Treatment ◽

Significant Acceleration

The interaction between vacancies and Sn and Cu solute atoms in an Al-1.7at.%Cu- 0.01at.%Sn alloy was investigated by exploring the effect of incorporating natural ageing into conventional age hardening treatment. It was found that provided the artificial ageing temperature does not exceed a critical value between 160°C and 200°C, a narrow window of natural ageing (3-100 h) will result in a significant acceleration of the age hardening response and no decrease in peak hardness. Transmission electron microscopy showed that this effect reflects a large and rapid increase in number density of Cu GP(I) zones, and, to a lesser extent, of θ". The distribution and number density of θ' are essentially unaffected. Three-dimensional atom probe provided strong evidence that refinement of GP(I) zone distribution is not due to clustering of Cu atoms onto pre-existing Sn clusters. Instead it appears to be caused by a subtle interaction between vacancies, Sn and Cu atoms.

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Effect of T6 Heat Treatment on the Microstructure and Hardness of Secondary AlSi9Cu3(Fe) Alloys Produced by Semi-Solid SEED Process

Metals ◽

10.3390/met8100750 ◽

2018 ◽

Vol 8 (10) ◽

pp. 750 ◽

Cited By ~ 7

Author(s):

Alberto Fabrizi ◽

Stefano Capuzzi ◽

Alessandro De Mori ◽

Giulio Timelli

Keyword(s):

Heat Treatment ◽

Heat Treatments ◽

Solution Temperature ◽

Artificial Ageing ◽

Solid Alloy ◽

T6 Heat Treatment ◽

Transmission Electron ◽

Eutectic Si ◽

Peak Aged ◽

Semi Solid

The effect of the T6 heat treatment on the microstructure and hardness of a secondary semi-solid AlSi9Cu3(Fe) alloy have been investigated by using optical, scanning and transmission electron microscopy and hardness testing. The semi-solid alloy was produced using the swirled enthalpy equilibration device (SEED). The solution heat treatments were performed at 450, 470 and 490 °C for 1 to 6 h followed by water quenching and artificial ageing at 160, 180 and 220 °C for holding times ranging from 1 to 30 h. The microstructural investigations have revealed the spheroidization of the eutectic Si and the dissolution of the majority of Cu-rich compounds after all the solution heat treatments; moreover, the greater the solution temperature and time, the higher the hardness of the alloy. Unacceptable surface blistering has been observed for severe solution condition, 490 °C for 3 and 6 h. The artificial ageing at 160 °C for 24 h has led to the highest alloy strengthening thanks to the precipitation of β” and Q’ (or L) phases within the α-Al matrix. The hardening peaks at higher temperatures have been early achieved due to faster hardening kinetic; however, the lower number density of β” and Q’ (or L) phases and the presence of coarser θ’ precipitates result in a reduction of hardness values for peak aged condition at 180 and 220 °C, respectively.

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