scholarly journals Comparison of long-term natural aging to artificial aging in Duralumin

2020 ◽  
Vol 326 ◽  
pp. 04007
Author(s):  
Magali Brunet ◽  
Benoit Malard ◽  
Nicolas Ratel-Ramond ◽  
Christophe Deshayes ◽  
Bénédicte Warot-Fonrose ◽  
...  
Keyword(s):  
Aluminium Alloys ◽  
Artificial Aging ◽  
Solution Treatment ◽  
Natural Aging ◽  
Tensile Tests ◽  
Aged Alloy ◽  
Early Failure ◽  
Long Time ◽  
Aging Conditions

The understanding of long-term aging of aeronautical materials, in particular aluminium alloys used in the fuselage and structure of aircraft is of extreme importance for airline fleets. In this work, a plate from an old aircraft (Breguet) was retrieved and studied in terms of microstructure and mechanical properties. A comparison was made between this naturally-aged alloy and a modern alloy on which different artificial aging conditions were applied. The old alloy exhibits a precipitation of θ-Al2Cu at grain boundaries and of Ω-Al2Cu on dispersoids. This non-expected nanostructure for an alloy in T4 state was attributed to the heat that the plate experienced during the aircraft cycles. However, it is shown that this aging is reversible (after a solution treatment). Moreover, the very long time of outdoors exposure seems to have caused intergranular corrosion causing the early failure during tensile tests on some of the specimens. The artificial aging (low temperature, 100°C for up to 10,000h) applied on the modern 2017A alloy did not allow to reproduce the nanostructure of the old plate, meaning that isothermal conditions for artificial aging might not be appropriate in this case.

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

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).

scholarly journals Effect of Cold Rolling on Cluster(1) Dissolvability during Artificial Aging and Formability during Natural Aging in Al-0.6Mg-1.0Si-0.5Cu Alloy

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 92
Author(s):  
Naoto Kirekawa ◽  
Kaisei Saito ◽  
Minho O ◽  
Equo Kobayashi
Keyword(s):  
Cold Rolling ◽  
Artificial Aging ◽  
Cluster Formation ◽  
Solution Treatment ◽  
Natural Aging ◽  
Tensile Tests ◽  
Scanning Calorimetry ◽  
Hardness Tests ◽  
Negative Effect ◽  
Cold Rolled

Natural aging after solution treatment has a negative effect on the precipitation strengthening of Al–Mg–Si alloys since Cluster(1) formed at a room temperature cannot be dissolved or transformed into precipitates during artificial aging at 170 °C. In this study, cold rolling is focused on as an alternative solution to pre-aging, which is a conventional method to prevent Cluster(1) formation. It is known that excess vacancies are necessary for cluster formation. Cold rolling suppresses cluster formation because excess vacancies disappear at dislocations introduced by cold rolling. In addition, it is expected that cold rolling accelerates the precipitation behavior because the diffusion of solute atoms is promoted by introduced lattice defects. The transition of Cluster(1) was evaluated by Micro Vickers hardness tests, tensile tests, electrical conductivity measurements and differential scanning calorimetry analyses. Results showed the negative effect of natural aging was almost suppressed in 10% cold-rolled samples and completely suppressed in 30% cold-rolled samples since Cluster(1) dissolved during artificial aging at 170 °C due to lowering of the temperature of Cluster(1) dissolution by cold rolling. It was found that the precipitation in cold-rolled samples was accelerated since the hardness peak of 10% cold-rolled samples appeared earlier than T6 and pre-aged samples.

Research on Characteristics of Heat Treatment of Squeeze Cast Al-Cu-Mg Alloy

2013 ◽  
Vol 749 ◽  
pp. 54-60
Author(s):  
Yao Qiang Gan ◽  
Lei Lu ◽  
Da Tong Zhang ◽  
Wei Wen Zhang ◽  
Yuan Yuan Li
Keyword(s):  
Heat Treatment ◽  
Tensile Strength ◽  
Solution Heat Treatment ◽  
Artificial Aging ◽  
Squeeze Casting ◽  
Natural Aging ◽  
Mg Alloy ◽  
Solute Diffusion ◽  
Aged Alloy ◽  
Casting Alloy

A high strength Al-Cu-Mg alloy was prepared by squeeze casting. The effects of squeeze casting and heat treatment on the microstructures and mechanical properties of the alloy were studied. It was found that squeeze casting refined the microstructure and reduced the micro-segregation markedly, and also accelerated the diffusion process of solute atoms during solution heat treatment. Tensile strength and elongation of squeeze casting alloy were much higher than those of gravity casting alloy under both the as-cast and heat-treated conditions. In addition, the Al-Cu-Mg alloy prepared by squeeze casting showed good natural aging response, and the naturally-aged alloy possessed a slightly lower tensile strength but better elongation compared to full artificial aging. After solution heat treatment at 495 for 9h and further natural aging for 48h or artificial aging at 190 for 6h, the tensile strength of squeeze casting alloy reached to 472MPa and 475MPa, respectively, and the elongation was 18.9% and 12.7% accordingly. Based on the experimental results, the mechanism of microstructural evolution of squeeze casting Al-Cu-Mg alloy during heat treatment was discussed, and the effect of squeeze casting on the kinetics of solute diffusion and aging precipitation was studied.

Studying the Effect of Precipitation Hardening on 6061 Aluminum Alloy Weldments

2016 ◽  
Vol 1133 ◽  
pp. 300-304
Author(s):  
Tahir Ahmad ◽  
Muhammad Kamran ◽  
Muhammad Faizan ◽  
Rafiq Ahmad ◽  
Bamban Ariwahjoedi ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Aluminium Alloys ◽  
Artificial Aging ◽  
Precipitation Hardening ◽  
Solution Treatment ◽  
Maximum Hardness ◽  
6061 Aluminum Alloy ◽  
Specific Strength ◽  
High Specific Strength ◽  
Aging Precipitation

The high specific strength, ease of working, good weldability and the ability to be precipitation strengthening have increased the demand of aluminium alloys in aerospace and automobile industries. In this research the effect of artificial aging/precipitation hardening on mechanical properties and microstructures of 6061 aluminum alloy weldments produced using gas tungsten welding (TIG) was studied. The artificial aging of welded alloy was carried out at temperatures varying from 150°C to 170°C for different period of time. The Vickers hardness and tensile test were carried out to evaluate the response of material to heat treatment. The experimental work showed that the maximum hardness and tensile strength of 6061 aluminum welded samples was achieved when aged at 170°C (after solution treatment) for 2 and 10 hours. Scanning electron microstructure analysis revealed that after solution treatment, when the samples were aged at 150-170°C, the Mg2Si precipitates present in the grains grows in size and develop stress in the grain and resulted increment in hardness.

scholarly journals Peening Natural Aging of Aluminum Alloy by Ultra-High-Temperature and High-Pressure Cavitation

2021 ◽  
Vol 11 (7) ◽  
pp. 2894
Author(s):  
Toshihiko Yoshimura ◽  
Masayoshi Iwamoto ◽  
Takayuki Ogi ◽  
Fumihiro Kato ◽  
Masataka Ijiri ◽  
...  
Keyword(s):  
Residual Stress ◽  
High Pressure ◽  
Aluminum Alloy ◽  
High Temperature ◽  
Compressive Residual Stress ◽  
Artificial Aging ◽  
Solution Treatment ◽  
Natural Aging ◽  
Aging Treatment ◽  
Ultra High Temperature

The peening solution treatment was performed on AC4CH aluminum alloy by ultra-high-temperature and high-pressure cavitation (UTPC) processing, and the peening natural aging was examined. Furthermore, peening artificial aging treatment by low-temperature and low-pressure cavitation (LTPC) was performed, and the time course of peening natural aging and peening artificial aging were compared and investigated. It was found that when the AC4CH alloy is processed for an appropriate time by UTPC processing, compressive residual stress is applied and natural aging occurs. In addition, the UTPC processing conditions for peening natural aging treatment with high compressive residual stress and surface hardness were clarified. After peening artificial aging by LTPC processing, the compressive residual stress decreases slightly over time, but the compression residual stress becomes constant by peening natural aging through UTPC treatment. In contrast, it was found that neither natural nor artificial peening natural aging occurs after processing for a short time.

Effects of Long-Term Service on The Aging Behavior of A Water-Quenched U6Nb Alloy

2006 ◽  
Vol 986 ◽  
Author(s):  
Jikou Zhou ◽  
Luke L. Hsiung
Keyword(s):  
Natural Aging ◽  
Antiphase Domain ◽  
Aged Alloy ◽  
Aging Behavior ◽  
Ambient Temperatures ◽  
Transmission Electron ◽  
Domain Boundaries ◽  
Nucleation And Growth Mechanism ◽  
Peak Value

AbstractMicrohardness testing and transmission electron microscopy are used to study the effects of long-term service on the aging behavior of a water-quenched U-6wt.% Nb alloy when subjected to isothermal aging at 200°XC. The original α''c phase in the WQ-U6Nb alloy is found to become partially ordered over 18 years of aging at ambient temperatures, i.e., natural aging, forming a microstructure that is featured by antiphase domain boundaries (APBs). When subsequently aged at 200 °C, an ordered phase U3Nb is precipitated through a nucleation-and-growth mechanism, suppressing spinodal decomposition that occurs when the water-quenched alloy is artificially aged at the same temperature. The different phase transformation paths lead to different microhardness changes during artificial aging: the naturally aged alloy is more slowly hardened, but to a greater microhardness peak value.

scholarly journals Microstructure development during thermomechanical treatment of Al-Mg-Si alloy

2002 ◽  
Vol 38 (3-4) ◽  
pp. 153-162 ◽  
Author(s):  
Z. Martinova ◽  
G. Zlateva
Keyword(s):  
Electrical Conductivity ◽  
Thermomechanical Treatment ◽  
Artificial Aging ◽  
Cold Deformation ◽  
Natural Aging ◽  
Tensile Tests ◽  
Prolonged Storage ◽  
Recovery Processes ◽  
Transmission Electron ◽  
Lower Aging Temperature

The effect of natural aging and 95% cold deformation on the microstructure evolution and aging characteristics in commercial Al - 1 mass % Mg2Si alloy subjected to thermomechanical treatment (TMT) was examined. Transmission electron microscopy observations, tensile tests and electrical conductivity measurements were carried out in order to correlate microstructural features to properties on each TMT step. It was established that pre-aging at room temperature affected the morphology of dislocation structure induced by next cold deformation. The observed transition from cellular to homogenous dislocation distribution was explained by the different stability of zones produced by pre-aging of different duration. Natural aging suppressed recovery processes during post-deformation artificial aging, especially after prolonged storage after quenching and at lower aging temperature. It influenced the morphology of precipitates produced by post deformation artificial aging also. The overall effect of TMT involving prior-deformation natural aging in the scheme, on hardness, tensile properties and electrical conductivity is discussed based on experimental microstruture observations.

Effects of Manganese Addition on Tensile Strength of AA6063 Alloy for Marine Application

2012 ◽  
Vol 59 (2) ◽  
Author(s):  
Herman Pratikno ◽  
Mariyam Jameelah Ghazali ◽  
A. R. Daud
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Solution Treatment ◽  
Natural Aging ◽  
Tensile Tests ◽  
Marine Application ◽  
Mn Content ◽  
Cylindrical Steel ◽  
Materials Used ◽  
Aa6063 Alloy

AA6063 alloy is a common materials used in boat and ship construction due to its lightweight and good strength. However, its strength is lower than steel's strength. For that reason, an improvement in strength is needed. In this work, an attempt has been made to improve the tensile strength of AA6063 alloy by adding manganese (Mn) element. From 0.5 to 2.5 wt.% of Mn was added to AA6063 alloy and melted together before being cast into a cylindrical steel mould. The alloy was solutionised at 535oC for 6 hours and followed by water-quenching. The alloy was then artificially aged at 200oC for 5 hours and followed by natural aging for 14 days. Tensile tests were carried out according to ASTM E8M-03 procedures. The combination of artificial and natural aging has increased the ultimate tensile strength of all AA6063 alloys (with and without Mn). The ultimate tensile strength of the alloys increased with the increase of Mn content. An addition of 2.5 wt% Mn has increased the ultimate tensile strength of AA6063 alloy to 189.55 MPa after solution treatment and artificial aging followed by 14 days natural aging compared to as-cast AA6063 alloy which has the ultimate tensile strength of 61.33 MPa.

Behaviour of Artificial Aging in 6066 Alloy Using Microhardness and Nuclear Techniques

2010 ◽  
Vol 305-306 ◽  
pp. 15-22
Author(s):  
Emad A. Badawi ◽  
M.A. Abdel-Rahman ◽  
Alaa El-Deen A. El-Nahhas ◽  
M. Abdel-Rahman
Keyword(s):  
Heat Treatment ◽  
Vickers Hardness ◽  
Artificial Aging ◽  
Solution Treatment ◽  
Natural Aging ◽  
Careful Consideration ◽  
Age Hardening ◽  
Solution Temperature ◽  
Precipitate Size ◽  
Precipitation Heat

Many Aluminum-based alloys are strengthened by using a heat-treatment process known as age-hardening. The aim of this work was to produce a high-strength 6xxx-series Aluminum alloy by adjusting the processing conditions, namely solutionizing and artificial aging. It consists of heating the alloy to a temperature at which the soluble constituents will form an homogeneous mass via solid diffusion, holding the mass at that temperature until diffusion takes place, then quenching the alloy rapidly to retain the homogeneous condition. In the quenched condition, heat-treated alloys are supersaturated solid solutions that are comparatively soft and workable, and unstable, depending upon the composition. After solution treatment and quenching, hardening is achieved either at room temperature (natural aging) or via a precipitation heat treatment at a suitable temperature (artificial aging). Precipitation heat treatments are generally low-temperature, long-term processes. Temperatures range from 115 to 190C; times vary from 5 to 48 h. The choice of time-temperature cycles for precipitation heat treatment should receive careful consideration. The objective is to select the cycle that produces an optimum precipitate size and distribution pattern. The mechanical characterization of heat-treatable 6xxx (Al-Mg-Si-Cu based) 6066 wrought aluminum alloys was studied. Their effects were investigated in terms of microstructure using positron annihilation lifetime techniques and monitoring the mechanical properties by mean of Vickers hardness measurements. The hardness is the resistance of a material to plastic deformation, and gives it the ability to resist deformation when a load is applied. The greater the hardness of the material, the greater resistance it has to deformation. The Vickers hardness of 6066 alloy has its maximum value (98) when aged for (10) hours at (175C) after quenching at 530C; so this temperature is the solution temperature of this alloy .The hardness conformed to reference values.

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