The effects of quench rate and pre-deformation on precipitation hardening in Al–Mg–Si alloys with different Cu amounts

Saito, Takeshi; Marioara, Calin Daniel; Røyset, Jostein; Marthinsen, Knut; Holmestad, Randi

doi:10.1016/j.msea.2014.04.094

Cited by 34 publications

(19 citation statements)

References 41 publications

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“…Two different solution-annealing soaking durations of 1 and 20 min were also examined. Since the slower CALVET-type DSC required at least 5 min to achieve thermal equilibration [13], a soaking duration of 1 min is only investigated in the faster DSCs (0.3-5 K/s). Therefore, a systematic investigation of the quench sensitivity or quench-induced precipitation behavior after different solution-annealing conditions was conducted, and the DSC experiments were performed with three significant parameters varied, as follows: Figure 3 highlights one parameter set of the cooling experiments, plotted according to the 540, 550, and 560 • C solution-annealing temperatures.…”

Section: Continuous Heating Of the T651 Initial Conditionmentioning

confidence: 99%

Influence of Solution-Annealing Parameters on the Continuous Cooling Precipitation of Aluminum Alloy 6082

Fröck

Milkereit

Wiechmann

et al. 2018

Metals

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Abstract:We use a systematic approach to investigate the influence of the specific solution condition on quench-induced precipitation of coarse secondary phase particles during subsequent cooling for a wide range of cooling rates. Commercially produced plate material of aluminum alloy EN AW-6082 was investigated and the applied solution treatment conditions were chosen based on heating differential scanning calorimetry experiments of the initial T651 condition. The kinetics of the quench-induced precipitation were investigated by in situ cooling differential scanning calorimetry for a wide range of cooling rates. The nature of those quench-induced precipitates was analyzed by electron microscopy. The experimental data was evaluated with respect to the detrimental effect of incomplete dissolution on the age-hardening potential. We show that if the chosen solution temperature and soaking duration are too low or short, the solution treatment results in an incomplete dissolution of secondary phase particles. This involves precipitation during subsequent cooling to start concurrently with the onset of cooling, which increases the quench sensitivity. However, if the solution conditions allow the formation of a complete solid solution, precipitation will start after a certain degree of undercooling, thus keeping the upper critical cooling rate at the usual alloy-specific level.

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Section: Continuous Heating Of the T651 Initial Conditionmentioning

confidence: 99%

Influence of Solution-Annealing Parameters on the Continuous Cooling Precipitation of Aluminum Alloy 6082

Fröck

Milkereit

Wiechmann

et al. 2018

Metals

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show abstract

“…This is a very complex process, and everything that occurs after extrusion or after the SHT influences the numbers, size distribution and types of metastable precipitates. [5][6][7][8][9] Therefore, parameters such as cooling rate from extrusion or SHT, room temperature (RT) storage time and pre-deformation before AA, as well as AA temperature and time are crucial for the material properties. To be able to optimize properties and design new alloys, the processes happening at the micro-and nanoscale must be studied and understood.…”

Section: Al-mg-si(-cu) (6xxx) Alloys Are Widely Used Inmentioning

confidence: 99%

The Correlation Between Intergranular Corrosion Resistance and Copper Content in the Precipitate Microstructure in an AA6005A Alloy

Marioara

Lervik

Grønvold

et al. 2018

Metall Mater Trans A

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A positive correlation is observed between the amount of Cu incorporated in hardening precipitates and intergranular corrosion resistance in an artificially aged Cu-containing 6005A alloy. Three mechanisms have been identified to increase Cu absorption in hardening precipitates: by increasing aging temperature, by pre-deformation, and by slow cooling from solution heat treatment. These findings demonstrate the possibility for development of new processing routes to produce Cu-containing Al-Mg-Si alloys with improved corrosion resistance.

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“…This work focuses on the influence of low amounts of Cu (0.01 at.%/0.03 wt.%) because of a reported considerable effect on precipitation when present in higher concentrations ( 0.4 wt.%) [23,[27][28][29]. Previous studies evaluating the effect of low Cu additions looked at lean extruded alloys ( 0.1 wt.%) [26,30,31]. High-resolution transmission electron microscopy (TEM) studies found that 0.1 wt.% Cu had limited effect on the Al-Mg-Si system precipitation, merely affecting the precipitation kinetics and number densities.…”

Section: Introductionmentioning

confidence: 99%

The evolution of precipitate crystal structures in an Al-Mg-Si(-Cu) alloy studied by a combined HAADF-STEM and SPED approach

Sunde

Marioara

Holmestad

2018

Materials Characterization

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This work presents a detailed investigation into the effect of a low Cu addition (0.01 at.%) on precipitation in an Al-0.80Mg-0.85Si alloy during ageing. The precipitate crystal structures were assessed by scanning transmission electron microscopy combined with a novel scanning precession electron diffraction approach, which includes machine learning. The combination of techniques enabled evaluation of the atomic arrangement within individual precipitates, as well as an improved estimate of precipitate phase fractions at each ageing condition, through analysis of a statistically significant number of precipitates. Based on the obtained results, the total amount of solute atoms locked inside precipitates could be approximated. It was shown that even with a Cu content close to impurity levels, the Al-Mg-Si system precipitation was significantly affected with overageing. The principal change was due to a gradually increasing phase fraction of the Cu-containing Q -phase, which eventually was seen to dominate the precipitate structures. The structural overtake could be explained based on a continuous formation of the thermally stable Q -phase, with Cu atomic columns incorporating less Cu than what could potentially be accommodated.

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The effects of quench rate and pre-deformation on precipitation hardening in Al–Mg–Si alloys with different Cu amounts

Cited by 34 publications

References 41 publications

Influence of Solution-Annealing Parameters on the Continuous Cooling Precipitation of Aluminum Alloy 6082

Influence of Solution-Annealing Parameters on the Continuous Cooling Precipitation of Aluminum Alloy 6082

The Correlation Between Intergranular Corrosion Resistance and Copper Content in the Precipitate Microstructure in an AA6005A Alloy

The evolution of precipitate crystal structures in an Al-Mg-Si(-Cu) alloy studied by a combined HAADF-STEM and SPED approach

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