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

Abstract

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.

Dissolution and Precipitation Behavior for Hot Forming of 7021 and 7075 Aluminum Alloys

“…Considering the findings of Ref. [22], the solution treatment parameters chosen in this work for EN AW-7021 and 7075, respectively, seem to result in a complete dissolution of the major alloying elements, because a certain undercooling precedes quench induced precipitation in both cases (see Figures 4A and 5A). This hints on the adequacy of the parameters chosen for the solution treatments.…”

“…At the longest investigated natural aging duration of 63 d (1512 h) the resultant hardness from cooling with 300 K/s is slightly higher than after cooling with 100 K/s. A recent work on the influence of the solution treatment on quench induced precipitation in AlMgSi alloys points out the importance of appropriate solution annealing parameters [22]. Considering the findings of Ref.…”

“…cooling with 100 K/s. A recent work on the influence of the solution treatment on quench induced precipitation in AlMgSi alloys points out the importance of appropriate solution annealing parameters [22]. Considering the findings of Ref.…”

In-situ analysis of continuous cooling precipitation in Al alloys by wide-angle X-ray scattering

“…This phenomenon is typically called 'quench-sensitivity' [2][3][4][5][6]. The quench-sensitivity of precipitation hardening aluminium wrought alloys has been intensively studied by differential scanning calorimetry (DSC) in the last decade [7][8][9][10][11][12]. DSC is a powerful in situ method that is capable of detecting cooling precipitation kinetics over a very wide range of cooling rates and allows evaluating the overall precipitation enthalpies [13].…”

“…The maximum strength after ageing can typically be achieved when quench induced precipitation is completely suppressed. The kinetic evolution of quench induced precipitation is described in continuous cooling precipitation (CCP) diagrams, which have been investigated in the authors' previous works for EN AW-7150 [8,9] and EN AW-6082 [10,11]. To obtain such CCP diagrams the kinetic analysis from DSC needs to be complemented by sophisticated microstructural analysis.…”