An investigation on the optimum aging condition for HFQ-processed AA6082 aluminium alloy

Liang, Yuan (2017). An investigation on the optimum aging condition for HFQ-processed AA6082 aluminium alloy. University of Birmingham. M.Sc.

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Abstract

The innovative solution heat treatment, forming and in-die quenching (HFQ) processcombines die forming and quenching in one operation to reduce thermal distortion andspring back effects. However, the hardness of aged HFQ processed AA6082components varied with the positions and the peak hardness of the product is lowerthan AA6082 in T6 condition.
In this project, a Gleeble machine was used to simulate HFQ process to producedeformed AA6082 specimens with the strain ranging from 0 to 30%; a wide range ofaging time at 180C was employed to identify the optimal aging time for a given strain;and a series of materials characterisation techniques were used to investigate themechanism involved including XRD, optical microscopy, SEM, EDX, TEM.
The experimental results have demonstrated that the pre-deformation introduced byGleeble tensile testing after solution heat treatment has a significant impact on theresponse of the deformed AA6082 material to subsequent aging at 180C. In general,the optimal aging time corresponding to the peak hardness for HFQ-simulated samplesdecreases with increasing the strain because the plastic deformation induced defects(such as voids and dislocations) accelerate the aging process. The pre-deformationreduced the peak hardness from 120HV0.3 for T6 conditioned AA6082 to about105HV0.3 due to the accelerated transformation of β’’ to β’ in severely deformedareas. The mechanisms involved are discussed based on TEM studies and the optimalaging time at 180C for different strains is identified.

Type of Work:

Thesis (Masters by Research > M.Sc.)

Award Type:

Masters by Research > M.Sc.

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