THE EFFECT OF NATURAL AGING TIME ON THE MICROSTRUCTURE

SUMMARY

In the study of the effect of natural aging time on the microstructure and mechanical properties of AA6061 aluminium alloy, the following conclusions were made:

1.         AA6061 aluminium alloy can be strengthened through a process of solution heat treatment and room temperature natural aging for 24 hours.
2.         Continued natural aging after 24 hours can significantly decrease the strength and hardness of the material due to the coalescence of the precipitates into larger particles with bigger grain size by a process known as overaging.
3.         Artificially aging the sample immediately after solution heat treatment at 180^oc for 3 hours gave the best mechanical properties as postulated by Ibunemisam (2019).
4.         A decrease in the mechanical properties during subsequent artificial aging after natural aging has been executed is due to the limited number of GP zones required for the nucleation of β” precipitates which finally nucleates the Mg₂Si needed for strengthening to occur.