1. Firstly, qualified chemical composition is the important precondition.
Before aluminium extrusion, make sure that aluminium composition indicators meet the requirements of national standard, especially the contents of Si, Mg, which has important influence on its mechanical properties. The main reinforce of aluminium alloy 6061 is Mg2Si, if enough Mg2Si cannot be formed, the subsequent solid solution treatment, quenching and aging are meaningless, it has nothing to do with reinforcement.
2. Strictly control process when extruding aluminum profiles is a key factor to get the results of good mechanical properties.
In the production due to the limitation of the actual conditions, the worker often has the difficult to control the process, and doesn’t realize the importance of technology, the temperature and speed controlled is lax, resulting in the limitation of aluminum products, mechanical performance is unqualified.
If the aluminium bar’s temperature is not high enough, the temperature of alloy’s solution treatment cannot be reached, and the fortifier Mg2Si cannot completely dissolved into the aluminium substrate, thus has not the effect of reinforcement; if the aluminium bar’s temperature is much higher, not only destroy alloy structure, but also come into the problems such as surface finish and avulsion.
If our cooling effect is not good, alloy after solid solution treatment cannot get rapid cooling, the strengthening phase in the dissolved in the aluminum substrate Mg2Si can’t stable retained in the matrix, with the reduction of temperature Mg2Si will be with the loss of the solubility in the matrix, and slowly precipitation, thus there is no guarantee that the mechanical properties after aging. And if solid solution treatment, can make the profile rapidly cooling, they cannot afford time to precipitate reinforce, will be kept in the matrix, which can have strengthening effect after aging. So temperature control is the key process.
And aluminum in the actual production process, we should according to the cross section of aluminum flexible adjustment of the process parameters, such as some of the wall thickness of the thicker aluminum extrusions, should raise the bar in the process of extrusion temperature, extrusion a little slower, increasing cooling rate, etc., which can ensure to obtain the supersaturated solid solution.
3. The correct aluminum aging process is the assurance of good mechanical properties
Aluminum aging’s main purpose is to have the effect of a dispersion strengthening, makes soluble in matrix in the strengthening phase Mg2Si evenly in the process of aging, the dispersion of the distribution to the substrate, which have the effect of a strengthening. In the process of aging, not sure if our temperature, time, cannot achieve the purpose of limitation, so the mechanical properties of affirmation is not assured.