Powdercoating 6061-T6 3

[rataz]

G'Day,
Got a question I'm hoping people on here might be able to help me with. We have some 6061-T6 parts that we are looking at getting powdercoated. However I have had some people say that this should be avoided as the temperature at which powdercoating is done (180C) cause a change in the crystal structure of the alloy. This makes the alloy brittle and it is weaker. Can anyone here confirm that at 180C the alloy will change crystal structure? And if so, what temperature would the alloy have to be kept below so that the crystal structure does not change?

Thanks in Advance

Rataz

 

[TVP]

The -T6 from 6061-T6 indicates the heat treatment of this alloy. It is first solution treated by heating to ~ 530 C, then quenched into water, followed by heating for a long time (usually ~ 18 hours) at ~ 160 C. This last portion is called artificial aging or precipitation heat treatment. If you heat the alloy above this temperature during powder coat curing, the precipitates that formed previously begin to overage, reducing strength. The alloy does not become brittle (more prone to brittle fracture), as it actually will have increased elongation before fracture in the overaged condition. It just loses strength, both yield and tensile.