Will powder coating affect the strength of my mtb aluminum frame?

The frame has already gone through heat treatment during the manufacturing process.Will powder coating affect the strength of my mtb aluminum frame?
No. The application of powdercoat will NOT affect the frame strength.





If the frame was built of 7000 series aluminum (usually 7005) it was probably NOT heat treated since this type of alloy has less of a need to be treated.





The problem rears its head when the old paint is removed... if it is sandblasted the frame will become work hardened and worthless.





Make ABSOLUTELY sure that whoever removes the old paint uses a solvent bath (paint remover) or walnut chips to blast off the old finish. If it has been sandblasted you will need to have the frame annealed and retempered before painting... a VERY expensive proposition.Will powder coating affect the strength of my mtb aluminum frame?
no, but it'll be a bit heavier, like 2 or 3 grams, which is like nothing
I personally would not risk it. I've worked with two different powdercoating shops (for coating my own parts), and they refuse to coat any critical aluminum items that have been specifically heat treated, for fear that the temper could be changed in their curing ovens.





Without knowing your alloy, or its temper, there's no specific way to research what 45 minutes of 400 degrees might do to it. At the very least your frame will undergo some serious expansion, and if the stresses were not normalized AFTER welding, that might anger one of the welds if it had any imperfections.





If it was HEAT TREATED, your frame is probably 6061, which is hardened through a complex series of steps that I don't profess to understand, but that are VERY specific. One of those steps ';hardens'; the aluminum, and is often done at temperatures similar to those in a Powdercoating oven. In the Military Handbook for Metallic Materials and Elements for Aerospace Vehicles and Structures, page 3-14, they specify that no heat-treatable alloy should be subjected to temperatures between 212-400 degrees, because it will change the temper in some way.





The only exception they give, is if the initial hardening step was deliberately skipped, because the later exposure to the higher temperatures was planned/known in advance. You run the risk of, at the very least, having your frame be further hardened by the powdercoating, which will make it more brittle, and less ';tough';. Not good for a mountain bike. Since both 6061 and 7005 are heat treatable alloys, I'm sure either one could be affected by time in an oven. In fact, 7005 becomes even ';harder'; than 6061, which could be why it is often left ';as is'; (no heat treatment) when constructing bikes. The last thing a mountain bike frame needs to be, is too ';hard';.





If you're still sold on powder coating, a good idea might be to call the manufacturer of your bike's frame (some of their websites recommend this), and see what they say. Some powder coaters have no clue about metalurgy, so do your OWN research, and don't just accept the ';it will be fine'; answer you might get from them.





If it were my bike, I'd get it painted, and keep the heat away from it.





Good Luck