heat treat or not

admin

I'm going to be welding 6061 alum. tubing 1"x1/8" to alum. cast thats about the same thickness in the joining area. Do i need to have these weldments heat treated ?The work is going to be performed on a motocross frame, cutting out the original engine cradles ( no heat) and installing new cradles with new engine mounts that are close to the same thickness as the other parts.
Reply:I would contact the manufacturer of the motorcycle frame and ask their advice.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:Hello mxdogger, the short answer is that the finished frame should be heat-treated if you wish for it to have the strength that it had when it was originally fabricated. The original frame was likely welded, straightened, and then heat-treated as a unit. Welding on heat-treated aluminum(6061T-6 is a heat-treated grade also) and not re-treating it after welding will result in a considerable loss of strength, approx. 1/4 to 1/3 of it's overall strength. I am assuming that you are probably doing a re-power on a particular bike, so in this case if you really want to cover all the bases this will require a complete strip-down and after you have done the necessary welding and changes you will need to find a facility that has the proper equipment and know-how to correctly heat-treat it. There are likely others who can give you a much more technically correct explanation of this, however I believe you get the idea. Safety is always a concern when you are modifying any piece of equipment so you will have to use your best judgement to determine if the modifications that you are doing to the bike might compromise it's safety. Many things can be modified and welded where the service conditions won't exceed the loss in strength, others will definitely compromise integrity and put you at risk. Just a bit for you to consider. Best regards, Allanaevald
Reply:thanks for the replys,desert rider, i dont think honda will talk to me, they probably wished they would of built the bike im doing,as there are a lot of people doing them.aevald, the concern is safety, i wasnt sure if it really needed to be done because im not going to be putting alot of heat back into the frame or parts and i dont know how rewelding (old part of frame) with new parts was going to effect strength. Basically im cutting out the lower engine cradle and reconnecting at end of the square tubing back to the main frame,so im only welding in a remote area. I will call around to some treaters see if i can find out more info and cost.             Again thanks for the input.
Reply:The folks at www.servicehonda.com might know something about it.MM350P/Python/Q300MM175/Q300DialarcHFHTP MIG200PowCon300SMHypertherm380ThermalArc185Purox oaF350CrewCab4x4LoadNGo utilitybedBobcat250XMT304/Optima/SpoolmaticSuitcase12RC/Q300Suitcase8RC/Q400Passport/Q300Smith op
Reply:They are the reason im doing my own frame,their way way overpriced and shody fit up work.
Reply:Originally Posted by mxdoggerThey are the reason im doing my own frame,their way way overpriced and shody fit up work.
Reply:I recently spoke with another frame builder about this process, he has done the research,talking with treaters and engineers. The conclusion they came up with was to not heat treat,do to the heating procees may tweak the frame and not make it any stronger. This frame conversion is  a very limited amount of work as stated before. Very unlike the process it took to produce the frame. There are alot of other same conversions done with no structural problems arising as long as the welding is good to begin with.                          I would like to thank everyone for their input and to anyone else who would like to chime in , please do