Heat Treating!?!?!

[edgar_kx3]

well since i have had problems with my 500af cracking frames! i was wondering if anybody does any heat treating with there frames? and if so how do you go about it? heat it and cool quick or heat and cool slow???

[dangerous dean]

heat and cool slowly

[edgar_kx3]

what kind of temps do i need to get the frame too before cooling???

[Motorrad]

way I have always done it is to heat.... then toss in a bucket of oil...

cooling slowly will UN harden the parts.. (IE when you have to machine a hardened part, you heat the snot out of it, throw in a bucket of sand for till it cools... machine.... reharden)

Rapid cool= harder on rockwell scale
Slow cool = softer on rockwell scale (less brittle)

alum is near impossible to get right for the home annealer...  entirely too many factors..

[Larry Wiechman]

alum is near impossible to get right for the home annealer...  entirely too many factors..

 Edgar,
  That's the best advice anyone could give.
 The first step would be to find what alloy and temper your dealing with. I doubt if few outside the factory really know.
 Are the cracks in a heat affected zone near a weld?
 Google "solution heat treat aluminum" and you'll see that this is not a simple fix.
 
Larry
 

[barryadam]

With solution annealing, you should consider a fixture to hold the critical dimensions.

A better solution (no pun intended), if cracking at welds is a problem, see a skilled aluminum welder for a better weld.  He might even suggest a localized HT so as not to affect the frame geometry.

[edgar_kx3]

ah i dunno, hoping it was the AL i used, it was a softer AL. I have gotten a piece of 6061 square stock, goin to mill the ends down and slide it into each end of frame! try to get some pics when i redo it....as for heat treating that is still in the air...talked to one guy said he sent his to service and they heat treated his?!?!? dunno if thats true or not, maybe worth lookin into.....if aj is out there let me know on that!!

Also i have a kx 250af i built and the same guy welded it, i have riden it for over 6 months and it hasnt showed a trick!!

[cigar]

There are many factors that can cause cracking of aluminium weldments. Joining incompatable alloys, incorrect filler rod selection etc. Post weld heat treatment might help but that depends on using filler alloys that are themselves heat treatable or if using something like 4043 filler rods then adequate dilution of the filler material by the base metal is necessary for the weld area to take on some of the properties of the base metal so it responds to heat treatment.

Personally I wouldn't bother with heat treatment. More importantly consult a filler rod selection chart to determine the correct filler rods to use for the types of aluminium alloys you are attempting to join. Proper welding techniques and correct filler rod selection 'might' solve your cracking problem.
 

[BDI]

I was told by the guys at http://www.bbrmotorsports.com/Home/Home.aspx?s=true that stock frames were 7005 and that I should have no problems moding one if done correctly. BBR's frames are all heat treated to 6061, If I was going to heat treat a frame i would pay to have it done professionaly. If you are haveing problems with your frame cracking I would take a seriouse look at my methods of modification.