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7005 vs 6061(4 posts)

7005 vs 6061niteschaos
Jul 16, 2002 8:20 AM
I here a lot of high end manufactures using either of these two, or just claiming frame made from either 7000 series or 6000 series Al. What are the pros and cons of each? My Felt is made from 7005, but I read that Cannondale makes theirs from 6061-T5. What is the advantages of each alloy over the other?
re: 7005 vs 6061No_sprint
Jul 16, 2002 10:03 AM
Put overly simply, the 7005 alloy is a touch stronger, therefore, can be made into slightly thinner tubes making it slightly lighter. Each can be treated in many different ways and both can be T5. I would say that to try to name distinct advantages of one over the other would be splitting hairs. My 7005 bike is T6 Energy and triple butted I think.
re: 7005 vs 6061eddie m
Jul 16, 2002 10:13 AM
6061 is a common aluminum alloy. T5 is a solution heat treatment that increase the strength witout changing the elasticity of the material. Heat treatment of 6061 frames is probably done after welding. T6 is the strongest heat reatment, but maybe T5 is used to avoid warping the frames after welding. 7005 is a different alloy. 7000 series alloys are generally stronger than 6000 series, but all aluminum alloys have the same elastocity and density. Some 7000 series frames are not heat treated after welding (the tubes may be heat treated before) because the material does not lose as much strength in welding. Scandium is another aluminum alloy. I don't know if "scandium" is a proprietary name or an actual element in the alloy. It's about 10% stronger than other aluminum alloys. Aluminum is lighter than titanium but much weaker. It also is subject to fatigue failures without much obvious warning. (A steel bike would sag but be rideable for miles before it actually broke from fatigue.) I think the reason some riders dislike alumin frames is that,in order to insure long life, the frames are built stronger than they need to be for optimum riding characteristics. Aluminum is easy to fabricate and a good material for specialized bikes, as for important races where light weight is most important and where long life is not a concern.
re: 7005 vs 6061Nessism
Jul 16, 2002 10:43 AM
From what I understand 7005 needs to be "aged" after welding to bring the metal back up to full strength. Somehow the strength increases in the weld area by itself after a few weeks which is one of the major benifits of this alloy. To speed up the process, the frame can be artifically aged - basically heat treated.

6000 series Al requires a more elaberate heat treatment process involving heating, quenching (dunking in water while hot), and prolonged aging to achive T6 status. Also, I don't think 6000 series metals will harden on their own within any reasonable time frame thus making heat treatment a must.