simontemplar

Can anyone tell me what the difference is between a 6000 series alloy and a 7000 series ? thanks.

texascyclist

7000 series has better tensile strength and fatigue life. That means that it can take more pull without breaking and take a higher number of pulls.

BTW, there is nothing wrong with 6000 series. I have a bike made of 6061 and it's a great ride that's less than 18lb including my cages, bag, pedals, and rear light. I take pride in there not being a single piece of carbon on the thing.

Don't listen to any garbage generalizing the ride of a bike made of 6000 series vs 7000 series. That's all based on design.

6061 T6 specs: (40ksi tensile strength, 14ksi fatigue strength)
https://www.matweb.com/search/Specifi...ssnum=MA6061T6
7005 T6 specs: (50.8ksi tens str, 21.8ksi fatigue str)
https://www.matweb.com/search/Specifi...ssnum=MA7005T6

For steel, you have a definite fatigue strength where the thing will last forever. For AL, there is no such thing, so they pick a number of cycles and determine what stress will cause the part to break at that number of cycles and you have your "fatigue strength". Aluminum does not have an infinite fatigue strength, that's why AL airplanes have to retire eventually because the fatigue life of the material requires it.

sydney

Why don't you google it and get a straight answer rather than BS? Short story is that after welding and more extensive higher temp heattreating,6xxx is said to produce a superior longer lived frame.

DannoXYZ 

Where'd you get that info?

Nessism

6061 aluminum is a medium strength grade alloy that has good ductility so it's less likely to crack than some other alloys. Drawback is that it requires a fairly involved heat treatment to reach full strength. This alloy is quite versitale as well since it can be forged as well as extruded. It's also weldable.

7005 series is similar in strength to 6000 series but does not need extensive heat treatment - it hardens with age. This is a good alloy but seems to be more prone to cracking than 6000 series. Again, weldable.

7075 is a completly different alloy than 7005. It's quite a bit stronger than 6061/7005 but can't be welded. Good stuff for bars and stems.

Hope this helps.

Ed

texascyclist

Try the links. Matweb is a really good site for materials.

Avalanche325

But the trick is the 6061 is heat treated. That's the T6 in 6061 -T6.

texascyclist

yeah, if it was T0 (no heat treat), it wouldn't be worth much at all.

texascyclist

Is my answer BS?

sydney

Yes.....^^^

Avalanche325

True. The welds would more than likely break.

texascyclist

Please explain.