# Aluminum - what are the differences?



## singletrak (Mar 29, 2005)

Can anyone explain the differences between 6000 series aluminum (Trek's "Alpha Black used in the XO's) vs. 7005 aluminum (used in the Felt cx bikes) vs. Dedacciai Deda EM2 (used in the Stevens Super Prestige frame)?

Thank you in advance for any input.


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## the mayor (Jul 8, 2004)

Look Here


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## singletrak (Mar 29, 2005)

Thanks . Just asked a simple question. No need for sarcasm. If that's all you have to offer don't waste our time.


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## pretender (Sep 18, 2007)

I think I'll waste even more electrons.


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## singletrak (Mar 29, 2005)

.....


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## OnTheRivet (Sep 3, 2004)

singletrak said:


> Can anyone explain the differences between 6000 series aluminum (Trek's "Alpha Black used in the XO's) vs. 7005 aluminum (used in the Felt cx bikes) vs. Dedacciai Deda EM2 (used in the Stevens Super Prestige frame)?
> 
> Thank you in advance for any input.


In the grand scheme of things there is very little difference in the final product. Some are cheaper initially but require more involved heat treating after the fact etc. When looking at aluminum frames what particular alloy it's made of is of little consequence.


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## BentChainring (Jun 23, 2005)

To the bike manufacture, Reynolds suggests that both 6061 and 7005 are to be post weld heat treated. Per Reynolds, 6061 is to be BOTH solution heat treated and aged. While 7005 is only aged.

Without getting into the details, the solution heat treatment is more expensive, since you require a furnace, as opposed to an oven (you can age 7005 in a home oven). This makes it a bit cheaper, if your actually doing the post weld heat treatment (some metallurgist friends and I wonder if they do anything at all.)

That and 7005 is a tad stronger, and MUCH more susceptible to stress corrosion cracking 

YMMV.


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## roseyscot (Jan 30, 2005)

singletrak said:


> Thanks . Just asked a simple question. No need for sarcasm. If that's all you have to offer don't waste our time.


he's a crotchety man who enjoys being crotchety so excuse his attempt at humor. i think it is a valid question especially with the examples of 'cross frames you referenced.


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## singletrak (Mar 29, 2005)

Thanks man, that's all I was asking for. So the differences between aluminums are minor and not like the major differences between matrials like steel and cf. 

The inquiry stems from the fact I'm looking at getting a second cross frame. I really like cf bikes. I've had 4 cf bikes none of which were crossers. My current cross bike is 7005 aluminum and the bike I'm looking at is available in cf or Dedacciai Deda EM2 aluminum.

If there's really no difference than I'll give more consideration to the cf.


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## BentChainring (Jun 23, 2005)

singletrak said:


> Thanks man, that's all I was asking for. So the differences between aluminums are minor and not like the major differences between matrials like steel and cf.
> 
> The inquiry stems from the fact I'm looking at getting a second cross frame. I really like cf bikes. I've had 4 cf bikes none of which were crossers. My current cross bike is 7005 aluminum and the bike I'm looking at is available in cf or Dedacciai Deda EM2 aluminum.
> 
> If there's really no difference than I'll give more consideration to the cf.



Yes, I would say that the differences between a 6061 and 7005 AA frame are imperceptible.


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## the mayor (Jul 8, 2004)

roseyscot said:


> he's a crotchety man who enjoys being crotchety


Damn Straight!!


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## the mayor (Jul 8, 2004)

BentChainring said:


> Yes, I would say that the differences between a 6061 and 7005 AA frame are imperceptible.


Agreed...
But, think about this:
A frames is advertised as " insert tubing name here", and has a sticker stating that. But how do you know it really is that tubing? 

And how do you know all the tubes on the frame are that spec? ( many times,they are not)

Digest....


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## suspectdevice (Feb 2, 2008)

It's not the alloy (well 7005 does suck, it's corrosion issues are a pretty big deal), it's the profiles of the tubing. Just like steel or ti, the difference in ride between various frames is all down to the tubing diameters and butt profiles. Just like cooking with Margarine or Butter, it's how much you use. A good chef makes good food.


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## eyefloater (Jul 3, 2006)

the mayor said:


> And how do you know all the tubes on the frame are that spec? ( many times,they are not).


To expand on this point, a lot of the time the "main triangle" will be the badged tubing and the seat/chain stays will be something beefier (straight gauge instead of butted, etc). My steel mountain bike is like but I'm fine with it ... it's just something to be aware of if you're taking marketing info at face value.


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## BentChainring (Jun 23, 2005)

suspectdevice said:


> It's not the alloy (well 7005 does suck, it's corrosion issues are a pretty big deal), it's the profiles of the tubing. Just like steel or ti, the difference in ride between various frames is all down to the tubing diameters and butt profiles. Just like cooking with Margarine or Butter, it's how much you use. A good chef makes good food.



Agreed, and while I own two Al rides, my commuter (converted specialized hardrock - 6061) and my mtb (Salsa Caballero - Al-Sc alloy), I think aluminum is not the greatest material to build space frames from. It works pretty well, but other materials lend themselves better to frames. IMO

Give me steel or Ti for fatigue life and strength. And carbon for Bling. :Thumbsup:


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## suspectdevice (Feb 2, 2008)

BentChainring said:


> Agreed, and while I own two Al rides, my commuter (converted specialized hardrock - 6061) and my mtb (Salsa Caballero - Al-Sc alloy), I think aluminum is not the greatest material to build space frames from. It works pretty well, but other materials lend themselves better to frames. IMO
> 
> Give me steel or Ti for fatigue life and strength. And carbon for Bling. :Thumbsup:


It's great to have an opinion. I happen to think almost any material can make a good frame. And I can build a domestic aluminum frame for hundreds of dollars cheaper than a steel of Ti frame. If someone actually understands the properties of a material, than can build a super bike out of anything....


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## BentChainring (Jun 23, 2005)

suspectdevice said:


> It's great to have an opinion. I happen to think almost any material can make a good frame. And I can build a domestic aluminum frame for hundreds of dollars cheaper than a steel of Ti frame. If someone actually understands the properties of a material, than can build a super bike out of anything....


Agreed. My concern with Al is fatigue life. While you can obtain virtually infinite High Cycle Fatigue properties from Steel and Ti, Aluminum will always be limited due to the nature of the FCC crystal structure.

IMO, I believe fatigue life is where it matters, you can always find a welder to join thinner and thinner tubing, but the limit comes when you attempt to design a stiff frame out of aluminum you can design an optimized frame, which will fail in HCF. That being said, I still ride Al frames 

Just for reference, the _Specific Stiffness_ of the common bike frame materials is similar:
Material.....Stiffness......Density.................Sp. Stiffness
Steel ------- 30Msi------0.284 lb/in^3--------------105
Ti-------------16Msi------0.162 lb/in^3-------------- 98
Al-------------10Msi------0.098 lb/in^3--------------102
Mg----------- 6.5Msi-----0.066 lb/in^3-------------- 98
Carbon- Im too lazy to go look up properties, but its ~ 200

So for an identical stiffness frame, made out of any of the 4 Metals above, you will have a _very_ similar frame weight (ignoring HCF). Carbon is a different animal HCF wise, but you can see why a Carbon frame can be made lighter than a similar stiffness metallic frame.

Oh, and for reference, my preferred frame material (if I can find tubing, and a clean room that I can weld it in) 

Beryllium---41Msi--------0.066 lb/in^3---------* 621* 

Cheers


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## bikerb (Oct 7, 2003)

BentChainring said:


> Agreed. My concern with Al is fatigue life. While you can obtain virtually infinite High Cycle Fatigue properties from Steel and Ti, Aluminum will always be limited due to the nature of the FCC crystal structure.
> 
> IMO, I believe fatigue life is where it matters, you can always find a welder to join thinner and thinner tubing, but the limit comes when you attempt to design a stiff frame out of aluminum you can design an optimized frame, which will fail in HCF. That being said, I still ride Al frames
> 
> ...


Just remember not do breathe while you weld it. And hope you never crash it. Have you looked at its ductility too?


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## Tweezak (Dec 6, 2008)

I didn't see anyone mention scandium (except for the mtb frame mentioned) so I'll chime in. I'm no expert but I was recently trying to decide on a frame and looked into scandium.

Technically, scandium is just something that is alloyed with aluminum to make it possible to weld grades of aluminum that otherwise do not lend themselves well to welding. I think some of the 7000 series aluminums fall into this category. So, if you are considering a 7000 series frame, you may want to look for something that is alloyed with scandium.

Here's a blurb from wikipedia on the subject:
When added to aluminium, scandium substantially lowers the rate of recrystallization and associated grain-growth in weld heat-affected zones. Aluminium, being a face-centred cubic metal, is not particularly subject to the strengthening effects of the decrease in grain diameter. However, the presence of fine dispersions of Al3Sc does increase strength by a small measure, much as any other precipitate system in aluminium alloys. It is added to aluminium alloys primarily to control otherwise excessive grain growth in the heat-affected zone of weldable structural aluminium alloys, which gives two knock-on effects; greater strengthening via finer precipitation of other alloying elements and by reducing the precipitate-free zones that normally exist at the grain boundaries of age-hardening aluminium alloys.


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## OnTheRivet (Sep 3, 2004)

BentChainring said:


> So for an identical stiffness frame, made out of any of the 4 Metals above, you will have a _very_ similar frame weight


The kicker here is, with steel it's Achilles heel is it's density. To create a steel frame that approaches the weight of a light Aluminum frame the tubes become ridiculously thin. They may not have the fatigue issues that Al has but their impact resistance is very poor.


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## BentChainring (Jun 23, 2005)

OnTheRivet said:


> The kicker here is, with steel it's Achilles heel is it's density. To create a steel frame that approaches the weight of a light Aluminum frame the tubes become ridiculously thin. They may not have the fatigue issues that Al has but their impact resistance is very poor.


Bingo, there are "other factors" other than just the specific stiffness, HCF and "dent resistance".

I like Steel and Ti, other frame materials can work perfectly well. Just one metallurgists opinion. :thumbsup:

nK


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## singletrak (Mar 29, 2005)

So what's Dedacciai Deda EM2 ? Just a fancy name for a 6000 or 7000 aluminum alloy?


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## dave2pvd (Oct 15, 2007)

Of course, you have to remember that a well designed Alu frame may never see excessive stress in normal use.....so, theoretically, there are many aluminum frames out there that you could get on and ride right now and will not CATASTROPHICALLY FAIL eek: ) for, oh, maybe 1,000 years.


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## exmime (Aug 18, 2007)

*hyrafromed materials*

The Power of Googleedacciai Deda EM2
(CSK had a new track bike on display made of Dedacciai 7003 Aluminum. ... The frame features Deda EM2 Hydraform tubing combined with a Dedaciai rear end. ...)
Looks like 7003, which is hydraformed, hydraformed tubes are cool looking, has anyone seen it done with steel or ti or would that cause metallurgical fatigue to those materials


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## Coolhand (Jul 28, 2002)

For cross:

playing with others' money: Ti

playing with my money: Al or maybe Carbon. Spend your money on tubular wheels and nice tubbies first IMHO. And Paul's Neo Retros.


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## carlhulit (Nov 5, 2005)

steel does not have major fatigue advantages in bike frames, to be bellow the fatigue limit on a steel bike would be a 6 lb+ frame. buy it cause you like the ride or the looks, but know lightweight and durable dont go together when it comes to frames


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## pretender (Sep 18, 2007)

carlhulit said:


> steel does not have major fatigue advantages in bike frames, to be bellow the fatigue limit on a steel bike would be a 6 lb+ frame. buy it cause you like the ride or the looks, but know lightweight and durable dont go together when it comes to frames


Mode of failure is another issue.


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