What kind of frame material is this?



zoolander

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Sep 19, 2007
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Anybody ever heard of a frame material of Scandium?
Someone i know has a Rocky Mountain road bike for sale and the frame is supposedly made of this.
 

threaded

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Jul 6, 2006
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zoolander said:
Anybody ever heard of a frame material of Scandium?
Someone i know has a Rocky Mountain road bike for sale and the frame is supposedly made of this.
Well, it will not be pure Scandium, just some added in to a mix for an Aluminium alloy. Aluminium alloys are generally a pig to weld, and the alloys that can be welded easily aren't all that strong. Add a little Scandium to the alloy though, and as if by majyk, you get a strong alloy that can be welded.
 

lbraasch

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Jul 24, 2007
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zoolander said:
so basically it is an alum framed bike?
not quite. It's stronger than aluminum, and is also lighter, however I believe it's supposed to have ride characteristics of aluminum. Fairly popular material for Lacrosse shafts.
 

zoolander

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Sep 19, 2007
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have you guys ever seen many bikes made of this material?What brands?Is it supposed to be any good?
 

grv

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Jun 8, 2006
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zoolander said:
have you guys ever seen many bikes made of this material?What brands?Is it supposed to be any good?
Salsa uses this in some of their frames like the Campeon, which I have heard good things about. I don't own one, so I can't say first hand what it's like. Here's their blurb:

http://www.salsacycles.com/materials.html
 

zoolander

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Sep 19, 2007
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Scotty...i tried google and the only thing i could find on the bike brand im looking at(used) was for mtn bikes,not a road bike
 

dhk2

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Aug 8, 2006
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zoolander said:
Scotty...i tried google and the only thing i could find on the bike brand im looking at(used) was for mtn bikes,not a road bike
Scandium used to be a big marketing deal when it was new maybe 10 years ago. AFAIK, it's a 7005-series aluminum. Scandium is an alloying element added in very small % amounts to the aluminum to improve grain structure and ability to withstand heat of welding. All 7005 series aluminum contains alloying elements like these to improve grain structure; these are responsible for the improved strength and fatigue life. IIRC, standard elements are Mg, Mn, Cu....you can google "7005 aluminum" and read up on the specs.

In theory, scandium aluminum may have a slight strength improvement over standard 7005 aluminum, so in theory a framebuilder could use thinner/lighter-walled tubing with equivalent strength and fatigue-life. IMO, it's more important to get the tube dimensions and wall thickness (eg frame weight) appropriate to your riding and goals than to be concerned about the micro-alloying elements the tubing contains.
 

alienator

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Jun 10, 2004
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dhk2 said:
Scandium used to be a big marketing deal when it was new maybe 10 years ago. AFAIK, it's a 7005-series aluminum. Scandium is an alloying element added in very small % amounts to the aluminum to improve grain structure and ability to withstand heat of welding. All 7005 series aluminum contains alloying elements like these to improve grain structure; these are responsible for the improved strength and fatigue life. IIRC, standard elements are Mg, Mn, Cu....you can google "7005 aluminum" and read up on the specs.

In theory, scandium aluminum may have a slight strength improvement over standard 7005 aluminum, so in theory a framebuilder could use thinner/lighter-walled tubing with equivalent strength and fatigue-life. IMO, it's more important to get the tube dimensions and wall thickness (eg frame weight) appropriate to your riding and goals than to be concerned about the micro-alloying elements the tubing contains.

Yup. What he said: it's added to improve strength in welded joints. Outside of that, it's nothing special. It does sound cool in an advert, much like Easton's "nanotechnology." Alas, the marketing hooplah falls well short of the physical reality.....
 

CAMPYBOB

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Sep 12, 2005
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Scandium adds strenth to aluminum. Strength is a good thing to have in a bicycle frame.

Scyield.gif


Scandium makes for welds less prone to failure from grain crystalization:

"The Al-Sc phase diagram below shows the Al-Al3Sc eutectic reaction to take place at an unusually high temperature. This high solidification temperature improves heterogeneous nucleation of grains, resulting in a refined grain size (and reduced hot cracking). A reduction in hot cracking is especially important for welding of high strength alloys. Most of the highest strength aluminum alloys are not weldable and the the addition of Sc can improve the weldability of many of these alloys."


[size=+1] Element[/size][size=+1]Recrystallization Temp. (C)[/size]Mn 325Cr325Zr400Sc600


scphase.gif


If a "correct" tube shape is more desireable, scandium also improves the workability of the tube by mechanical processes.

"Perhaps a more important aspect of the greater thermal stability of the Al3Sc dispersoids is their effectiveness at reducing recrystallization. Alloys that are heavily cold worked (such as extruded and/or drawn bats, bike frames, and tubes) contain sufficient stored energy to cause recrystallization. This results in substantial strength loss. Designers know that thin-walled products have less strength than thicker sections due to this softening effect. The addition of Sc can eliminate this problem in many combinations of alloy, heat treatment, and mechanical working."

I guess my question would be is why would anyone want an aluminum frame that is manufactured without scandium as an alloying agent?
 

dhk2

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Aug 8, 2006
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CB, I'm no metallurgist, and have never understood the "eutectic point". But forgive me for being skeptical of your quoted material. Could you provide your reference please? In particular, the declaration that "Sc can eliminate this problem...." sounds like ad copy to me.

If the addition of Sc was really a big deal, believe we'd have a new series of Al to describe it, and it would be widely used by Columbus and every other leading maker of aluminum tubesets for frames. When I was shopping for frame tubing in 2003, Easton was the only maker I recall having "scandium"; perhaps there are others now.

I was under the impression that the "artificial aging" as specified by the 7005 series tube maker (after welding) is sufficient to stabilize the grain structure if the frame builder does it properly. At any rate, believe the cited advantages to Sc addition are insignificant compared to the shape, size and wall thickness choices that a framebuilder makes.
 

CAMPYBOB

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Sep 12, 2005
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See the link i furnished earlier. There's plenty more info available using google.

Basically, scandium adds strength to aluminum, aids in the shaping and cold working of aluminum and it reduces grain crystalization at the welds. It also yields a finer grain structure which generally (all things being equal) results in less cracking along grain boundaries.

Therefore, it aids in tube shaping. Aids in welding. Allows a thinner, lighter tube (less mass) to be used for the same resulting strength or a same gauge tube that is stronger.

Yes. I agree. It's next to worthless.
 

ScienceIsCool

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Jun 25, 2006
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The reason it's been nicknamed Scam-dium is because it is rare and expensive, so some manufacturers have been guilty of using far less than is necessary to see the most benefit.

That said, I have no data whatsoever on the various tubesets, how much Sc they contain, or the relative benefit.

If I was in the market for a new frame, I would definitely research and consider a Scandium alloyed aluminum frame.

John Swanson
www.bikephysics.com