6000 series is alloyed primarily with Magnesium and Silicon. Usual range of strengths are in the range of 300MPa yield. 7000 series is primarily alloyed with Zinc, Magnesium, Silicon and Copper. Usual range of strengths are 480-550MPa yield.

6000 is tougher, and far easier to weld. However both need proper heat-treatment after welding to restore strength to the weld zone.

Either the mods should lock this thread down like they with others Hank has been involved with or lock him out. The mods on this forum are inconsistent. There is no reason we all should be derailed by Hank's foolish behavior. It is contrary to of the DISRUPTION portion of this forum's guidelines. Why have rule if they are not followed?

I suspect Hank Rearden has contributed more to this thread than most are aware of.

If you can't handle the hardship of reading carefully, typing carefully, and thinking critically, there are two other easy options you may choose: 1) Don't get emotionally involved with an internet discussion board or 2) use the ignore button.

As Hank would say, not true (without presenting any facts to back myself up).

It isn't a matter of handling anything. If the mods don't control Hank or me, I and others have alternative forums to be involved with. No emotions at all. If I can't get some worthy discussion regarding frame material on this forum (I should), I know I can elsewhere, and I willl. I persume the mods of this forum would like good discussion regarding frame material and not have it disrupted and degrading into pissing matches. That is why the disruption clause is in the guidelines.

BTW, the ignore button makes swiss cheese out of a three page thread if I were to ignore Hank.

The best and most detailed series of articles on the topic
 

http://www.bohemianbicycles.com/materials%20science.htm


I wouldn't really talk about this subject before reading that series of articles.

I've seen that one around a number of places. It's an excellent, and not too impenetrable approach to materials for most cyclists. Some of its a little sensationalist, and a few statements aren't quite right, but otherwise, I liked it the first time I read it.

So scandium makes the welds stronger, as strong as the alloy frame material.
However, isn't it also put in the frame alloy as well? If so, what is the point of being in the frame material and not just in the welds?

Here is what Salsa has on their website:

With Scandium tubing, frame engineers are able to use smaller diameter tubes, thinner cross sections, and shaped tubes to tune the ride characteristics of each frame while using less material.
Scandium frame tubing also has increased fatigue life and improved failure modes when compared to traditional aluminum frame tubing

Yes, it is. The reason is simple. You do not weld stainless steel with mild steel filler wire, and if you want a homogeneous bike frame, you do not weld a tube with a disimilar filler. This is exactly the reason I am unhappy with Reynolds' approach to 953. They have made that mistake, and it demonstrates they don't know what they're doing.
In the case of Sc alloyed aluminium alloys, you add Sc to the tube to ensure there's no weld-pool dilution of the alloyed filler wire with parent metal, to below the point it has any effect. You don't alloy the tube for the tube's sake, you alloy it for the weld's sake.


And that's just bullshot. It's about as metallurgically sound as the 'welding non-"thermophilic" steels weakens them'.

Here's a cool quote from that website:
I never knew this.

This has been a interesting discussion. If you feel that Hank is trolling then just don't answer. You must feed a troll for him to be involved. I did not say that I thought Hank was trolling I just gave a way to deal with it. I think that Hank gets very involved in his hobbies and learns as much info on the different aspects of that hobbie as he can. Yes,he does use that to push buttons sometimes but a lot of it is misunderstanding. I could be totally wrong on this but it sounds good.

For those of you who don't not understand that metals deform by dislocation glide, please skip to the last paragraph :)

The fun bit about fatigue is that is is intrinsically linked to crystallographic orientation. Perfect metals - those with a face-centred-cubic crystal structure and the maximum possible slip modes do not have a fatigue life due to the ease with whihc you can deform them: It doen't matter what defomation vector or combination of vectors are applied, they will continue to platically deform until the materil runs out of dislocations.

Hexagonal metals, and body-centred cubic metals have a defined fatigue life because below certain dislocation glide stresses, the dislocations present within the metal will not budge. Either they are locked by having a limited number of directions they can move through the metallic lattice or insufficient stress to activate them has been applied.

Hexagonal metals have limited dislocation directions, but low activation stresses, body-centred-cubic metals have high activation stresses below certain temperatures, and limited dislocation directions. As an aside, this is what makes ferritic steels brittle at cryogenic temperatures.

Skip to: Magnesium also has a fatigue life, no matter what that article says. It's hexagonal, with a high c/a ratio. It's just a very low stress limit fatigue life.

Thanks Falanx - brilliant comments!

Once again, great information.
How about Gunnar frames with OS2 butted tube sets, featuring True Temper OX Platinum air-hardening steel alloys? I believe they used to use 953?
Falanx- what do you think is the best material for a mountain bike frame over the long haul?

I have always preferred cromoly frames, until I purchased a Cannondale with a 7005 aluminum frame.

I rode that bike into the ground, and never had a problem with it. It survived through numerous crashes and wrecks, constant bashing, and large drops.

My new bike has a 7005 aluminum frame, and I feel perfectly confident in it.

Would it be possible for a frame to be made without any welds? Just one big tubeset? Like a mold? Would it not be stronger that way?

Steel. End of.

OX Platinum will have been used in place of 853, not 953. There's a factor of two difference in price of tubeset, if not more.

What, like Trek's OCLV carbon ones?

Or in metals? Only titanium alloys are capable of being superformed by superplastic means to perform jobs such as this, but the tooling costs would be Biblical. Aluminium-lithium alloys can be superplastically formed, but they are too brittle, as far as I am concerned, for bike frames. Plane skins, yes, even parts of the superstructure, but by the time you've rammed your airplane into something, it's too late, so you wouldn't worry about impact toughness :)

In short? No, not really, unless the frame was laid up in some way.

However! For some time I have been considering the use of ultra-high-strength metallic whisker fibres in a low density alloy matrix, such as perhaps iron whiskers in an Al/Mg matrix. Now that would eb something to see. You're looking at about 30 grand a frame though :)

Falanx--
Being old fashioned, I am going with a hard tail for my new frame. Being even more old fashioned, I think I am going with steel. My brother loves his Gunnar Rockhound. You have any comments on their switch from 853 to OX Platinum? Also looking at the Jamis Dragon.
Thanks

No difference. The alloys are almost identical in both metallurgy and thermomechanical processing. I should imagine the reason they changed is more to do with securing shipments in an acceptable time frame, price of materials and quality control. As a general rule, and Reynolds are likely to get miffed at me here, True Temper steel is more consistent :)

Falanx, thanks for sticking with this thread. I'm learning a ton. If you don't mind one more question, what do you think of Columbus Zona and Columbus tubing in general compared to the popular offerings such as True Temper and Reynolds? Also, does triangulating the tubes, like Marin does, make them any more durable?

Thanks again Falanx. This is the most interesting thread I have ever seen in this forum.
Here is a reponse from a company that makes Sc frames.

Okay...well we are using it in practice and have found it to be quite
true. Our 29 inch is the best example. You just simply couldn't do a
pivotless softail from regular aluminum tubing. It would tear like the
pop can effect. We have also seen off the charts test results on our
scandium stems in direct comparrison to aluminum samples of the same
construction. Believe it or not..scandium is a real deal material. Its
always up to you to decide what you buy. If scandiums not for
you...then its just not fo you. Hope you find something that fits your
riding and research.

(Been a while since I've chimed in . . . been on a mini-vacation and away from the computer.) Don't get me wrong, 66, I love my job. I get to both write/edit and do graphic design work; so I get to carry a printed piece from start to finish. Much more gratifying than just being a production artist like I was years ago. We've also been blessed enough to be able to buy rural property we could afford and design (my old HS architecture skills) and build our 'dream house' on it from the foundation up (ourselves - no subs).

When I was in college, I missed having access to a metal shop so much I enrolled in an Ag Mech lab just so I could weld, mill and run a lathe again.

Since then, there are days when I really wish the metalworking part of my shop was more fleshed out. My old stick welder and oxy-acet tanks look a little lonely. I'm still holding out hope for 'someday' on the Bridgeport; but before that even, I think I'd like a forge :D