Advertise on Bikeforums.net



User Tag List

Page 1 of 2 12 LastLast
Results 1 to 25 of 37
  1. #1
    Banned
    Join Date
    Oct 2006
    Posts
    2,296
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Material durability

    Which frame material is the most durable?

    Folks always talk about which is lighter, which is stronger, etc, but which is the most corrosion resistant? Which is the more abrasion resistant?

    Titanium? Aluminum? Carbon? Steel?

  2. #2
    cs1
    cs1 is offline
    Senior Member cs1's Avatar
    Join Date
    Feb 2004
    Location
    Clev Oh
    My Bikes
    Specialized, Schwinn
    Posts
    6,187
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by makeinu View Post
    Which frame material is the most durable?

    Folks always talk about which is lighter, which is stronger, etc, but which is the most corrosion resistant? Which is the more abrasion resistant?

    Titanium? Aluminum? Carbon? Steel?
    For some reason I never thought of abrasion resistance as an important quality in a bicycle. Why do you ask?

    Tim
    1999 Waterford RSE-11, 1995 Waterford 1200, 1989 Specialized Rockhopper Comp
    1989 Raleigh Technium, 1989 Schwinn Traveler, 1986 Specialized Rockhopper
    1984 Specialized Stumpjumper, 1986 Specialized Stumpjumper and just way too many projects to list.

  3. #3
    Banned
    Join Date
    Aug 2005
    Posts
    5,117
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I never really thought about it either, though there was that Ti bike a while back that was worn through a tube by mud/tire action.

    I think the problem with this question is:

    A) Materials vary less than one might think since builders optimize the strength to some extent. A Ti bike that was made to the same weight as a steel one would be plenty rugged, but not a common animal.

    B) Once you introduce 2 or 3 strength measures it isn't going to yield a clear winner. Like Carbon is strong for cycles to failure but not crushing, at least not as commonly made. Composites anyone?

    C) It depends how much you want. Like steel is corrosion resistant within the needs of most cycling, but not so good where marine levels of corrosion are concerned. There is likely to be some stuff on a bike that is plain steel anyway, so how much more corrosion resistant than that do you need.

    D) How far are you willing to go? If this was a serious milspec kind of test we might find these materials present with coatings far more advanced than what we see in the average bike. What about a hard anodized Al frame or Teflon coated steel. Both these materials get used in military enviros, so they are rugged in the right applications. Ti's price has limited it's widespread adoption, so it is hard to see it purely in structural terms.

    My guess is that Ti is the most corrosion and erosion resistant, but it is often paper thin. For every day cycling Al is pretty corrosion resistant, you need something like a penny and some salt water to really get it bubbling. It isn't terribly erosion resistant, but it is the thickest, and fattest to start with. Steel is very good on erosion and not wonderful on corrosion. The later can be improved with coatings, and as mentioned the tubes may not be the weak link.

  4. #4
    Decrepit Member Scooper's Avatar
    Join Date
    Aug 2005
    Location
    San Francisco California
    My Bikes
    2007 Waterford 953 RS-22
    Posts
    8,613
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Peterpan1 View Post
    Steel is very good on erosion and not wonderful on corrosion. The later can be improved with coatings, and as mentioned the tubes may not be the weak link.
    Don't forget Reynolds 953 (maraging stainless steel) and Columbus XCr (martensitic stainless steel). Admittedly they're both relatively new and don't have a long track record yet, but both have the corrosion resistance of stainless steel.
    Last edited by Scooper; 01-15-08 at 03:38 PM.
    - Stan

  5. #5
    Senior Member Nessism's Avatar
    Join Date
    Jun 2004
    Location
    Torrance, CA
    My Bikes
    Homebuilt steel
    Posts
    2,324
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    It’s not strictly a matter of the material so much as how the material is used. For example, a thin walled frame will see higher stress than a frame with thick tubes. From a corrosion standpoint, the coating process makes a difference. The joining process is critical as well; properly executed welds are critical and I suspect, more durable than bonded joints.

    In a general sense I’d say that welded Ti is going to near the top of the durability scale since it has a high fatigue limit and does not corrode in any meaningful way. Steel also has a high fatigue limit but corrosion can be an issue depending on how the frame is treated. Aluminum has no fatigue limit thus it is prone to cracking. Carbon is prone to impact damage, UV aging, bonded joint failure, and other things I’m sure. Not saying carbon is bad, but I couldn’t put it in the same durability class as Ti or steel.
    Becareful buying/selling bike parts on-line. I learned the hard way. :(

    Good/Bad Trader Listing

  6. #6
    Newbie
    Join Date
    Jan 2008
    Posts
    2
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Carbon isnt as impact intolerant as the old myth that gets peddled round still 10 years ago when we were fiddling with thermoplastics in bikes it was tough now its even tougher to the point where bullets wont go through it the problem is that you cant really have your cake and eat it and it doesnt build nice lightweight bikes as peterpan1 states its not something which is cost effective in the bike world

    Bonded joints easily match welded joints in many applications the problem is more that people dont know how to bond properly or engineer (if its worth it) a joint properly, in the case of bicycle frames the economics has a large impact on the joint design and often makes it a poor choice in terms of the public slating it receives for failing

    mud is an abrasive and no different to any abrasive grinding media due to the fact its a hard particulate suspended in a liquid and even the hardest metals are ground due to it being an effective way to reduce ultra hard materials ,maybe get some wear plates bonded to the area which is being abraded

  7. #7
    Senior Member Nessism's Avatar
    Join Date
    Jun 2004
    Location
    Torrance, CA
    My Bikes
    Homebuilt steel
    Posts
    2,324
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by compositepro View Post
    Carbon isnt as impact intolerant as the old myth that gets peddled round still 10 years ago when we were fiddling with thermoplastics in bikes it was tough now its even tougher to the point where bullets wont go through it the problem is that you cant really have your cake and eat it and it doesnt build nice lightweight bikes as peterpan1 states its not something which is cost effective in the bike world

    Bonded joints easily match welded joints in many applications the problem is more that people dont know how to bond properly or engineer (if its worth it) a joint properly, in the case of bicycle frames the economics has a large impact on the joint design and often makes it a poor choice in terms of the public slating it receives for failing

    mud is an abrasive and no different to any abrasive grinding media due to the fact its a hard particulate suspended in a liquid and even the hardest metals are ground due to it being an effective way to reduce ultra hard materials ,maybe get some wear plates bonded to the area which is being abraded

    Sorry to sound critical but...punctuation improves readability and credibility. Yes, I am a grump. Sorry again.
    Last edited by Nessism; 01-16-08 at 07:10 AM.
    Becareful buying/selling bike parts on-line. I learned the hard way. :(

    Good/Bad Trader Listing

  8. #8
    THE Materials Oracle Falanx's Avatar
    Join Date
    Feb 2006
    Location
    Finally... home :-)
    My Bikes
    Univega Alpina 5.1 that became a 5.9, that became a road bike... DMR TrailStar custom build
    Posts
    502
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Scooper View Post
    Don't forget Reynolds 953 (maraging stainless steel) and Columbus XCr (martensitic stainless steel). Admittedly they're both relatively new and don't have a long track record yet, but both have the corrosion resistance of stainless steel.
    953 won't have awesome corrosion resistance, certainly not as good as XCR. And neither come close to plain 304 stainless.


    Back to topic:

    If framebuilding was simply a case of plain numbers, steels would win on all mechanical proerty points. Highest fracture toughness, check. Highest UTS, check. Highest elongation during failure, check. Things like density wouldn't factor for much if money was no object, as the most expensive, strongest, toughest steels hold by far and away the pinnacle of mechanical properties.

    But as any builder here will tell you it's not that simple. First and most importantly economics factor. What you can work with for the money. Coupled to that - nt many manufacturers of engineerin g materials draw tube or other bike friendly shapes, and even fewer know how to butt.

    Second - as builders here will also point out, builders are experimenters They adjust and experiment with frame materials until they first get somethign that works, then refine it to maximise the benefits inherent in any material and try to ameliorate its inherent weaknesses. As Thylacine will say, there are no bad materials, just bad designs.

    My two penn'orth remains steel :-)
    "While my father fought for you, I learnt. While my father glorified your petty administration, I learnt. While he longed every day for our line, Adunís line, to be restored, I learnt. He sent me away to bring the Dark Templar back when the time was right!
    "And you tell me that I cannot do this? That I cannot feel the weight of the universe?
    "Damn you, Tellan! Aldaris killed my father!"

  9. #9
    There's a biking season? yohannrjm's Avatar
    Join Date
    Sep 2007
    Posts
    276
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Nessism View Post
    Sorry to sound critical but...punctuation improves readability and credability. Yes, I am a grump. Sorry again.

    Errm!! (Clears throat) Correct spelling helps too.


  10. #10
    Banned
    Join Date
    Oct 2006
    Posts
    2,296
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by cs1 View Post
    For some reason I never thought of abrasion resistance as an important quality in a bicycle. Why do you ask?

    Tim
    Only because I've heard that abrasion compromises carbon fibre. I have no idea if that's true or not.

    I agree that above a certain level abrasion should not be an important quality for a bicycle frame, but does carbon fibre even attain that level?

  11. #11
    Senior Member Nessism's Avatar
    Join Date
    Jun 2004
    Location
    Torrance, CA
    My Bikes
    Homebuilt steel
    Posts
    2,324
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by yohannrjm View Post
    Errm!! (Clears throat) Correct spelling helps too.

    Agree!
    Becareful buying/selling bike parts on-line. I learned the hard way. :(

    Good/Bad Trader Listing

  12. #12
    Decrepit Member Scooper's Avatar
    Join Date
    Aug 2005
    Location
    San Francisco California
    My Bikes
    2007 Waterford 953 RS-22
    Posts
    8,613
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Falanx View Post
    953 won't have awesome corrosion resistance, certainly not as good as XCR. And neither come close to plain 304 stainless.
    Falanx, is there some way to quantify the relative corrosion resistance of 953 (which, according to the Reynolds website, has corrosion resistance superior to type 410 stainless steels).

    I can't find anything on the Columbus website about the composition of XCr, other than "This new stainless steel, developed by Aubert & Duval, the famous French steel mill, was specifically requested by the military industry, looking for a valid substitute for the cadmium plated temper hardening steels which could no longer be produced because of their highly polluting manufacturing process." ed. - Someone should teach the Italians about the use of commas and run-on sentences.

    Looking at web resources for information on corrosion resistance of stainless steels, 410 is said to combine superior wear resistance of high carbon alloys with the excellent corrosion resistance of chromium stainless steels. Grade 304 is said to have excellent corrosion resistance in a wide range of atmospheric environments and many corrosive media.

    There are lots of numbers floated for both 410 and 304, but as a layperson I haven't a clue what they mean, and since Columbus really doesn't say what type stainless is the material used in XCr, I don't know which alloy properties best represent it.

    Are there any numbers that would offer some insight into the relative corrosion resistance of these alloys?

    Thanks.
    - Stan

  13. #13
    THE Materials Oracle Falanx's Avatar
    Join Date
    Feb 2006
    Location
    Finally... home :-)
    My Bikes
    Univega Alpina 5.1 that became a 5.9, that became a road bike... DMR TrailStar custom build
    Posts
    502
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Scooper View Post
    Falanx, is there some way to quantify the relative corrosion resistance of 953 (which, according to the Reynolds website, has corrosion resistance superior to type 410 stainless steels).

    I can't find anything on the Columbus website about the composition of XCr, other than "This new stainless steel, developed by Aubert & Duval, the famous French steel mill, was specifically requested by the military industry, looking for a valid substitute for the cadmium plated temper hardening steels which could no longer be produced because of their highly polluting manufacturing process." ed. - Someone should teach the Italians about the use of commas and run-on sentences.

    Looking at web resources for information on corrosion resistance of stainless steels, 410 is said to combine superior wear resistance of high carbon alloys with the excellent corrosion resistance of chromium stainless steels. Grade 304 is said to have excellent corrosion resistance in a wide range of atmospheric environments and many corrosive media.

    There are lots of numbers floated for both 410 and 304, but as a layperson I haven't a clue what they mean, and since Columbus really doesn't say what type stainless is the material used in XCr, I don't know which alloy properties best represent it.

    Are there any numbers that would offer some insight into the relative corrosion resistance of these alloys?

    Thanks.
    Right, I'll address these simply, 'cause it's easier than getting into some long winded explanation.

    304 - resistance to all oxidising media - that's all the acids that have oxygen in them plus hydrofluoric, all alkalis and anything with a 'per' in it's chemical name. Mildly resistant to reducing media - that's acids without oxygen in them and most ionic binary compounds of same. 18% chromium providesd general corrosion resistance and good resistance to oxidisers, 8-10% nickel content provides resistance to reducing media and keeps the alloy austenitic.

    410 - not as resistant to any media as 304. Contains no nickel and is martenistic, so is susceptible to hydrogen embrittlement, too.

    953 - Made from an alloy called Carpenter Custom 455. Not as corrosion resistant as 304. In forgings more corrosion resistant than 410. In welded structures no-one knows, but extremely unlikely to be as good as forged. Heat affected zones and variable precipitate density, distribution, dimensions and alterations in chemistry across the HAZ because of precipitation from heat treatment and welding.
    Custom 455 was never designed to be welded. It's a forging stock. You*can* weld it, but its chemistry wasn't chosen to be corrosion tolerent to welding.

    XCR - 16% Cr, 5% Ni, 1% Mo. Better corrosion resistance than 953 or 410, even welded. That'll be the molybdenum. Columbus do tell you what's in it, kinda. Columbus get the tubing from Trafil, who make Werkestoffe no 1.4418 steel for it.

    Actually 304 doesn't have excellent corrosion resistance. It's normally the baseline stainless for chemical contact. Somehow, over the years that message has got a bit misinterpreted.
    "While my father fought for you, I learnt. While my father glorified your petty administration, I learnt. While he longed every day for our line, Adunís line, to be restored, I learnt. He sent me away to bring the Dark Templar back when the time was right!
    "And you tell me that I cannot do this? That I cannot feel the weight of the universe?
    "Damn you, Tellan! Aldaris killed my father!"

  14. #14
    Decrepit Member Scooper's Avatar
    Join Date
    Aug 2005
    Location
    San Francisco California
    My Bikes
    2007 Waterford 953 RS-22
    Posts
    8,613
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    ^ ^ Great! Thanks, Falanx.
    - Stan

  15. #15
    I give up! cujet's Avatar
    Join Date
    Jan 2007
    Location
    Jupiter, FL
    My Bikes
    Homemade Ti, Hab frame
    Posts
    87
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    My vote goes for Ti.

    From my simplistic point of view, Here in South Florida riding along the beach ruins just about everything. Of my many bikes, and my friends bikes, only the Ti frames last. Even then, it must be a heavy duty Ti frame, not an ultra light, super thin version. As you might expect, if built too thin, they will fail too. Unfortunatly, some Ti frames are simply too light. But they do not corrode, and if built well, they do not crack.

    I am currently at about 2000 miles on my Ti frame. My last bike, a steel frame made it about 10K miles before it was too far gone. It had corroded and cracked.

    From an aerospace point of view, Ti has been the standard for parts that need all the properties you require.



    Chris
    If it doesn't burn fossil fuel, I don't like it.

  16. #16
    eternalvoyage
    Join Date
    Feb 2007
    Posts
    2,418
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    It's possible for the search for immortality (or indestructibility, or invincibility) to find additional avenues of exploration.

  17. #17
    eternalvoyage
    Join Date
    Feb 2007
    Posts
    2,418
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by makeinu View Post
    Which frame material is the most durable?

    Folks always talk about which is lighter, which is stronger, etc, but which is the most corrosion resistant? Which is the more abrasion resistant?

    Titanium? Aluminum? Carbon? Steel?
    I've wondered about these things too, quite a bit.

    None of them will last forever.

    Some will last longer than others, and the 'winners' will be different depending on conditions.

    Even diamonds won't last forever.

    *****
    I have found it liberating to get into another mindset. It is a lot more fun, at times, to test things and see how strong they really are.

    You don't have to be in 'preservation mode' interminably. It can be a bit stultifying (or something along those lines) -- and it can be nice to wear another hat once in a while.

    *****
    [There is something oddly elusive about some of these frame materials questions and inquiries. I think we may not know exactly what it is we are after, or what we are looking for.

    Something with the aura of invincibility is nice to be around (for some reason..., at times at least).]

    *****
    [Death and mortality may be in the background of some of these inquiries and interests.]

  18. #18
    THE Materials Oracle Falanx's Avatar
    Join Date
    Feb 2006
    Location
    Finally... home :-)
    My Bikes
    Univega Alpina 5.1 that became a 5.9, that became a road bike... DMR TrailStar custom build
    Posts
    502
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by cujet View Post
    From an aerospace point of view, Ti has been the standard for parts that need all the properties you require.

    Chris
    Except in main landing gear, gearboxes, slat controls, pumps, impellers, rotors, shafts, skins, bay doors, stringers, longerons, steering knuckles, missile bodies, missile control surfaces, coolant and oil lines and three quarters of turbine assemblies, yes.

    Sorry. Aerospace engineer ;-)
    "While my father fought for you, I learnt. While my father glorified your petty administration, I learnt. While he longed every day for our line, Adunís line, to be restored, I learnt. He sent me away to bring the Dark Templar back when the time was right!
    "And you tell me that I cannot do this? That I cannot feel the weight of the universe?
    "Damn you, Tellan! Aldaris killed my father!"

  19. #19
    Senior Member
    Join Date
    Mar 2007
    Posts
    5,844
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    I'm not an engineer of any stripe, but I do have a bit of experience with bicycles. Based upon personal observation, I'd say that I've seen more broken aluminum frames than anything else, followed by carbon, steel, and titanium. And I've never seen a titanium frame rust into uselessness, either.

    Realistically, a properly cared-for steel frame should last most of a lifetime. A titanium frame will probably go at least that long, with less care. Carbon bicycle frames haven't been around long enough for us to know for sure. And aluminum frames are more susceptible to joint failure than any others, as far as I can tell, which is not to say that they can't last a very long time, but that the odds are worse than for other materials.

    HTH!

  20. #20
    eternalvoyage
    Join Date
    Feb 2007
    Posts
    2,418
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by makeinu View Post
    Which frame material is the most durable?

    Folks always talk about which is lighter, which is stronger, etc, but which is the most corrosion resistant? Which is the more abrasion resistant?

    Titanium? Aluminum? Carbon? Steel?
    I thought about this some more, and the simple and straightforward answer -- to which is the most durable (for real-world bikes, under most real-world conditions) -- is almost certainly some of the exotic steels.

    If you look at the numbers, it is striking. They are not only harder, they are much harder. The yield strengths are not only higher, they are much higher.

    They are much tougher as well, and have other superior characteristics.

    The numbers are available on the web. It can help to see them for yourself, and compare them. It brings the facts home.

    Titanium has a certain sort of name-recognition and aura and reputation; but the facts speak differently.

    953 and some of the other steels just blow it away, by these various measures.

    Some of the steels can benefit from corrosion protection, if exposed to certain conditions; but that can be arranged without too much trouble.

    *****
    That said, with a reasonable level of care, a good Ti bike can also last several lifetimes.

    So could carbon and aluminum; but they are (relatively speaking) more subject to various sorts of damage and failure.

    *****
    Scratches and abrasion resistance: the harder exotic steels win.

    *****
    If you tried using these different materials against one another in a sort of swordfight, to see which ones would destroy which, the tougher and harder exotic steels would win.

    If you threw rocks at them, carbon would probably go first, followed by aluminum.

    I've heard that titanium can develop weak spots from strong, sharp impacts; but I've never seen this confirmed.

    *****
    Corrosion resistance: it would have to depend on conditions -- just water? Heavy salt(s)? What?

    Unprotected?

    Well-protected steels will last a very, very long time -- lifetimes. Even in wet conditions. Some of the stainless steels will hold up even better.
    Last edited by Niles H.; 01-23-08 at 06:22 PM.

  21. #21
    I give up! cujet's Avatar
    Join Date
    Jan 2007
    Location
    Jupiter, FL
    My Bikes
    Homemade Ti, Hab frame
    Posts
    87
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Falanx View Post
    Except in main landing gear, gearboxes, slat controls, pumps, impellers, rotors, shafts, skins, bay doors, stringers, longerons, steering knuckles, missile bodies, missile control surfaces, coolant and oil lines and three quarters of turbine assemblies, yes.

    Sorry. Aerospace engineer ;-)
    Main landing gear of heavy jets are steel, they would be too big if made of anything else. Gearboxes contain steel gears. Slat controls may or may not contain Ti. Falcon jet slats have extensive use of Ti. Pumps are steel and aluminum. As are wear nearly all wear parts. Rotors (compressor disc and blades) are Ti on our G550, As are the impellers on the Turbomecca compressors on our heli. Also Ti are non wearing shafts in the flight control systems. Skins are Aluminum as are doors and stringers (also carbon fiber) Steering nuckles (in our case, bellcranks) are Ti on the Gulfstream. Could not say with regard to missles. Fluid lines are all stainless and turbine assys are high nickel alloy. Also, Ti is used on both our helicopter and Gulfstream firewalls.

    Quite a good mix of materials. Obviously, aerospace engineers use the proper material for the job at hand. Which really is the original question. Too bad I answered in such a simple manner.

    I think if you put the question in aerospace terms, Ti is used where long life is needed, corrosion resistance is important, thermal stability is important, weight is important, and cost is not the overriding factor. One area where Ti does not do well is any surface that has high wear or friction related issues. So the above example of gears, pumps, landing gear, and the like are clearly the realm of steel.

    But, I stand by my statement. The best bicycle frame material, IMHO is Ti. It does not need paint or corrosion protection of any type, it is strong, very resistant to fatigue failure, light, weldable, repairable, machinable, commonly available, it looks good when polished and remains polished nearly forever. It is as close to a lifetime bicycle frame material as I have ever seen. Remember that stainless does corrode. One look at any boat in salt water will prove that point.

    My Ti seat post will never get stuck in my Ti frame, ever. Nor will the bottom bracket threads corrode, ever.

    I am willing to see the error of my ways. Please let me know the down side.

    Chris
    If it doesn't burn fossil fuel, I don't like it.

  22. #22
    THE Materials Oracle Falanx's Avatar
    Join Date
    Feb 2006
    Location
    Finally... home :-)
    My Bikes
    Univega Alpina 5.1 that became a 5.9, that became a road bike... DMR TrailStar custom build
    Posts
    502
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by cujet View Post
    ...Lotsa knowledge....
    Chris
    So you are a fellow plane mech! Yay! Found one!

    Not all planes are made like the Gulfstreams or choppers though. And you'll have to excuse any confusion between our terms, being as you're one side of the pond and I'm the other. Not everything means quite the same...

    The MLG of all planes are steel. Not just the big'uns. 300M, D6AC, Hy-Tuff or Carpenter Custom 465.
    The slat control gears themselves? Or the slat stanchions/tracks/pistons?
    Compressor discs, blades, blisks and blings are usually Ti alloys these days yes, but chopper rotors aren't. And most of the jet engine parts in Ti are in development to become SiC fibre reinforced Ti-alloy composites.
    Bellcranks are Ti on the Gulfstream, too? I shall remember that ;-)
    For reference, missiles are *always* steel bodies. You can't make a thin-walled tube take a 40g hard turn at Mach 3+ if it's anything but.

    How many boat parts made of stainless steel have you seen? There aren't that many I can think of and all of those aren't really stainless steels - they're what get referred to as corrosion resistant alloys. If it doesn't contain 18% chromium, you're kidding yourself that it's stainless steel. The problem with salt water as a corrosion medium for steels is the chloride ion. While chromium-bearing steels are very resistant to oxidising media, they fair not so well in reducing media, of which the chloride ion numbers. Having said that, titanium is also attacked by Cl-. That's why proper stainless steels have over 8% nickel in them too, and preferably some nitrogen and molybdenum.

    I'll refer you to one of the framebuilders around here who makes no secret of his preference for Ti, and I can see his point. When it comes to environmental resistance per unit cost, despite the shocking rise in commodity prices, Ti still delivers most.

    It even performs just over half as well as steel in mechanical tests. If money were no object, then I can recommend only one material. I could even design it for you, right down to the heat-treatment procedure and precipitation sequence. It would be steel.

    But you'd have to be very rich.
    "While my father fought for you, I learnt. While my father glorified your petty administration, I learnt. While he longed every day for our line, Adunís line, to be restored, I learnt. He sent me away to bring the Dark Templar back when the time was right!
    "And you tell me that I cannot do this? That I cannot feel the weight of the universe?
    "Damn you, Tellan! Aldaris killed my father!"

  23. #23
    eternalvoyage
    Join Date
    Feb 2007
    Posts
    2,418
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by cujet View Post
    ... It does not need paint or corrosion protection of any type, it is strong, very resistant to fatigue failure, light, weldable, repairable, machinable, commonly available, it looks good when polished and remains polished nearly forever. It is as close to a lifetime bicycle frame material as I have ever seen. Remember that stainless does corrode. One look at any boat in salt water will prove that point.

    My Ti seat post will never get stuck in my Ti frame, ever. Nor will the bottom bracket threads corrode, ever.
    Titanium is an excellent material; but I am not at all convinced that it trumps some of the finer steels.

    Many cyclists do not have to deal with much salt at all; it varies, but many just don't have that problem to deal with, in reality.

    There are ways of protecting steel.

    Stainless steels differ widely. Some of them are much more corrosion resistant than others.

    Titanium can and does fuse with some other materials.

    Its fatigue life in some tests is unexceptional.

    *****
    "...Remember that stainless does corrode. One look at any boat in salt water will prove that point."

    This seems like one of those hypothetical examples that are not closely related to bike frames in the real world. How many bike frames sit in salt water like a boat? (What about the chain, bottom bracket, bearings, cogs, etc.?)

    If that is actually one's application, then an appropriate material for that situation is in order. Otherwise, it seems not to be very applicable. It certainly is not very applicable for many cyclists, in their actual conditions.

    There is sufficient corrosion resistance in real-world conditions, for many people, in some of the steels.

    *****
    One can imagine various sorts of situations (some of them a bit fanciful) -- and different materials will come out ahead depending on the nature of the stresses and environments.

    For most bike frames, in the real world, it seems to me that some of the steels are at least the equal of the titanium alloys.

    *****
    One could make a long list of materials' characteristics, and various possible sources of damage, and then rate each material and alloy for each set of conditions.

    (Carbon fiber would blow away the rest of the field in at least of couple of those.)

    One could then rate each one of these potential sources of damage -- rate each one for likelihood (for an individual's actual uses), duration, etc., and assign a weight to the importance of each attribute.... and tailor it to the individual and his or her needs, preferences, etc.

    For most people, it seems to me that some of the steels (especially the stainless steels) would be at least the equal of the titaniums.

    I agree that it is a close call in some ways, and that each material can look like the best, if one focuses on its strong points; but overall -- taking all of the factors into account, not focusing on just some of them, and taking actual real-world riding and real-world conditions and the individual into account -- if I could have any of the available materials in the bike of my dreams, it would probably be one of these corrosion-resistant steels.

    [Though I have to admit that the fact that scratches in brushed titanium can be easily rubbed out (as described on Habanero's site) compensates for ti's much-worse performance in that category (scratch resistance), compared with some of the hardened steels. That is a real factor for me.

    There are other factors, though, that weigh more in the steels' favor.

    It's close in some ways, though....]
    Last edited by Niles H.; 01-24-08 at 02:36 PM.

  24. #24
    eternalvoyage
    Join Date
    Feb 2007
    Posts
    2,418
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Light scratches in titanium may be fairly easy to rub out; what Habanero doesn't mention (and I don't blame them, really -- they are selling ti] is that not all scratches are of this nature, and not all of them are equally easy to deal with.

    Deeper gouges, like those mentioned here,

    Repairing the finish of a ball burnished AL frame with deep gouge?

    are not so easy.

    *****
    This makes me lean more toward the far more scratch-, abrasion-, and gouge-resistant materials that are available.

  25. #25
    THE Materials Oracle Falanx's Avatar
    Join Date
    Feb 2006
    Location
    Finally... home :-)
    My Bikes
    Univega Alpina 5.1 that became a 5.9, that became a road bike... DMR TrailStar custom build
    Posts
    502
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by Niles H. View Post
    This makes me lean more toward the far more scratch-, abrasion-, and gouge-resistant materials that are available.
    Lemme guess, they start with iron and end with a complex precipitation sequence? ;-)
    "While my father fought for you, I learnt. While my father glorified your petty administration, I learnt. While he longed every day for our line, Adunís line, to be restored, I learnt. He sent me away to bring the Dark Templar back when the time was right!
    "And you tell me that I cannot do this? That I cannot feel the weight of the universe?
    "Damn you, Tellan! Aldaris killed my father!"

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •