Titanium vs. steel

Discussion in 'General Science & Technology' started by Facial, Mar 17, 2006.

?

Your favorite of the two?

  1. TITANIUM

    35 vote(s)
    71.4%
  2. STEEL

    14 vote(s)
    28.6%
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  1. Diode-Man Awesome User Title Registered Senior Member

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    1,372
    I would at least think the titanium could be placed for the long underground water-ways.

    This could be solved with having a steel end and outter wall, but a titanium inner coated shaft. (for the pipes that go from main supply to house) This would majorly reduce the intake of corroded metals into drinking water. I live in a house that was built in 1967 and already the water tastes of metal. Once we went on vacation and returned after about 2 weeks of no use and the water was rust colored until after a good rushing out period.
     
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  3. phlogistician Banned Banned

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    10,342

    Ah, you have steel pipes. Not good. Copper is an anti-bacterial and helps stop e-coli etc breeding in systems, that's a definite bonus.
     
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  5. jargon Registered Member

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    22
    titanium is way slicker lookin when you're sporting it on your ring finger like a champ - you know in order to be a ballah you have to have a ring on the fingah
     
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  7. danneva Registered Member

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    There are many metals used for making jewelry. Two popular alternatives from the ordinary are stainless steel and titanium. Both are durable metals, are more affordable than platinum and gold and make a great option for a more modern piece of jewelry. However, there are differences between stainless steel and titanium than will affect your purchase decision. Both metals will never discolor, tarnish or corrode. They also can easily withstand moisture. Both are hypoallergenic and will never cause a reaction on the skin. Both are durable metals that can withstand wear and tear of everyday use and require little maintenance. But titanium cannot be sized because it cannot be soldered. Titanium is very difficult to work with and can wear down jeweler’s tools quickly.
     
  8. dhcracker Registered Senior Member

    Messages:
    196
    Actually steel is far stronger than titanium. Titanium is just light and strong, steel is heavier but the same volume of steel vs titanium the steel (good grade of course) will have a much higher tensile strength.

    I work steel, its cheap, its strong, so far as building something that weight isn't an issue.

    Some aircraft steels are extremely strong, I've seen tensile strengths over 160,000 psi!

    Titanium has a big hype because its used in spacecraft, actually its used because its lightweight not because its stronger than steel.. its light and strong enough for most things. Also it handles heat well and temperature changes, its pretty cool in its own right I'm just partial to the material I use the most I guess.
     
  9. dhcracker Registered Senior Member

    Messages:
    196
    If you want to make a ring or something out of titanium, don't go to a jeweler go to a machine shop. I never thought of selling titanium jewelery lol...

    Also I like working white copper, its really shiny its like stainless steel without any steel.. copper/nickel/ zinc or some other alloy. White copper is shiney lusters well and is very ductile, its also called german silver and has been used in the past for jewelery. Sometimes you find white copper in old army electronics and such as well.
     
  10. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    23,198
    Yes but it is very hard to work with (Special atmospheres to weld etc. that linited the size the US could work).

    A little more than 50 years ago I had special, water cooled, probe made of it at LASL, one of the few places in the US that could work even small pieces of it back then.

    Yet then USSR was already making the leading edges of it super sonic fighter jets with it as nothing else would keep its strength at those temperatures.

    I think this is why the MIGs were significantly faster than anything the US had in the Korean war. Fortunately, for the US the USSR put its money into technology and not much into pilot training, so in a dog fight we killed many for every US loss, but often they would turn tail and run for the boarder with China and all the US could do was say: By-By, Hope you stay and fight next time.
     
  11. Facial Valued Senior Member

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    2,217
    I haven't seen this thread in a long time.

    What I can say is that the maximum strength - to - weight ratios for the strongest steels and titanium are very close, with titanium being slightly superior.

    The high-temperature strength for titanium is also usually superior to steel because of the crystal structure, which is normally hexagonal close-packed at room temperature. For steel it is body-centered cubic but changes to a much weaker face-centered cubic form at elevated temperatures.

    At room temperature, the absolute hardness (scratch/indentation resistance) for hard steels is greater than most titanium, with the exception of beta titanium which is comparable with high-carbon steel. The hardness to weight ratio for beta titanium is much greater than for the hardest tool (M6, 440C) steels. Rockwell C hardness for beta Ti and 440C stand at around 58 and 60, respectively.
     
  12. Facial Valued Senior Member

    Messages:
    2,217
    Note that there are some steels developed recently (as in, within the past few decades)for high-temperature applications, such as 17-7PH stainless.
     
  13. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    23,198
    That is correct and few know that. Why do you?

    Do you also know that this is Phase Change? With a latent heat, just like ice going to water at a constant temperature taking 80 calories / gm? I.e. if heat is supplied at constant rate the temperature will rise steadily and then stop rising until the change to face-centered cubic phase is complete before resuming the temperature rise. If I once knew the calories /gm required, I have long ago forgotten it. I think, and seem to remember, that there is a slight expansion. I.e. the face centered phase is slightly less dense. Is that correct?

    Reason I think the FCC is less dense than the BCC is that in the BCC the central atom was not shared with any other unit cube and slight further from the 4 corner atoms nearest to it, which are each shared with three other unit cubes. When in the FCC phase that formerly unshared central atom is shared with one other unit cube and closer now to their 4 corner atoms - forcing them to be slightly further apart. I.e. the unit cube becomes slightly larger so in the FCC phase, iron is slightly less dense.
     
    Last edited by a moderator: Oct 23, 2010
  14. dhcracker Registered Senior Member

    Messages:
    196
    Yeah, the newer steels are superior in all but where you need lightweight applications. If you just need brute strength steel is by far the stronger.. strength to weight is a decieving statistic steel is MUCH stronger.


    SAE Grade 8 (AS 2465 High Tensile Steel) 150,000 foot pounds tensile strength

    Commercial (99.2% pure) grades of titanium have ultimate tensile strength of about 63,000 psi (434 MPa), equal to that of common, low-grade steel alloys.

    Now..some titanium alloys do achieve a tensile strength of over 200,000 psi or 1400 mpa (a little higher than the above steel) however above 800 degree f it loses that strength drastically.

    However some modern maraging steels now have tensile strengths of over 300,000psi.

    However my favorite steel, the steel that takes the cake because its low cost and you can literally build supersonic aircraft out of it.. englin steel.

    Englin steel, just plain old es-1 at room temp has a tensil strength of about 225,000 psi, a breaking point or yield point around 264,000 psi, rockwell hardness is 45.6, and the charpy notch impact is sitting pretty at around 56 foot pounds. And heat doesn't weaken it that much! The stuff is a perfect balance of cost, strength, high temperature strength, and hardness. Its the best material for projects requiring a good all around performance metal. I swear by the stuff.

    And btw if you take plain old cheap es-1 grade and you water quench it properly... you now have es-5 grade and that stuff is no joke. Es-5 yield strength is around 245,000 psi and ultimate yield is 292,000 psi.

    Englin Steel kicks titaniums arse if you ask me, titanium may dissipate heat really well but once you get that stuff hot its useless it loses all strength.

    Further if you temper the stuff a little
     
  15. krazedkat IQ of "Highly Gifted"-"Genius" Registered Senior Member

    Messages:
    262
    Steel, it's much easier to produce and gets the job done.
     
  16. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    I am nearly sure that this is wrong when the temperate is hotter but do not remember at what temperature your quenched steel will start to anneal. Also I do not remember what temperature the BCC converts to FCC steel, but surely then and above titanium kicks steel's arse.

    Also "dissipate" is the wrong term. - That refers more to the ability to conduct (or radiate) away heat, and I think steel is better than titanium at least in heat conduction (and possibly "blacker" in the IR too). In both cases however, this will change with the crystalline structure and the presence of lattice defects, especially including the impurities.
     
    Last edited by a moderator: Oct 23, 2010
  17. dhcracker Registered Senior Member

    Messages:
    196
    Actually if you look at titaniums chemical properties.... maybe I said it wrong but its easy to get steel hot. If I'm cutting a piece of 3 ft rebar thats say 3 inches thick it will be noticably much warmer at the far end. Titanium is very hard to get hot but once it is hot its strength is less than that of a good quality tempered steel. I have worked both metals and I have took es-1 and turned it into es-5 by water and air quenching, then I subjected a strip of it to test. I own a machine shop and I often build crazy projects

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    too much free time I guess lol.

    Anyway you can verify that I'm certain of it.
     
  18. quantumdarkness19 Registered Member

    Messages:
    30
    Steel can't carry titanium's jock!!! GO TITANIUM!!! LOL
     
  19. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    23,198
    At room temperature it can and do so much more cheaply. What you crudely say is true at higher temperatures because at temperature of leading edges of super-sonic jets etc. steel has lost much of its strength. As illustrated in graph below:

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    This graph is of tensile strength as a function of temperature in degrees Celsius (C).

    I was initially surprised that there is no inflection point at temperature of the BCC /FCC phase change, but then I realized that almost all of the "pinning" against unit cell slip is due to the interstitial impurity atoms like carbon and nitrogen atoms present in the steel. (Quite a lot of Nitrogen, as atoms I think, dissolves in steel from the air.)

    To make these C temperatures more easily understood here is a "color table" for metal radiators. (First column is temperature in Centigrade second is Farenheit):

    400 752 Red heat, visible in the dark
    474 885 Red heat, visible in the twilight
    525 975 Red heat, visible in the daylight
    581 1077 Red heat, visible in the sunlight
    700 1292 Dark red ------------------ Here steel has less than 20% of its Room Temperature strength*
    800 1472 Dull cherry-red
    900 1652 Cherry-red
    1000 1832 Bright cherry-red
    1100 2012 Orange-red

    --------------
    *Why I can bend a six foot long, inch diameter, steel rod with my gloved hands as it starts to glow at the mid point.
     
    Last edited by a moderator: Oct 30, 2010
  20. dhcracker Registered Senior Member

    Messages:
    196
    Ok guys lets not get confused, Titanium doesn't get hot easy at all. HOwever its VERY WEAK when it does get hot. However supersonic forces cannot make it reach a critical temp, where steel can conduct heat VERY GOOD titanium does not. I have a piece in the shop I often put a blow torch on one end and get it hot, then I ask someone to grab the other end and yet its still quiet cool.

    So as far as what is stronger at higher temperature of the metal itself not the environment.. steel is stronger. HOwever Titanium resists the heat very very well, so though you have it in an very hot environment it will not get hot.

    But then again alloys of titanium do take heat well, but if we are talking pure titanium then...

    From wiki's titanium article check it out its pretty cool article. I would wonder how a titanium/steel alloy performs.
     
  21. Facial Valued Senior Member

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    2,217
    It was part of my engineering curriculum from long ago (6 years?). It is a phase change indeed, although one that is not visually apparent. The BCC phases are actually less dense than the FCC (the atomic packing factor, which measures the geometric density, is 0.68 for BCC, and 0.74 for FCC)

    In BCC, the corner "eighth" atoms are shared by 7 other unit cubes, since any one of them is located on the apex of the cube.

    The second assertion - that FCC causes the dimensions of the cube to be larger for the same atomic diameter - is correct. However, the arrangement of atoms is also different in such a way to compensate for this and still end up with a denser material. One way (other than the atomic packing factor) is to consider the coordination number - how many neighbors touch. For FCC it's 12, and for BCC it's 8.

    This is interesting because in the case for steel, I didn't know about the latent heat thing. People probably overlook it since it is heated at such high temperatures, and that the mechanical deficiency which results is of no interest. I think it's fascinating because you can possibly try to engineer metastable states like they do with partially stabilized ceramics (pinching cracks shut from a pressure-relieved phase change).
     
  22. Facial Valued Senior Member

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    2,217
    Yeah, this is one of my favs. I've never seen or touched it, but apparently it's taken notice outside the military in the bicycle industry. Reynolds 953 is built from maraging steel.

    Prestressing tendons, used for prestressed concrete, achieve strengths of over 200 ksi. Their composition is a high-carbon, strain-hardened, x-alloy (I really don't know the minor alloy elements) steel.
     
  23. Facial Valued Senior Member

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    2,217
    I was more curious as to how an aluminum-steel alloy performs. They have made these, specifically for experimental high-temperature applications.

    The problem I'm guessing is that you have different crystal phases, titanium being HCP, aluminum being FCC, and iron being BCC (all at room temperature) and that they do not dissolve well within one another. However, I can see why they do the aluminum-iron alloys, since both are FCC and therefore soluble at elevated temperatures. It would be interesting to see what forms result from a rapid cooling - metallic glass? Metastable metals?
     
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