Originally Posted by
Falanx
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