Hi Walter, so if I send you an axle from my MX bike (a really basic axle) it can be made in Titanium for about $75.00, that is good value.
I am interested in the comment you make about Titanium, I had a look in the 2012 MA rulebook and could only see "not allowed" for frames axles etc for Roadracing or Speedway, but no mention of MX, I wonder why.
As to "Titanium changing its structure during use and therefore has limited time of use before it can break", I'm not too sure about that, the following is the Wiki entry on the stuff and it looks pretty good:
Titanium alloys are metallic materials which contain a mixture of titanium and other chemical elements. Such alloys have very high tensile strength and toughness (even at extreme temperatures), light weight, extraordinary corrosion resistance, and ability to withstand extreme temperatures. However, the high cost of both raw materials and processing limit their use to military applications, aircraft, spacecraft, medical devices, connecting rods on expensive sports cars and some premium sports equipment and consumer electronics. Auto manufacturers Porsche and Ferrari also use titanium alloys in engine components due to its durable properties in these high stress engine environments.
Grade 5, also known as Ti6Al4V, Ti-6Al-4V or Ti 6-4, is the most commonly used alloy. It has a chemical composition of 6% aluminium, 4% vanadium, 0.25% (maximum) iron, 0.2% (maximum) oxygen, and the remainder titanium. It is significantly stronger than commercially pure titanium while having the same stiffness and thermal properties (excluding thermal conductivity, which is about 60% lower in Grade 5 Ti than in CP Ti). Among its many advantages, it is heat treatable. This grade is an excellent combination of strength, corrosion resistance, weld and fabricability. Consequently, it is used extensively in Aerospace, Medical, Marine, and Chemical Processing E.g.internal combustion engine connecting rods and surgical implants. Generally, it is used in applications up to 400 degrees Celsius.
It has a density of roughly 4420 kg/m3, Young's modulus of 110 GPa, and tensile strength of 1000 MPa. By comparison, annealed type 316 stainless steel has a density of 8000 kg/m3, modulus of 193 GPa, and tensile strength of only 570 MPa. And tempered 6061 aluminium alloy has 2700 kg/m3, 69 GPa, and 310 MPa, respectively.
Grade 6 contains 5% aluminium and 2.5% tin. It is also known as Ti-5Al-2.5Sn. This alloy is used in airframes and jet engines due to its good weldability, stability and strength at elevated temperatures.
And from Azom.com
In the automotive industry, uses are being developed for titanium in the automotive/motorcycle after markets and racing market. Engine parts such as connecting rods, wrist pins, valves, valve retainers and springs, rocker arms and camshafts, to name a few, lend themselves to fabrication from titanium, because it is durable, strong, lightweight and resists heat and corrosion. While titanium initially may be more expensive for these applications, designs that exploit its unique characteristics yield parts that more than pay for themselves with better performance and a longer life.
If there are any Engineers out there with some constructive or critical comment feel free to chime in, it is something that interests me, because if Walter can save me 50% from the weight of my axles for $75 that's a much better deal than Jenny Craig would offer me for my gut removal