The extraction of titanium
Nowadays, the commonly used extraction method is the reduction method of titanium tetrachloride. Compared to copper and zinc, although high in content, much more expensive. On the other hand, China is the country with the largest reserves of titanium, and a large number of steel mills with perennial overcapacity began to produce titanium, so the price of titanium fell year after year.
About industrial pure titanium
For the industrial pure titanium, titanium content is not less than 98%, containing a small amount of oxygen, nitrogen, hydrogen, carbon, silicon, and iron impurities such as dense metal. The labels are TA1,TA2,TA3,TA4. It's arranged by more and more impurities. The TA1 titanium content is more than 99.5%, and the price is not high. But no matter which links, for molding, welding, polishing, processing difficulty is very great.The price of almost all titanium alloys in the national standard is higher than that of pure titanium.
In reality, the price of β titanium is higher than pure titanium. Pure titanium is almost no elastic, but β titanium is not only elastic, and has the advantages of ultra-light corrosion resistance. β titanium does not have a specific composition. Memory titanium can cost tens or even tens of times as much as pure titanium.
Using memory alloy to make glasses frame is the use of its superelastic characteristics at a certain temperature (elasticity is several times that of stainless steel) and did not use its memory function. Compared to beta-titanium, memory titanium is so difficult to process. It is so elastic that shaping is difficult and impossible at room temperature, and memory titanium heat treatment is another difficult and even secret process.
Titanium is difficult to process.
Titanium is difficult to machine. Pure titanium is very soft and usually not suitable for use as titanium products, so other elements need to be rejoined. For example, ti-64, which is commonly used in the aviation industry, has to be mixed with many other elements to improve the performance of the metal.
Titanium frame machining is complicated.
The elastic modulus of titanium alloy is small, which is easy to produce large deformation, springback, distortion, and vibration in cutting, resulting in poor geometric shape and accuracy of the workpiece. As the surface roughness increases, the tool wear increases. The thermal conductivity of titanium alloy is poor and its thermal conductivity is small, 1/6 of that of 45 steel, so the high heat generated in processing cannot be effectively diffused. It is even harder to use titanium to make glasses. The frames are very thin and a lot of fine work is demanded. It's definitely a challenge for titanium, which is pretty difficult to work with. In addition, titanium alloy frames involve titanium alloy welding technology, which is more difficult.