Explain why titanium alloy is difficult to process

The machinability of titanium alloy is 20-40% of 45# steel. If the hardness is <HB300, there will be a strong sticking phenomenon; if HB>370, it is too hard to process. The best titanium alloy with a hardness of HB300-370 is the best. The main reasons affecting its machinability are briefly described as follows: 1) Gaseous impurities (oxygen, nitrogen and hydrogen, etc.) have a great influence on the machinability of titanium alloy, because titanium is highly chemically active and easily combines with gas impurities. When the temperature exceeds 600 degrees, titanium is oxidized to form a brittle layer, the so-called "organization α layer"; it produces hydrogen embrittlement with hydrogen; and forms hard and brittle TiN with nitrogen at high temperature. 2) Titanium alloy has low plasticity, which significantly affects its plastic deformation during cutting. The deformation coefficient of titanium alloy is only 1 or even less than 1, while the deformation coefficient of ordinary carbon steel is about 3. When cutting, the chip has a very small contact surface with the front cutting edge, which makes the pressure and local temperature of the contact area high, and the tool wears quickly. 3) Severe work hardening will occur during titanium alloy processing. Grade 23 Ti-6Al-4V ELI Titanium Foil / F9 Titanium Forging / ASTM B265 Cold Rolling Titanium Sheet