Why is titanium alloy difficult to process

The machinability of titanium alloy is 20-40% of that of 45# steel, and if the hardness is less than HB300, strong knife sticking will occur; if HB>370, it is too hard to process, so it is best to process titanium alloys with a hardness of HB300-370. The main reasons affecting its machinability are briefly described as follows: 1) Gas impurities (oxygen, nitrogen and hydrogen, etc.) have a great influence on the machinability of titanium alloys, because titanium has high chemical activity and is easy to combine with gas impurities . When the temperature exceeds 600 degrees, titanium welding filler wire is oxidized to form an embrittlement layer, the so-called "tissue alpha layer"; hydrogen embrittlement occurs with hydrogen; hard and brittle TiN is formed with nitrogen at high temperature. 2) The plasticity of titanium alloy is small, which obviously affects its plastic deformation during cutting. The deformation coefficient of titanium alloy is only 1 or even less than 1, while that of ordinary carbon steel is about 3. When cutting, there is a very small contact surface between the chip and the rake face, so that the pressure and local temperature in the contact area are high, and the tool wears quickly. 3) Severe work hardening will occur when titanium alloy is processed. 4) When C>0.2%, the Grade 3 Pure Titanium Tube alloy will form hard carbides, which will cause abrasive wear of the tool and reduce the machinability