The reasons for the difficulty in processing titanium alloys are as follows:

 

Gas impurities (oxygen, nitrogen, hydrogen, etc.) have a great influence on the machinability of titanium alloys, because titanium has high chemical reactivity and is easily combined with gas impurities. When the temperature exceeds 600 degrees, titanium is oxidized to form an embrittlement layer, a so-called "tissue gelatinization layer"; hydrogen brittleness is generated with hydrogen; and hard and brittle TiN is formed with nitrogen at a high temperature.

 

The plasticity of titanium alloy is small, which obviously affects the 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 rake face, which makes the contact zone pressure and local temperature high, and the tool wears fast.

 

Titanium alloys can cause severe work hardening during processing.

 

When C>0.2%, the titanium alloy forms a hard carbide, which causes abrasive wear of the tool and reduces machinability.

 

Expanding information:

 

Titanium is an important structural metal developed in the 1950s. Titanium alloy has high strength, good corrosion resistance and high heat resistance. In the 1950s and 1960s, it was mainly the development of high-temperature titanium alloys for aircraft engines and structural titanium alloys for the body.

 

In the 1970s, a number of corrosion-resistant titanium alloys were developed. Since the 1980s, corrosion-resistant titanium alloys and high-strength titanium alloys have been further developed. Titanium alloys are mainly used to make aircraft engine compressor components, followed by structural components for rockets, missiles and high-speed aircraft.