Cutting processing of titanium alloys

Due to the presence of various alloy elements in titanium alloys, including some elements with high activation energy, they exist in a relatively stable state within the alloy. Therefore, titanium alloys have significant energy in terms of plastic deformation and possess certain machinability. However, titanium alloys have poor thermal conductivity. During cutting processing, the cutting heat accumulates on the cutting tool, unlike the cutting process of aluminum, where the cutting heat is carried away by the chips. This results in a large thermal load on the titanium alloy material and damage to the cutting tool. Therefore, the common method of increasing production efficiency by increasing the removal amount within a certain time range is not applicable to the processing of titanium alloy materials. Thus, appropriate processing methods should be selected for different titanium alloy materials.

(1) Titanium alloys have high strength, great toughness, and high hardness, so the problem of hardening is relatively serious during cutting processing. This requires annealing treatment. Especially when the workpiece surface has scratches or cuts, since they are very sensitive to the deformation speed, during the cutting process, they are prone to produce scratches or cracks, so the processing speed must be controlled at a low speed.

(2) Generally, titanium alloys have good thermal stability and high temperature resistance. Compared with aluminum alloys, the strength of titanium alloys is much higher. During cutting processing, the thermal conductivity of titanium alloys is very low, equivalent to a small part of iron and aluminum materials. Its heat is concentrated on the cutting edge. When the temperature exceeds a certain standard, it will become highly chemically active and react with oxygen and hydrogen in the air, thereby reducing its plasticity. When in contact with the tool surface and chips, it will intensify the wear on the tool.

(3) During cutting processing, due to the certain friction between titanium alloys and the cutting tool, as the friction speed increases, the temperature will rise, the power will increase, the tool wear will accelerate, and it is prone to adhesion, thus significantly shortening the tool's service life. Therefore, the rational selection of cutting tools is also very crucial. Usually, some hard alloy materials such as tungsten-cobalt hard alloys are selected. This can effectively prevent the generation of adverse stresses during the processing and ensure the machining accuracy of the components.

The characteristics of titanium alloys exhibited during cutting processing make the cutting processing of titanium alloys very difficult, resulting in reduced production efficiency and increased production costs. Therefore, in the titanium alloy cutting processing technology, processing schemes need to be continuously improved, and reasonable processing process parameters should be adjusted to improve the processing quality of titanium alloys.