Why titanium alloy is a difficult-to-machine material?

Why do we think that titanium alloy is a difficult-to-machine material? Because of the lack of deep understanding of its processing mechanism and phenomenon. 1． Physical performance at titanium processing The cutting force of titanium alloy is only slightly higher than that of steel with the same hardness, but the physical performance of machining titanium alloy is much more complex than that of machining steel, which makes the machining of titanium alloy face enormous difficulties. The thermal conductivity of most titanium alloys is very low, only 1/7 of that of steel and 1/16 of that of aluminum. Therefore, the heat generated in the process of cutting titanium alloy will not be quickly transferred to the workpiece or taken away by the chips, but will be gathered in the cutting area, and the temperature generated can be as high as more than 1 000 ℃, so that the cutting edge of the tool is rapidly worn, cracked, and built-up edge is generated, and the rapidly worn cutting edge generates more heat in the cutting area, which further shortens the life of the tool. The high temperature generated in the cutting process also destroys the surface integrity of titanium alloy parts, resulting in the decline of geometric accuracy of parts and the appearance of work hardening which seriously reduces their fatigue strength. The elasticity of titanium alloys may be beneficial to the performance of parts, but in the cutting process, the elastic deformation of the workpiece is an important cause of vibration. The cutting pressure causes the “elastic” workpiece to move away from the tool and rebound, so that the friction between the tool and the workpiece is greater than the cutting action. The friction process also generates heat, which aggravates the problem of poor thermal conductivity of titanium alloys. This problem…