The chemical activity of
titanium is large, and the atmosphere O, N, H, CO, CO2, water vapor, ammonia and other strong chemical reaction. When carbon content is more than 0.2%, cemented TiC will be formed in titanium alloy. When the temperature is high, TiN hard surface will also be formed by interaction with N. When the temperature is above 600℃, the titanium absorbs oxygen and forms a hardening layer with high hardness. When the hydrogen content goes up, the embrittlement layer also forms. The depth of the hard and brittle surface produced by the absorption of gas can reach 0.1 ~ 0.15mm, and the degree of hardening is 20% ~ 30%.The chemical affinity of titanium is also large, easy to produce adhesion with the friction surface.
The thermal conductivity of small titanium = 15.24w/(m.K) is about 1/4 that of nickel, 1/5 that of iron, and 1/14 that of aluminum, while the thermal conductivity of various titanium alloys is about 50% lower than that of titanium. The elastic modulus of titanium alloy is about 1/2 of steel, so its rigidity is poor, easy to deformation, it is not suitable to make slender rod and thin wall parts, cutting processing surface springback is very large, about 2 ~ 3 times of stainless steel, resulting in severe friction, adhesion, adhesive wear tool after the tool.
Therefore, according to the metal characteristics of titanium alloy above, we can know that titanium is a kind of metal with high strength, high hardness, high thermal conductivity and low thermal conductivity. So wire cutting is through the phenomenon of electrical corrosion, molybdenum wire and workpiece through high-frequency discharge, instantaneous high temperature melting metal cutting. The high thermal property and low thermal conductivity of hot titanium can easily cause the local burning phenomenon when we process titanium.
And the high strength of the metal, wire cutting processing feed speed must not be too fast, easy to cause a short circuit.
