Titanium alloy with high strength and density, good mechanical properties, toughness and good corrosion resistance. Further, the titanium alloy of the process performance is poor, cutting is difficult, very easy to absorb impurities such as nitrogen and carbon hydroxide During thermal processing. There are poor abrasion resistance, the complexity of the production process. Titanium industrial production began in 1948. Needs of the development of the aviation industry, the titanium industry with an average annual growth rate of approximately 8%. World titanium alloy material production reached 40,000 tons, nearly 30 kinds of titanium alloys. The most widely used titanium alloy Ti-6Al-4V (TC4), Ti-5Al-2.5Sn (TA7) and commercially pure titanium (TA1, TA2 and TA3). Titanium alloy is mainly used for the production of aircraft engine compressor components, followed by rockets, missiles and high-speed aircraft structural parts. The mid-1960s, titanium and its alloys in general industrial applications, for the production of the electrodes of the electrolysis industry, power station condensers, heater petroleum refining and desalination, as well as environmental pollution control device. Titanium and its alloys have a corrosion resistant structural material. In addition, for the production of a hydrogen storage material and shape memory alloy. China began in 1956, titanium and titanium alloys; industrial production and the development of TB2 alloy titanium the mid-1960s. Titanium alloys used in the aerospace industry an important new structural materials, specific gravity, strength and temperature range between aluminum and steel, but has a high specific strength and excellent resistance to seawater corrosion and ultra-low temperature performance. In 1950, the United States for the first time used on the F-84 fighter-bombers as body insulation panels, wind guide cover, tail cover non-bearing components. The use of titanium alloy parts in the mid-1960s toward the fuselage from the rear fuselage, in part, instead of structural steel bulkheads, beams, flap track bearing components. The quantity of titanium alloy in the aircraft rapidly increase, reaching 20% ??to 25% of the weight of the aircraft structure. 1970s, civilian aircraft began extensive use of titanium alloys, such as the Boeing 747 with titanium capacity of more than 3640 kg. Aircraft Mach number is less than 2.5 is to replace steel in order to reduce the structural weight of titanium. Another example, the SR-71 high-altitude high-speed machine (flight Mach 3 at an altitude of 26,212 meters), titanium accounted for 93% of the weight of the structure of the aircraft, known as "titanium" aircraft. When aviation engine thrust-to-weight ratio increased from 4 to 6 to 8 to 10, the compressor outlet temperature increased from 200 to 300 ° C to 500 to 600 ° C, the original low pressure compressor disks and blades made of aluminum must switch to titanium or titanium instead of stainless steel high-pressure compressor disks and blades, in order to reduce the structural weight. In the 1970s, the amount of titanium alloys in aircraft engines usually accounts for 20% to 30% of the total weight of the structure, is mainly used for the manufacture of compressor components, such as the forging of titanium fan, compressor disks and blades, cast titanium compressor casing, intermediary casing and bearing housing. Spacecraft titanium high specific strength, corrosion resistance and low temperature performance to produce a variety of pressure vessels, fuel tanks, fasteners, instruments and bandages, architecture and rocket casing. Artificial earth satellites, lunar module, manned spacecraft and space shuttle are also using titanium alloy sheet welding parts. High thermal strength, able to maintain the required strength at moderate temperatures, can be at a temperature of 450 to 500 ° C. The long-term work, several hundred degrees higher than the temperature of the aluminum alloy of these two types of titanium is still within the range of from 150 ° C to 500 ° C The high strength-to-weight ratio, while the aluminum alloy in the 150 ° C when the ratio of the intensity decreased. The titanium working temperature up to 500 ° C, aluminum alloy below 200 ℃. Corrosion resistance of titanium alloys in a humid atmosphere and seawater, the corrosion resistance far superior to stainless steel; pitting, etching, stress corrosion resistance particularly strong; alkali, chloride, chlorine organic items , *, sulfuric acid has excellent corrosion resistance. However, titanium the differential resist having a reduced oxygen and chromium salts medium. In the low and ultra-low temperature, low temperature performance titanium can still maintain its mechanical properties. Good low temperature performance, low interstitial elements titanium, TA7, at -253 ℃ can maintain a certain plasticity. Therefore, titanium is also an important low-temperature structural material. The chemical activity of large chemical activity of the titanium to produce a strong chemical reaction with the atmosphere in O, N, H, CO, CO2, water vapor, ammonia, etc.. Carbon content greater than 0.2%, it will form a hard TiC in titanium; temperature is high, and the N role will form a hard surface of the TiN titanium alloy products; above 600 ℃, titanium absorbs oxygen to form high hardness hardened layer; increase in hydrogen content, and also the formation of brittle layer. Hard and brittle surface layer depth of up to 0.1 to 0.15 mm to absorb the gas generated from 20% to 30% of the degree of hardening. The chemical affinity of titanium is also easy with the friction surface adhesion phenomenon. Small thermal conductivity, the elastic modulus is small titanium coefficient of thermal conductivity λ = 15.24W / (mK) is approximately 1/4 of the nickel, iron, 1/5, 1/14 of the aluminum, while the thermal conductivity of various titanium to titanium the thermal conductivity of a decrease of approximately 50%. Titanium elastic modulus of about 1/2 of the steel, so the difference in rigidity, easy to deform, not the production of elongate rods and thin-walled parts, the machined surface when cutting a large amount of springback, stainless approximately 2 to 3 times, resulting in the tool flank intense friction, adhesion, adhesive wear.