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First, the characteristics of titanium and titanium alloy

Titanium and titanium alloy has many excellent features, mainly reflected in the following aspects:
1, high strength. Titanium alloy having a high strength, a tensile strength of 686-1176MPa, while the density is only about 60% of the steel, so than the high intensity.
2, high hardness. The titanium alloy (annealed) Hardness HRC 32-38.
3, the low modulus of elasticity. The elastic modulus of the titanium alloy (annealed) as half of 1.078 × 10-1.176 × 10MPa, approximately steel and stainless steel.
4, the high temperature and low temperature performance is excellent. At high temperatures, the titanium alloy can still maintain good mechanical properties, the heat resistance is far higher than that of aluminum, and a wide operating temperature range, the working temperature of the new heat-resistant titanium alloy up to 550-600 ° C; at low temperatures titanium strength rather than at room temperature increased, and has good toughness, low temperature titanium alloy can also maintain good toughness at -253 ℃.
5, titanium corrosion resistance. Titanium in the air of 550 ° C or less, the surface will quickly form a thin, dense titanium oxide film, the corrosion resistance is superior to most stainless steels, and therefore in the oxidizing medium to the atmosphere, water, nitric acid and sulfuric acid, etc. and alkali.

Titanium and titanium alloy processing performance
1, the cutting performance
Titanium alloy, high strength, hardness, so the power processing equipment, molds, cutting tools should have high strength and hardness requirements. Machining the contact area of ​​the chip and the rake face stress tool tip. Compared with 45 steel, titanium alloy cutting force only 2/3-3/4, but the contact area of ​​the chip and the rake face are much smaller (only 45 steel 1/2-2/3), so the tool the stress of the cutting edge but more, the tool tip or the cutting edge is easy to wear; titanium large friction coefficient, while the contact of the tool and chip of the low thermal conductivity (respectively, only 1/4 and 1/16 of the iron and aluminum); high cutting temperature, resulting in a short length, the the cutting heat build-up in the vicinity of the cutting edge of the small area within easy distribution, these factors make titanium alloy the tool wear expedite affect the processing quality. Because titanium low modulus of elasticity, when machining the workpiece springback, likely to cause the tool flank wear intensifies and the deformation of the workpiece; titanium high chemical activity at high temperature easily occur with the hydrogen in the air, oxygen and other gaseous impurities chemical reaction to produce a hardened layer, while further exacerbated by the tool wear; titanium alloy machining, the workpiece material can easily bond surfaces and the tool, plus the high cutting temperature, so that the tool is easy to produce diffusion wear and adhesive wear.
2, grinding performance
The lively nature of titanium alloys under high temperature and abrasive affinity and adhesion, blockage grinding wheel, resulting in increased wheel wear, grinding performance degradation, grinding easy to ensure accuracy. Wheel wear also increases the area of ​​contact between the grinding wheel and the workpiece, resulting in deterioration of the cooling conditions, the grinding zone temperature rise sharply, the greater thermal stress is formed in the grinding surface layer, caused by partial burn of the workpiece, resulting in grinding cracks. Titanium alloy, high strength, toughness, so that the debris is not easy separation grinding, grinding force increases, grinding a corresponding increase in power consumption. Titanium alloy with low thermal conductivity, specific heat, thermal conductivity grinding slow, resulting in the accumulation of heat in the grinding arc, resulting in a sharp increase in the grinding zone temperature.
3,Extrusion performance
Extrusion machining of titanium and titanium alloys, it is required that the high extrusion temperature, extrusion speed, to prevent temperature drop too fast, and should try to shorten the contact time of the high \ temperature ingot mold. Extrusion die mold material should be used in the new heat billets from the furnace to the conveying speed extrusion cylinder should fast. In view of the metal susceptible to gas pollution in the heating and extrusion process, it should also adopt appropriate protective measures. Extrusion should choose the right lubricant, to prevent bonding mold, such as extrusion sheath extrusion and glass lubricating. Extrusion deformation due to large deformation of titanium and titanium alloy thermal effects, poor thermal conductivity, but also pay special attention to prevent overheating. The extrusion process than the titanium alloy, aluminum alloy, copper alloy, and even the extrusion process of the steel is more complex, which is determined by the special physical and chemical properties of a titanium alloy. Titanium alloy in the conventional thermal anti-extrusion, the mold temperature is low, the dough in contact with the mold surface temperature decreased rapidly, and the dough within the deformable heat and the temperature rise. Titanium alloy with low thermal conductivity, surface temperature drops, the inner blank heat can not be transferred to the surface supplement, there will be surface hardened layer, and the deformation is difficult to proceed. Meanwhile, the surface layer and the inner layer will produce a large temperature gradient, and even can be formed, but also is likely to cause deformation and uneven. 4, forging processing performance 
Titanium alloy forging process parameters is very sensitive, forging temperature, the amount of deformation, deformation and cooling rate of change will cause changes in the titanium alloy microstructure and properties. In order to better control of the microstructure and properties of the forgings, in recent years, the hot-die forging, etc. isothermal forging advanced forging technology has been widely used in the production of forged titanium.

Titanium alloy of the plastic increases with increasing temperature in the temperature range of 1000-1200 ℃ plastic reaches its maximum, allowing the degree of deformation of up to 70% -80%. Titanium alloy forging temperature range is narrow, should be strictly in accordance with the (α + β) / β transition temperature to master (ingot blooming excluded), otherwise the β grain severe grew up, reducing the room temperature ductility; (α α titanium alloy usually + β) two-phase region, forging, β (α + β) / β phase transition line above forging temperature is too high, and will lead to brittle phase beta titanium alloy whose initial forging and final forging must be higher than the (α + β) / β transformation temperature. The case of the deformation resistance of the titanium alloy is increased rapidly with increasing deformation speed forging temperature greater deformation resistance of titanium alloy, the conventional forging must be cooled within a forging die least completed. The content of interstitial elements (such as O, N, C) of a titanium alloy forging also has a significant impact.