Application of titanium and its alloys Aerospace titanium castings

Because of the dense titanium light weight, high strength than aluminum, can be maintained at a high temperature Aerospace titanium castings than aluminum and high-strength aerospace industry are highly valued. Given the density of 57% of titanium steel, Its (strength / weight ratio or strength / density ratio of them registering intensity) than high strength, corrosion resistance, anti-oxidation, anti-fatigue capabilities are strong, 3/4 titanium alloys used in aerospace structures for the generation of alloys Structural materials table, 1/4 is mainly used as corrosion resistant alloys. Titanium has a low strength and high plasticity, medium and high strength of the strong points for the 200 (low intensity) to 1300 (high strength) MPa, but in general can be seen as a high-strength titanium alloy. They are considered to be more than Strong strength aluminum alloy for high strength titanium precision casting has been completely on some models can replace steel. And the strength of the aluminum alloy at a temperature above 150 ℃ decreased rapidly compared certain titanium Gold at 600 ℃ still maintain good strength. In addition to strength, according to purpose can be divided into heat and corrosion resistance, low temperature and special features (such as TiNi shape memory alloy, TiFe hydrogen storage alloys) and other alloys, the phase composition can be divided by α, α + β and β and near-α, and several types of metastable. Alloy production so far has more than 100 species, only about 10 species widely used in industry. Which make the structure of Ti alloy -6Al-4V titanium alloy accounted for in the whole sale market of 60%, ranking the leading position, followed by Ti-5Al-2.5Sn, its long-term working temperature up to 500 ℃ (780 ~ 980 MPa strength) . However, there are two major factors that make titanium resource-rich elements can not become commonly used metals. The first is cost. According to the U.S. market price per pound (1 pound = 0.45 kg) of titanium ingot 8 ~ $ 12, aluminum ingots at $ 1.00 ~ 1.30 / lb, carbon steel is $ 0.20 ~ 0.40 / lb. But the main factor is the active titanium itself extremely difficult to deal with. Furnace atmosphere must Strict control, welding must be carried out in an inert atmosphere. Titanium high activity, low thermal conductivity, large deformation resistance, poor temperature plasticity, deformation process is not only easy to bond with the mold, especially When there is not the tool and the machining is bonded to the abrasive surface tends to thermal processing, the manufacturing lot of the standard structure of titanium scrap debris generated, so-called residual titanium. General forged titanium ingot processing can be Produce 70% of the residual titanium, sometimes up to 90% of this figure. To reduce the burden caused by the high cost, while the development of the residual titanium processing technology, on the other hand the development of near net shape, super plastic forming, precision casting and powder metallurgy and hot isostatic pressing And other high-tech diffusion bonding. Such as processed by milling, shaping, sintering or hot isostatic pressing method of consolidation near net shape powder metallurgy products as parts, material utilization up to 80 %, Both to reduce the material consumption, but also significantly reduces the amount of machining. Another example is the aerospace castings large-scale thin-wall casting technology in titanium alloy, titanium castings performance close to titanium forgings made The reduced by about 50%. The main areas of consumption titanium and titanium alloy is first aviation industry. 1980s, American aviation industry accounts for 74.8% of the titanium with a titanium total amount, Russia, the United Kingdom, also mainly for Aviation Industry, Japan 90% of titanium used in civilian industry. In recent years, titanium used in the aerospace industry in a non-growing aerospace continued to hold the "flagship" status.