There are two isomeric titanium crystals : Below 882 ℃ for the close-packed hexagonal structure α titanium ,
titanium above 882 ℃ for the body-centered sunrui titanium pump cubic β . Alloying elements according to their effect on the phase
transition temperature can be divided into three categories : ① stable α -phase , improving the phase transition
temperature of the elements of α stabilizing element , aluminum , carbon, oxygen and nitrogen . Which aluminum is
the main alloying elements titanium, improving its strength at room temperature and high temperature alloys , lower
specific gravity, increased elastic Sunrui aerospace investment casting modulus have a significant effect . ② stable β -phase, reducing the element of
the phase transition temperature of β stabilizing element , and can be divided isomorphous and eutectoid two . The
former molybdenum , niobium, vanadium, etc. ; latter chromium, manganese, copper, iron , and silicon. ③ small
element of the phase transition temperature of the neutral elements , zirconium and tin .
Oxygen, nitrogen, carbon and hydrogen are the main impurities of titanium . Oxygen and nitrogen in the α phase has
a greater solubility of the titanium alloy has a significant strengthening effect , but the plastic drop. Typically
provide oxygen and nitrogen content of titanium in the 0.15 to 0.2% and 0.04 % to 0.05% or less , respectively . The
solubility of hydrogen in the α phase is very small , titanium dissolved in excess hydride hydrogen will produce
the alloy brittle. Titanium is usually controlled hydrogen content of 0.015% or less. The hydrogen dissolved in the
titanium is reversible , vacuum annealing can be removed .
Titanium has high strength and density and small, good mechanical properties, good toughness and corrosion
resistance. In addition , poor process performance titanium alloys , machining difficulties in thermal processing ,
and very easy to absorb hydrogen nitrogen carbon and other impurities. There are poor abrasion resistance , complex
production process . Titanium industrial production began in 1948 . Requires the development of the aviation
industry , the titanium industry with an average annual growth rate of about 8% growth. Currently the world's
titanium alloy production reached 40,000 tons , nearly 30 kinds of titanium alloys . Is the most widely used
titanium alloy Ti-6Al-4V (TC4), Ti-5Al-2.5Sn (TA7) and commercially pure titanium (TA1, TA2 and TA3).
Titanium is mainly used for the production of aircraft engine compressor components , followed by structure rockets,
missiles and high-speed aircraft. Mid-1960s , titanium and its alloys have been in general industrial applications ,
electrodes for electrolysis industry production , power plant condensers , oil refineries and desalination heater
and environmental pollution control devices. Titanium and its alloys have become a corrosion resistant structural
materials. In addition, for the production of hydrogen storage materials and shape memory alloys.
China began in 1956, titanium and titanium alloys research ; mid-1960s and the development of industrial production
of titanium into TB2 alloys.
Titanium is a new and important structural materials used in the aerospace industry , the proportion between the
aluminum and steel , strength and temperature ranged , but has high strength and excellent resistance than seawater
corrosion and ultra- low temperature performance. In 1950 the United States for the first time in the F-84 fighter-
bombers used after the fuselage insulation panels, wind shield , tail cover other non- load-bearing components.
1960s began using parts from titanium alloy fuselage toward the rear of the fuselage , in part, to replace
structural steel bulkheads , beams, rails and other important flap bearing components . The amount of titanium in
military aircraft is increasing rapidly , reaching 20 % to 25% by weight of the aircraft structure . Since the 1970s
, began extensive use of titanium Sunrui Titanium Casting Golf Heads civilian aircraft such as the Boeing 747 aircraft with a capacity of 3640 kg or
more of titanium . Aircraft Mach number of less than 2.5 primarily to replace the titanium steel , to reduce
structural weight . Again , the U.S. SR-71 high-altitude reconnaissance aircraft speed ( Mach 3 at an altitude of
26,212 meters ) , 93% titanium by weight of the aircraft structure , known as " all-titanium " aircraft . When the
weight ratio of aircraft engines, increased from 4-6 to 8-10 , a corresponding outlet temperature from compressor
200 ~ 300 ° C to 500 ~ 600 ° C , the original plate is made of aluminum and the blades of the low pressure
compressor must switch to titanium , or titanium instead of stainless steel plate and high-pressure compressor
blades in order to reduce the structural weight . 1970s, the amount of titanium in the general aviation engines
accounted for 20% to 30% of the total weight of the structure is mainly used in the manufacture of compressor
components such as forged titanium fan, compressor discs and blades, cast titanium compressor casing , intermediate
casing, bearing housing and so on. The main advantage of the spacecraft 's high- strength titanium alloy , corrosion
resistance and low temperature performance to manufacture all kinds of pressure vessels, fuel tanks , fasteners,
instrument straps, architecture and rocket shells. Sputnik , the lunar module , manned spaceship and space shuttles
are also using titanium plates welded .
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