TC4 coefficient of thermal expansion TC4 titanium alloy has a series of advantages such as excellent corrosion resistance, small density, high specific strength, good toughness and weldability, and has been successfully applied in aerospace, petrochemical, shipbuilding, automobile, pharmaceutical and other sectors. Titanium is an allotrope that can be divided into -ti and -ti with a transition temperature of 8825 , The crystal structure of titanium below this temperature is a close-packed hexagonal (HCP) structure, which is called -Ti;Above this temperature, the crystal structure of titanium transforms into a body-centered cubic (BCC) structure. 
Mechanical properties of TC4 titanium alloy tensile strength B MPA 895 specifies the residual elongation stress R02 MPa 825 elongation δ5 (%)10 section shrinkage (%25 titanium alloy in the annealed state of phase composition, can be divided into three categories, namely type, type and ( + type titanium alloy, its grade is composed of the letter t+(a, b, c) + number, which is also the most widely used titanium alloy classification method in domestic production practice. TC4 titanium alloy density 45 (g cm3) operating temperature -100 550 ( ).
Titanium alloys: These types of titanium alloys include commercially pure titanium (Ta1, Ta2 and Ta3) and titanium alloys alloyed with the addition of phase-stable elements and both phase-stable and neutral elements. It is phase at room temperature and high service temperature, and its main characteristics are stable structure, good corrosion resistance, wear resistance and weldability, and good oxidation resistance. The main disadvantage is that the strength is low at room temperature and cannot be strengthened by heat treatment. The chemical composition of TC4 titanium alloy contains titanium (Ti) and residual iron (Fe) 030 C(c) 010 Nitrogen (N) 005 Hydrogen (h) 0015 Oxygen (O) 020 aluminium (Al) 55～6.75 vanadium (v) 35～4.5
The commonly used grades in the industry are industrial pure titanium and TA7, of which industrial pure titanium is mainly used to manufacture seawater desalination devices and aircraft skinsThe TA7 is mainly used to make components such as air shields for engines and missile fuel tanks for supersonic aircraft.