TC4 titanium alloy
TC4 titanium alloy is an α-β titanium alloy successfully developed by the United States in 1954, containing 6% of α-stable elements and 4% of β-stable elements V. The aluminum equivalent of the nominal composition of TC4 titanium alloy is 7.0, the molybdenum equivalent is 2.9, and the annealed state contains 10%-15% β phase. Al in the Ti-Al-V system improves the room temperature strength and hot strength properties of the alloy through solid solution strengthening α phase, and V is one of the few alloying elements in titanium alloys that can improve both strength and plasticity. The beneficial effect of V on the plasticity of titanium alloys is that it does not increase the ratio of the c/a axis of the α-state lattice like most alloying elements, but reduces the ratio, thereby improving the formation of α-phase and avoiding long-term use. Alloy embrittlement occurs during the process.
The main features of TC4 titanium alloy are excellent comprehensive performance and good process performance. TC4 titanium alloy has medium room temperature strength and high temperature strength, good creep resistance and thermal stability, high fatigue resistance and crack growth resistance in seawater, and satisfactory fracture toughness and hot salt stress corrosion resistance. The sensitivity to hydrogen is also smaller than that of TC2 and TC1 alloys, and it is suitable for the manufacture of various parts working in a wide temperature range of -196~450 °C, especially the parts designed with the principle of damage tolerance limitation. TC4 titanium alloy also has excellent process plasticity and superplasticity, suitable for forming by various pressure processing methods, and adopts various methods for welding and machining.
The main semi-finished products of TC4 titanium alloy are rods, forgings, thin plates, thick plates, profiles and wires, etc., and are also used for castings (ZTC4).
TC4ELI titanium alloy
TC4ELI is an improved version of TC4, the main difference is different Al content and lower content of interstitial elements Fe, N, H, O.
TC4ELI titanium alloy has become a medical surgical implant because of its good biocompatibility, low elastic modulus, low density, good anti-corrosion performance, non-toxicity, high yield strength, long fatigue life, large plasticity at room temperature, and easy forming. ideal material for things. Medical TC4ELI titanium alloy plates are mainly used for skull repair and bone grafting, which have higher requirements for its strength, fatigue life and plasticity.
Titanium alloy is an alloy composed of titanium element and other elements. Titanium has two kinds of allotropic crystals: titanium is an allotropic isomer with a melting point of 1668°C, and it is a close-packed hexagonal lattice structure when it is lower than 882°C, called α-titanium; it is a body-centered cubic structure above 882°C lattice structure, called β-titanium. Utilizing the different characteristics of the above two structures of titanium, adding appropriate alloying elements to gradually change the phase transition temperature and component content to obtain titanium alloys with different structures.
On the basis of TC4 alloy, TC4 ELI titanium alloy reduces the content of interstitial elements C, O, N and impurity element Fe, and the strength is reduced, but the capacity and toughness can be significantly improved. TC4 ELI has good plasticity, toughness, good welding performance and low temperature performance, and is widely used in important fields such as low temperature engineering, medical treatment, ships and aircraft.
TC4 alloy can be used in ordinary environment or high temperature environment, TC4ELI alloy can be used in ultra-low temperature environment
Similar grades of TC4 titanium alloy and TC4ELI titanium alloy are: T-6A-4V/Grade 5 (American grade), BT 6 (Russian grade), IMI 318 (British grade), TiAI6V4 (German grade).
Medical equipment is manufactured in the human body due to trauma and tumor-induced bone and joint damage. Titanium and titanium alloys are used to manufacture artificial joints, bone plates and screws, which have been widely used in clinical practice. Also used in hip joints (including femoral head), knee joints, elbow joints, metacarpophalangeal joints, interphalangeal joints, mandibles, artificial vertebral bodies (spinal orthoses), pacemaker housings, artificial hearts (heart-shaped valves) , artificial implants, titanium-nickel orthodontics, and titanium mesh in cranial plastic surgery, etc.
Due to the characteristics of high specific strength, biocompatibility and good corrosion resistance of body fluids, titanium and titanium alloys are attracting more and more attention.
Ti 6Al-4V ELI is a grade of Ti 6Al-4V with a smaller interstitial structure, so that it can achieve maximum toughness and is suitable for seawater and low temperature environments. This grade of alloy is usually used in the annealed condition. Ti 6Al-4V is a better material of choice in the field of medical implants.
The production process is: medium relaxation annealing at 900-120 degrees Fahrenheit for 1-4 hours, and air cooling. Double annealing, round bars and forgings: solution anneal at 50-100°F beta transition temperature, hold at least 1 hour, air cool, then reheat at 1300-1400°F, hold at least 1 hour, air cool . Relaxation annealing is suitable after welding.
