Difference between TC4 and TC4ELI titanium alloys

TC4 titanium alloy
TC4 titanium alloy is an α-β type titanium alloy successfully developed by the United States in 1954, containing 6% of α stabilizing element and 4% of β stabilizing element V. The nominal composition of TC4 titanium alloy has an aluminum equivalent of 6.0, a vanadium equivalent of 4.0, and an annealed state containing 10%-15% of β-phase. Al is strengthened by solid solution strengthening of α-phase in the Ti-Al-V system to increase the alloy's room-temperature strength and hot-strengthening properties, and V is one of the few alloying elements in titanium alloys that can both increase strength and improve plasticity. V is one of the few alloying elements in titanium alloys that improves both strength and plasticity.The favorable effect of V on the plasticity of titanium alloys is due to the fact that it does not increase the ratio of the c/a axis of the α-state lattice, as is the case with most alloying elements, but rather decreases it, thus increasing the formation of the α-phase and avoiding alloy embrittlement during prolonged service.
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 extension resistance in seawater, as well as satisfactory fracture toughness and resistance to hot salt stress corrosion, the sensitivity to hydrogen is also smaller than TC2, TC1 alloys, and it is suitable for the manufacture of- 196~450 ℃ wide range of alloys. 196 ~ 450 ℃ wide temperature range of work in a variety of parts, especially using the principle of damage tolerance limit the design of parts.TC4 titanium alloy also has excellent process plasticity and superplasticity, suitable for molding with a variety of pressure machining methods, and a variety of ways to weld and machining.
The main semi-finished forms of TC4 titanium alloys are bars, forgings, sheets, plates, profiles and wires, etc. They are also used for castings (ZTC4).
TC4ELI titanium alloy
TC4ELI is a modified version of TC4, the main difference being the different Al content and the lower content of the interstitial elements Fe, N, H and O. The main difference is that TC4ELI is a modified version of TC4.

TC4ELI titanium alloy has become an ideal material for medical surgical implants due to its good biocompatibility, low modulus of elasticity, low density, good corrosion resistance, non-toxicity, high yield strength, long fatigue life, high plasticity at room temperature, and ease of molding. Medical TC4ELI titanium alloy sheet is mainly used for cranial bone repair, bone grafting, etc., which has higher requirements for its strength, fatigue life, plasticity and so on.
Titanium alloy is an alloy composed of titanium as the base and other elements. Titanium has two kinds of homogeneous and heterogeneous crystals: titanium is a homogeneous elemental isomer, with a melting point of 1668℃, and a dense row hexagonal lattice structure, known as α-titanium, when it is lower than 882℃, and a body-centered cubic lattice structure, known as β-titanium, when it is above 882℃. The use of titanium's different characteristics of the above two structures, add the appropriate alloying elements, so that the phase transition temperature and component content gradually change and get different organizations of titanium alloys (titanium alloys).
TC4 ELI titanium alloy in the TC4 alloy on the basis of reducing the gap element C, O, N and the content of impurity elements Fe, the strength has been reduced, but can significantly improve the toughness. TC4 ELI has good plasticity, toughness, good welding performance and low temperature performance, widely used in cryogenic engineering, medical care, ships and aircraft and other important areas.
TC4 alloy can be used in ordinary environment or high temperature environment, TC4ELI alloy can be used in ultra-low temperature environment.
TC4 titanium alloy and TC4ELI titanium alloy similar grades are: T-6A-4V/Grade 5 (U.S. grades), BT 6 (Russian grades), IMI 318 (British grades), TiAI6V4 (German grades).
Medical equipment manufacturing in the human body due to trauma, tumors caused by bone and joint injuries, the use of titanium and titanium alloy manufacturing artificial joints, bone plates and screws, is now widely used in clinical practice. Also used in hip joints (including the femoral head), knee joints, elbow joints, metacarpophalangeal joints, interphalangeal joints, mandible, artificial vertebrae (spinal orthosis), cardiac pacemaker shells, artificial heart (heart valves), artificial dental implants, titanium-nickel orthodontic teeth and titanium mesh in the cranial plastic surgery and so on.
Titanium and titanium alloys are gaining importance due to their high specific strength, biocompatibility and resistance to corrosion by body fluids.

Ti 6Al-4V ELI is a grade of Ti 6Al-4V with smaller gaps, which allows for maximum toughness for seawater and low temperature environments. This grade is typically used in the annealed condition and Ti 6Al-4V is a good choice for medical implants.
The production process consists of relaxation annealing at 900-120 degrees Fahrenheit for 1-4 hours and air cooling. The process for double annealing, round bars and forgings is: solution anneal at 50-100 degrees F beta transformation temperature, hold for at least 1 hour and air cool, followed by reheating at 1300-1400 degrees F, hold for at least 1 hour and air cool. Relaxation annealing is suitable after welding.