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Properties of titanium

Properties of titanium

  Evek GmbH  

 (2044)    (3)    0

  metal

TITAN (DE)

Titanium is a solid and durable silver-colored metal, which is characterized by high corrosion resistance and the ability to withstand heating to high temperatures. The combination of these features makes titanium rolling material into a strategically important and indispensable material in the manufacture of missiles in aircraft and shipbuilding, the automotive industry and in the transport industry.

Properties of titanium and rolled titanium

Due to the melting point (from 1665 ° C to 1671 ° C), titanium is considered a refractory metal. However, the melting point is higher for tantalum, tungsten, zirconium and molybdenum. It is not magnetized in a magnetic field, ie this element has paramagnetic properties.

Titanium is four times harder than copper and iron, more than ten times harder than aluminum. This shows the strength of the metal, its ability to withstand deformation and destruction. And an increase in the yield strength leads to an increase in the resistance of titanium equipment to loads. The corrosion resistance of rolled titanium products is also great. Platinum is not inferior here. It is very resistant to cavitation. Namely: Air bubbles that occur due to the active movement of titanium parts in the working fluid do not destroy them.

Titan has a high strength (140 kg / mm²). It is comparable to that for alloyed steels. In terms of density, titanium with an indicator of 4.5 g / cm³ lies in the gap between 2.7 g / cm³ aluminum and 7.8 g / cm³ iron, but significantly exceeds these in its mechanical properties. Density, strength almost do not change with a significant rise in temperature.

Titan has an interesting quality called "memory". It is the fact that in alloys with nickel, hydrogen, etc. it can "remember" the configuration of the part made at a certain temperature. After being deformed, the part changes and may remain in this shape for a long time, but when it is reheated (to the temperature of the original manufacture), it restores its original shape.

Titanium, which is rolled, conducts heat and electricity poorly because of its low linear expansion and thermal conductivity. In the low temperature range, however, it can transfer energy over long distances, ie it is a superconductor. Titan also has a high electrical resistance coefficient. The metal has improved anti-corrosion properties. Since it is an active chem. Element, an oxide film is formed on its surface. It protects the metal from further exposure to air, water and aggressive working environments (including dilute, concentrated nitric acid).

The interaction with sulfuric and hydrochloric acid at a temperature of around 20 ° C is weak, but increases with increasing temperature. The result is chlorides and sulfates. The reaction with phosphoric and nitric acid is weak. Titan reacts with halogens. The interaction with chlorine occurs at temperatures above 300 ° C. When interacting with nitrogen, a brown-yellow nitrate film forms on the metal surface. The reactions of titanium with various elements are more active the higher the temperature of the reactants. The ignition of titanium is observed at 1200 ° C. When ignited, it glows brightly.

The reaction with hydrogen, which occurs at temperatures above 20 ° C, leads to an active absorption of hydrogen. In addition, one gram of metal can absorb up to 400 cm³ of hydrogen. Metal can be processed hot and cold. It can be drawn into a wire, rolled into a ribbon or a film and rolled out up to 0.01 mm in the form of a film.

Physical properties of titanium:

  • Normal state: fixed
  • Color: silver white
  • Melting point: 1720 ° C.
  • Molar volume: 10.64.10-6 m³ / mol
  • Density: 4,507 g / cm³
  • Conductivity: 2.34.106Sm / m
  • Thermal conductivity: 21.9 W / (mK)
  • Thermal expansion coefficient: 8.5.10-6 / ° C.

Advantages disadvantages

Advantages:

  •      A low density (4500 kg / m3) helps to reduce the mass of the manufactured products.
  •      high mechanical strength. It should be noted that titanium alloys are superior in strength to aluminum and magnesium at elevated temperatures (250-500 ° C);
  •      unusually high corrosion resistance due to the ability of Ti to form thin (5-15 μm) continuous TiO2 oxide films on the surface that are strongly bonded to the metal mass;
  •       The specific strength (ratio of strength to density) of the best titanium alloys reaches 30-35 or more, which is almost twice the specific strength of alloy steels.

       Disadvantage:

  • T i is much more expensive than iron, aluminum, copper and magnesium due to its high production costs.
  •         active interaction at high temperatures, especially in the liquid state, with all gases that make up the atmosphere, which means that Ti and its alloys can only be melted in a vacuum or inert gas;
  •          Difficulties in the production of titanium waste;
  •          poor anti-friction properties due to the adhesion of Ti to many materials; Titanium paired with titanium cannot act on friction at all;
  •           high tendency of Ti and many of its alloys towards hydrogen embrittlement and salt corrosion;
  •           poor machinability by cutting similar to the machinability of austenitic stainless steels;
  •           High chemical activity, a tendency for grain growth at high temperatures and phase changes during the welding cycle cause difficulties when welding titanium.

The most popular types of rolled titanium products on the modern    Metal rolling market:

  •          Titanium tape;
  •          Titanium plates;
  •          Titanium tubes;
  •          Forgings made of titanium;
  •          Titanium wire;
  •          Titanium rods.

Four types of commercially pure titanium (1/2/3/4) are used when good forging properties are required, combined with excellent corrosion resistance, medium strength and good weldability. Limited inclusions - iron, oxygen and nitrogen - and their different levels determine the mechanical properties of the brand, from softer and forged (grade 1) to harder and stronger (grade 4).

Grade 1 titanium has the best formability and formability of four types and excellent corrosion resistance in acidic environments or in the presence of chlorides. This brand has good strength even at low temperatures and can be easily welded, machined, deformed at low or high temperatures.

Titan Grade 2 is very popular due to its wide range of applications and high availability. It has the same properties as Titanium Grade - 1, but the mechanical properties are much higher. The corrosion resistance is approximately the same.
This steel has good weldability, strength and ductility as well as good formability. The most popular products of this steel are sheets and bars.

Titan Grade 3 is characterized by increased strength and moderate ductility. The material is easy to weld. This material is very corrosion-resistant in oxidizing and very weakly reducing environments. The alloy is pourable and is often used in the manufacture of cast valves and fittings.

Titan Grade 4 is an unalloyed titanium grade according to the American ASTM standard. It differs from the more general grade 2 brand in that it has higher strength properties and a relatively high ductility. Grade 4 sheets and plates are used in products where the strength and purity of titanium are important.

Titan Grade 5 (UNS R56400) has an alpha beta crystal structure and is the most commonly used alloy in the Ti family. The addition of elements V and Al makes it stronger than other commercially pure titanium, while maintaining the same hardness. Titan Grade 5 is primarily used in aerospace components.

 (2044)    (3)    0

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