The titanium production journey starts with the extraction from different concentrates, one of the most common being rutile. The concentrates are processed, so that the excess of iron is removed. From there, the resulting material is placed in a reactor, along with chlorine gas and carbon.
The next step involves the elimination of impurities, the process being achieved through vacuum distillation. Once the metal chlorides are removed, titanium is purified and the sponge is finally obtained. This will be pressed into blocks and then melted.
Titanium ingots are used for the making of different products, including titanium tubes. Keep on reading and discover more useful information on the process.
Fabrication of titanium products – welded tube
In today’s modern world, more and more companies have shown an interest in the fabrication of titanium products. They possess the necessary technology and equipment to develop titanium tubes, which will be further used by various industries.
The development process has become routine, however, there are certain unique aspects worth taking into consideration. Titanium tubes have to be developed in a perfectly clean environment. In general, there is a separate area reserved for the fabrication of titanium products. It is important that this area does not contain any contaminants, such as dust and grease. Moisture and air drafts have to be absent as well.
Welded titanium tubes have found their use in numerous industries, including the chemical industry. Power plants, especially those that operate in seawater, rely on titanium piping. These tubes are also used for heat exchangers in condensers, being appreciated for their high resistance to corrosion.
Manufacturers might apply additional tension to the titanium tube wall, upon noticing insufficient solidification at the seam of the weld pool. Moreover, in order to ensure that the titanium product remains stable, they might rely on automatic diameter measurement systems. In the future, automatic monitoring systems for seam welding conditions might be introduced as well.
How are titanium tubes formed?
The forming of titanium is achieved at room temperature, the process being similar to the one of steel. Manufacturers rely on the same techniques and equipment, taking into account the unique properties of titanium. This facilitates the tube forming process.
The ductility of titanium, at room temperature, is lower than the one of other structural metals. This automatically translates into a reduced stretch formability and a wider bend radius. Given such characteristics, hot forming is sometimes used, especially if more severe bending is required (or in case of stretch forming).
Titanium’s modulus of elasticity is half the one of steel, which means that the forming process can lead to significant springback (manufacturers will compensate for this characteristic). Also, given the galling tendency of titanium – greater than the one of steel – lubrication is an important part of the tube forming process.
Preparation for forming
In the majority of cases, titanium does not necessitate additional measures to be taken before forming operations. The ingots can be used as they are received but this might not always be valid.
Upon noticing any marks on its surface, such as gouges, these will be removed through different processed (sanding, pickling, etc.). Also, if there are any sharp edges, these should be smoothed out before the actual tube forming process. Otherwise, there is the risk of cracked edges, which will affect the quality of the final product.
Types of forming
Titanium tubes can be formed through two methods: cold and hot forming.
Titanium tubes are formed at a low speed and at room temperature, taking into account the metal’s elongation. For this reason, a tensile test will be performed. The manufacturer will eliminate the springback by using hot sizing on already formed titanium tubes.
It is a known fact that the ductility of titanium – involving bendability and stretch formability – increases with temperature. For this reason, titanium tubes are often realized at high temperatures. It goes without saying that the forming operation of titanium tubes becomes easier with more elevated temperatures. With this method, the springback is practically eliminated on forming grade 5 titanium.
Bending of titanium tubes
Titanium tubes are bent with the use of conventional equipment. The Mandrel tube bending machine is preferred for tight radius bends. In order to minimize titanium’s gail tendency, both the tube bending equipment and the wiper dies must be properly lubricated. For the best results, the bending process should take place at a slow speed.
How is the titanium seamless tube manufactured?
The seamless tube can be developed from commercially-pure titanium or from one of the existent titanium alloys. The titanium ingot is initially processed at a temperature varying between 850 ºC – 1250 ºC, being lastly reduced to 600 ºC – 1100 ºC.
As a result of the processing, a solid billet will be obtained. This will be then turned into a hollow piece, through a piercing process, at a temperature varying between -100 ºC and 1250 ºC.
The size regulation occurs through elongation, followed by a reducing step. This takes a place at a temperature varying between 600 ºC and 1100 ºC, resulting in the reduction of the outside diameter. Last, a sizing step will be taken, at a temperature varying between 550 ºC and 1150 ºC, which will further reduce the outside diameter.
Titanium tubes are manufactured using the same methods and equipment as for other structural metals. With unique characteristics, these are recommended in environments with high corrosion (where steel would not do the job). The aerospace industry uses titanium tubes on a wide basis, recognizing the benefits offered.
Manufacturers can deliver titanium tubes in various sizes, diameters and wall thicknesses. There are different titanium grades available for the tubes, each having different properties to offer and being suitable for various applications. Each titanium grade respects different technical requirements, being suitable for one type of application or another.