titanium pipe production method and application
Titanium seamless pipe
Titanium pipe is mainly divided into seamless pipe and welded pipe. At present, the cold rolling vacuum annealing process is widely used in the production of titanium seamless tubes in the market, the ingot is made into tube blank by forging bar blank, and the tube is finally made into titanium tube by multi pass rolling and annealing process. There are mainly two manufacturing processes for the tube blank. One method is drilling and extrusion to produce the tube blank, which consumes a large amount of titanium and has a uniform wall thickness. The selection of appropriate glass lubricant is the key in the extrusion, and requires a large tonnage extruder, which requires a large amount of equipment investment; The other method is the cross rolling piercing method commonly used in steel pipe production. This method has small titanium consumption, slightly larger thickness tolerance of pipe blank, and sometimes the penetration is not transparent during the piercing process, and the plug is stuck in the blank, which is a technical problem worthy of study in the current production technology.
Although the processing technology of titanium alloy seamless pipes is relatively mature, due to the limitations of existing equipment, the main materials of titanium pipes are low-strength, low alloyed pure titanium, titanium molybdenum nickel and other low-strength titanium pipes, and the processing technology is still cold rolling. However, the production of medium and high strength titanium alloy pipes, such as Ti6A14V pipes, needs to adopt warm rolling technology, that is, install induction heating device on the pipe mill. It can be seen that in the future, with the large-scale equipment, the gradual improvement of auxiliary equipment and the continuous optimization of technology, large-scale seamless pipes and some alloy pipes will be mass produced and widely used.
The existing titanium seamless pipe production process is mature and the product supply is stable. However, for pipes with special requirements, the production of titanium seamless pipe is difficult, such as titanium and titanium alloy thin-walled pipes, and ultra long titanium pipes with a length of more than 14m; At the same time, the production of titanium seamless tubes requires many tools, abrasives and complex equipment, resulting in limited production capacity and long production cycle of manufacturers, which can not meet the large demand of the market for thin-walled tubes, ultra long tubes and low-cost tubes.
Titanium welded pipe
Based on the above shortcomings of titanium seamless pipe, titanium welded pipe came into being. At present, large titanium Welded Pipe Companies in the world include Japan iron and steel company and Kobe Steel Company, valtimet company of France, vsmpo company of Russia, etc. In the mid-1980s, Baoji Nonferrous Metal processing plant introduced the titanium welded pipe production line from the United States. Since then, the history that China can not produce titanium welded pipe has ended. The main factor restricting the development of titanium welded pipe in China is the poor production technology of titanium strip. Until 2005, initiated by BaoTi Co., Ltd., French valtimet company provided technical support, and American timet company supplied titanium coil raw materials, the three companies jointly funded the establishment of Xi'an BaoTi Meite Farino Welding Pipe Co., Ltd., and established two fully automatic welding pipe production lines estimated to be advanced. The company has become a leading enterprise of titanium welding pipe in China. In recent years, with the development of China's power industry, 2000MW 25.4mmx 0.5mm 25.4mmx0.7mm titanium tubes are about 25t. This part of titanium tubes basically use titanium welded tubes. Facing a large number of market demands, it is urgent to solve the technical problems of titanium coil production in China.
Titanium welded pipe is a relatively unique titanium pipe product. Its production process is welded by tungsten inert gas shielded welding after the cold rolled titanium coil supports the pipe shape. Since titanium material has excellent seawater corrosion resistance, titanium welded pipe has gradually replaced stainless steel and copper alloy pipe as the preferred material for condensers and heat exchangers since the product was put into the market. Therefore, it is widely used in condensers and heat exchangers that need seawater as cooling medium, such as coastal power stations, seawater desalination, offshore oil, etc. Compared with titanium seamless pipe, titanium welded pipe can be used to manufacture pipe fittings with thinner wall thickness, which can reach 0.3mm-0.5mm, while the minimum wall thickness of titanium seamless pipe is about 0.9mm; At the same time, titanium welded pipe has high utilization rate of raw materials, high production efficiency and good economic benefits.
In developed countries, welded tubes in condensers and condensers in coastal power stations and nuclear power stations gradually replace titanium thin-walled seamless tubes. There are many studies on the comparison of expansion performance, pressure resistance and fatigue resistance between titanium welded tubes and seamless tubes. The results show that the welding quality of welded tubes can meet the harsh service environment at present. Due to the low yield of seamless pipe, long production cycle and high cost, while the production process of pure titanium welded pipe is short, the production cost is low and the production efficiency is high, vigorously developing welded pipe is a development trend.
