Titanium alloy pipes are divided into seamless pipes and welded pipes.
Titanium alloy seamless pipes are generally processed by extrusion + rolling or diagonal rolling piercing + rolling. Hot extrusion is a plastic processing technology that uses the principle of plastic material deformation to use a die to make a titanium alloy blank into a material with a certain shape, thickness and performance in a hot state. It is a complex process that combines plastic deformation and flow deformation. The material is in a state of three-way compressive stress during extrusion, which is beneficial to the plasticity of the material. The economic pressing process mainly uses rice to produce seamless pipes, bars and profiles for drinking gold. The main processing parameters of the extrusion process include extrusion ratio, extrusion temperature, extrusion speed and so on. When extruding the tube, a hollow tube made of titanium alloy loose material through deep hole processing or hot pressure perforation is also used as the original blank. The size of the hollow tube blank is determined by the inner diameter of the extrusion barrel of the extruder. Due to the high viscosity of drink alloys, copper, mild steel or other metals are usually covered during extrusion, or the surface of titanium alloy is covered with grease, glass lubricant, etc. for extrusion. Through extrusion, titanium alloy thick-walled pipes or titanium alloy pipes that do not require high dimensional accuracy can be directly prepared. High-precision alloy seamless pipes are generally produced by rolling technology. The billets are generally extruded pipe blanks. Commonly used pipe rolling methods include two-half pass cold rolling, two-roll ring pass cold rolling, and multi-roll cold rolling. Rolling, two-target warm rolling and multi-roll warm rolling, etc. For pure titanium with low strength and high plasticity, it is generally produced by cold rolling. The deformation of the pass is generally controlled at 20% to 60%. Annealing treatment is required between passes to eliminate work hardening and restore plasticity. For medium and high-strength titanium alloys, due to high tensile strength, large deformation resistance and poor processing plasticity: the warm-drying technology must be used when rolling seamless pipes, that is, induction heating devices or flame heaters are installed on the rolling mill. The heating temperature is controlled at about 100°C below the recrystallization temperature.
For large-diameter thick-walled titanium composite pipes: generally, the skew-rolling piercing method is also used for production. The cross-rolling piercing method uses tensile stress along the weave and transverse directions of the rolled blanks to cause micro-cracks in the core area of the circular material, and then expand into a loose area. The use of high-temperature-resistant plugs enables the plastic deformation of the metal in the loose area: direct forming of the tube from the city. The heating temperature of the billet in this method is higher, which is beneficial to improve the new cracking properties of the pipe to achieve the purpose of high production efficiency, high material utilization rate and low production cost. Titanium alloy welded pipes are generally produced by welding, and welded pipes are produced with high precision A very efficient method for thin titanium alloy pipes: its production process is: titanium strip coil slitting → forming → welding → shaping and sizing ~ heat treatment straightening eddy current/ultrasonic inspection → airtight inspection of finished welded pipes. The production process is generally continuous production: The product quality has high stability, and the pipes produced are generally used for heat exchangers, condensers, etc.
