Titanium Tube Classification
According to the production method, titanium alloy pipes are divided into two categories: seamless pipes and welded pipes.
Titanium alloy seamless pipes are classified by diameter:
• Large diameter seamless pipes: nominal diameter greater than 200mm;
• Small diameter seamless pipes: nominal diameter less than or equal to 200mm.
For seamless pipes of different diameters, the process selection is very different, starting from the production of pipe billets at the source.
Tube Embryo Production
The tube billet is the "prototype" of a titanium alloy seamless tube. The main production methods are the piercing extrusion method and the oblique rolling piercing method.
1. Piercing Extrusion
This method involves directly extruding a titanium ingot heated to a specific temperature into a hollow cup-shaped body in an extrusion cylinder under lubrication. Its advantages are significant: it can produce tube billets of various specifications, not limited to a single size. The large deformation during extrusion can break up grains and achieve "fine-grain strengthening." It can also utilize triaxial stress to form tube billets from metals with poor plasticity. However, its disadvantages are also significant: high metal consumption, significant mold wear, complex equipment, high investment costs, and difficulty in ensuring product surface quality.
2. Cross-rolling Piercing Method
Unlike the piercing and extrusion method, cross-rolling piercing uses rollers and fixed guides to rapidly pass the titanium alloy billet through a fixed mandrel, resulting in a seamless tube billet. Its core advantage is its high cost-performance ratio:
• Low cost: Minimal metal and die loss, simple equipment, and low investment, resulting in production costs only 50%-70% of those of the piercing and extrusion method;
• Easy operation: Low lubrication requirements and guaranteed surface quality.
However, its limitations are also clear: the produced tube billets are limited in specifications, lack flexibility, and have low deformation tolerances, making it impossible to produce thinner-walled tube billets.
Rolling
After the tube billet is finished, it must undergo rolling to become a qualified titanium alloy seamless tube. Rolling conditions are categorized into hot rolling and cold rolling.
• Hot rolling: Rolling the tube billet below the recrystallization temperature has significant disadvantages-significant wear on the mill passes and rolls, and poor dimensional accuracy. It is no longer a mainstream option.
• Cold rolling: Rolling at room temperature offers significantly higher dimensional accuracy than hot rolling and is currently the preferred method for producing titanium alloy seamless tubes.
Process Parameters
Rolling parameters directly impact the strength, plasticity, and surface quality of titanium alloy seamless pipes. Three key parameters are crucial:
1. Deformation
Deformation affects rolling force, surface quality, and microstructure. For Ti-1300 titanium alloy pipes, increasing the cold rolling deformation from 20% to 30% increased the tensile strength from 1207.5 MPa to 1223.5 MPa.
elongation increased from 12.75% to 13.25%.
2. Feed
A too low feed rate results in low production efficiency; a too high feed rate can easily lead to defects such as flash, ovalization, and uneven wall thickness, seriously impacting quality. Precise control is essential.
3. Rolling Passes
It is rare to produce pipes of the desired specifications in a single pass; multiple rolling passes are usually required. Reducing the deformation per pass results in a more uniform wall thickness. Excessive passes increase production costs, and inclusions generated during rolling can impair surface quality.
Summary
V. Summary
The above briefly describes the process flow for producing titanium alloy seamless pipes. You can see that the process selection for seamless pipes of varying diameters and wall thicknesses is a comprehensive evaluation process. We will select the most cost-effective solution for our customers. If you require further information, please contact us through the following channels.
Name: Tina
Position: Manager
Email: W-Mo@titanmsgp.com
Tel: +86 15091084744
