Key Technologies in the Production of Titanium Welded Pipes

1. Welding Technology 

Selection of Welding Methods

Commonly used welding methods include Tungsten Inert Gas (TIG) welding and Plasma Arc Welding (PAW). TIG welding features a stable arc and high weld quality, enabling effective control of welding heat input, and has a good welding effect on thin-walled titanium welded pipes. PAW has a high energy density and strong penetration ability, which is suitable for thick-walled titanium welded pipes or situations where welding speed is required. 

Control of Welding Parameters

Parameters such as welding current, voltage, and welding speed directly affect the quality of the weld. Appropriate welding current and voltage can ensure the penetration depth and width of the weld. The welding speed needs to be adjusted according to the wall thickness of the pipe and the welding method to avoid welding defects. For example, when welding thin-walled titanium welded pipes, an excessively high welding speed may lead to incomplete penetration, while a too slow speed may cause the weld to overheat and generate defects such as porosity. 

Use of Shielding Gas

Since titanium is highly reactive with elements such as oxygen, nitrogen, and hydrogen in the air at high temperatures, inert shielding gas (such as argon) is required during welding. The flow rate, purity, and coverage effect of the shielding gas are crucial for preventing the oxidation of the weld. Generally, it is necessary to ensure that the shielding gas can fully cover the welding pool and the heat-affected zone, and the purity should meet high standards. 

2. Tube Forming Technology 

Selection of Forming Methods

The forming of titanium welded pipes mainly includes roll bending forming and extrusion forming. Roll bending forming gradually bends titanium strip into a tubular shape through a series of rolls. This method has high production efficiency and relatively high product precision, and is suitable for large-scale production. Extrusion forming extrudes titanium billets into pipes in molds. It can produce pipes with complex shapes or special specifications, but its efficiency is relatively low. 

Control of Forming Precision

During the tube forming process, it is necessary to ensure the precision indexes such as roundness and wall thickness uniformity of the tube. By precisely adjusting parameters such as the spacing, angle, and pressure of the rolls, the forming quality of the tube can be effectively controlled. For example, during roll bending forming, if the roll spacing is uneven, it may lead to excessive deviation in the wall thickness of the tube. 

3. Heat Treatment Technology 

Elimination of Welding Stress

After welding, titanium welded pipes will generate welding stress, which may lead to problems such as pipe deformation and weld cracking. Through appropriate heat treatment processes, such as annealing treatment, welding stress can be effectively eliminated and the weld microstructure can be homogenized. Generally, online annealing or offline annealing is adopted, and parameters such as annealing temperature, time, and cooling rate are determined according to the material, wall thickness, and welding process of the pipe. 

Improvement of Material Properties

Heat treatment can also improve the comprehensive properties of titanium welded pipes, such as increasing their strength, toughness, and corrosion resistance. For example, through a combination of solution treatment and aging treatment, titanium alloy welded pipes can obtain better mechanical properties and corrosion resistance. 

4. Quality Inspection Technology 

Non-destructive Testing Technology

It includes eddy current testing, ultrasonic testing, etc. Eddy current testing is mainly used to detect surface and near-surface defects of pipes, such as cracks and porosity. Ultrasonic testing can detect internal defects of pipes and determine the location and size of the defects. These non-destructive testing technologies can ensure product quality without damaging the pipes. 

Dimensional Precision Inspection

Tools such as laser diameter measurement and calipers are used to accurately measure the outer diameter, inner diameter, wall thickness and other dimensions of the pipes. This is very important for ensuring that the pipes meet the standard requirements and meet the needs of different users.