The core processes of titanium finned tubes are divided into three categories: integral rolling, high-frequency welding, and laser welding. Among them, integral rolling is the mainstream process for titanium materials, balancing corrosion resistance and heat transfer efficiency; high-frequency welding is suitable for large-scale mass production; and laser welding is used in high-precision and high-reliability scenarios. The following provides a detailed introduction and comparison of these processes.

       1. Overall rolling process (mainstream process for titanium finned tubes)

Process Principle

       By utilizing plastic deformation of titanium tubes, continuous fins are directly rolled onto the surface of the base tube using specialized rollers, forming an integral structure without additional welding layers. This results in low contact thermal resistance and high heat transfer efficiency.

core process

       Substrate pretreatment

       Base tube: TA1/TA2 seamless titanium tubes (GB/T 3625/ASTM B338) are selected, straightened, pickled/sandblasted to remove oxide scale, and degreased to ensure a clean surface.

       Finned formation: Titanium strip is unrolled, leveled, deburred, and cut to the designed size.

       Rolling forming

       The titanium tube is inserted into the mandrel and continuously rolled by multiple sets of rollers, causing plastic deformation of the tube metal to form fins (spiral/straight ribs).

       Control the rolling pressure, speed, and temperature to ensure uniform fin height, fin spacing, and tooth spacing (common tooth spacing is 19–42 teeth per inch, and fin height is 0.5–3mm).

post-processing

       Cooling, cutting to length, straightening;

       Non-destructive testing (eddy current/hydrostatic pressure) to ensure uniform wall thickness and absence of cracks;

       Surface passivation treatment restores the TiO₂ passivation film, enhancing corrosion resistance.

       Advantages and Applications

       Advantages: integrated structure, low thermal resistance, excellent corrosion resistance, thermal shock resistance, and pressure resistance;

       Application: Seawater desalination, chlor-alkali chemical industry, shipbuilding and marine, nuclear power, and other highly corrosive working conditions.

       II. High-frequency welding process (mass production process of titanium finned tubes)

Process Principle

       The contact surface between the titanium tube and the titanium fin is rapidly heated to a plastic state through high-frequency induction heating (150–450kHz), forming a metallurgical bond under pressure without the filling of solder.

core process

       Substrate pretreatment: Similar to the overall rolling process, the focus is on controlling the surface cleanliness of the titanium tube to avoid the impact of oxide film on welding.

       Finned formation and feeding: Titanium strip is rolled into spiral fins, which are precisely fitted to the rotating titanium tube. The feeding speed is synchronized with the tube speed.

high-frequency welding

       The gap between the induction coil and the tube body is 1-3mm, with closed-loop temperature control to adjust power and avoid overburning;

       The pressure roller applies a radial pressure of 0.5–2 MPa to ensure tight bonding between the fins and the tube body;

       Welding time is 0.1–1 second, resulting in a continuous weld seam.

       Post-processing: Air cooling/water cooling, pipe cutting, eddy current inspection, hydrostatic test, passivation.

       Advantages and Applications

       Advantages: high production efficiency, low cost, high weld strength;

       Application: Large-scale production scenarios such as chemical heat exchangers and flue gas coolers.

       III. Laser welding process (high-precision process for titanium finned tubes)

Process Principle

       By focusing a laser beam to generate high temperatures, the contact surface between the titanium tube and the fins is melted to form a molten pool. After rapid cooling, metallurgical bonding is achieved, resulting in a high-precision weld seam with a small heat-affected zone.

core process

       Substrate pretreatment: Strictly remove oil and perform acid pickling to ensure the surface is free of impurities;

       Finned assembly: The fins are precisely aligned with the titanium tubes, with a gap controlled between 0.05–0.1mm;

laser welding

       Laser power: 1–5kW, welding speed: 0.5–3m/min;

       Protective gas (argon) prevents titanium from oxidizing;

       Form continuous or spot welds to ensure sealing performance and bonding strength.

       Post-processing: straightening, non-destructive testing, passivation.

       Advantages and Applicability

       Advantages: high weld accuracy, small heat-affected zone, stable corrosion resistance;