The Requirements For The Welding Process Of Gr23 Titanium Welded Pipes.
Mar 25, 2024
Titanium pipes have high strength, excellent plastic toughness and corrosion resistance, and are widely used in aerospace, shipbuilding and chemical plants. To better utilize titanium pipes, you must be skilled in its weldability.
The following GNEE introduces how to master titanium welded pipe to connect titanium pipe welding materials.
Welding wire: ERTi-2; welding method: GTAW (manual tungsten argon arc welding)
Protective gas: with a purity of 99.995%, the water content should not be greater than 50Mg%m3 of argon, the welded molten pool and welded joints inside and outside the surface temperature higher than 400 ° C area are used argon protection.
Titanium pipe welding preparation
1) Bevel processing
After cutting the titanium pipe, the bevel is polished with an aluminum oxide grinder, and the processed bevel does not allow overheating and discoloration of the base material.
2) Bevel and wire cleaning
A. Clean the internal and external surfaces within 50mm of the bevel and its sides, and the cleaning procedure is as follows:
Grinder grinding → sandpaper wheel polishing → acetone cleaning.
Cleaning can not be directly after the welding operation, wait until the bevel end face to dry before you can work. If left for more than 2 hours, the bevel must be re-cleaned or protected with self-adhesive tape and plastic sheeting.
B. Welding wire is also wiped with a sponge moistened with acetone and stored in a special welding wire box.
c. The operator must wear clean gloves during the welding process.
Titanium pipe welding process specification
1) Welding specifications
2) Welding should be in the qualified process parameters within the scope of the choice of small wire energy welding, generally controlled in 6 ~ 35KJ / cm, should be used in small current, slow welding.
3) The interlayer temperature shall not be higher than 200 ℃, to prevent the high temperature time is too long grain growth.
(4) in order to protect the surface of the arc after the arc break, should wait until the temperature of the welded spot below 300 ℃, (time in 15 ~ 60s, according to the pipe diameter from small to large and gradually extended) and then stop sending gas protection.
(5) Argon-filled protection: specific measures are as follows:
A. When welding DN greater than or equal to 450 pipes, the pipe staff wear gas masks, hand-held protective cover to protect the back of the welded molten pool.
b. For DN less than 450 pipe or fixed port welding, the overall argon protection, the inner surface of the pipe from the bevel 150-300mm at the use of soluble paper sealing, and then stuffed into a ball of soluble paper to prevent excessive air pressure inside the pipe will seal the soluble paper damage, and then filled with argon will be the air inside the pipe exhaust. Welding must be fully pre-filled with argon before welding, welding should be delayed after filling argon, so that the high temperature region fully cooled to prevent surface oxidation.
(6) Welding process filler wire should be continuously kept under the protection of argon. The welding wire should not be exposed to air immediately after arc quenching, and should be removed when the weld leaves the protection. When the welding wire is contaminated and oxidized and discolored, the contaminated part should be removed.
7) The surface of the weldment can not lead the arc or test the arc; when closing the arc, the arc crater should be filled, and the indirect ends of the layers of multi-layer welding should be staggered.
8) In addition to special requirements, each weld should be welded continuously once. If forced to interrupt for any reason, it must be inspected to determine the absence of cracks before continuing to weld.
9) When tungsten clamping occurs during the welding operation, the welding operation should be suspended, the tungsten point should be cleaned up with a grinder, and the tungsten end should be re-polished to meet the requirements before the welding operation is carried out.
The above process points ensure the normal welding of titanium tube and meet the quality requirements of titanium tube welding.
