Generally, the environment for repairing titanium pipes by titanium pipe manufacturers cannot have flowing air, and other aspects are the same as repair welding in the welding box. But special attention should be paid to:
(1) The area of repair welding should not be too large, the flow of nitrogen during repair welding should be larger, and the gas should not be stopped in the middle;
(2) After repair welding, nitrogen protection should be continued until the area cools down;
(3) For some special castings, such as complex thin-walled castings, in order to prevent oxidation of the backside of the repair welding area, argon gas can be blown to the backside until the castings are cooled;
(4) The repair welding operator is required to have a high technical level.
In order to obtain titanium tube castings with good repair welding quality, the following points should be paid attention to in the repair welding process:
(1) The surface of the casting for repair welding must be cleaned and dried, and the casting is not allowed to be directly touched by hand before being loaded into the welding box.
(2) Strictly prevent the short circuit between the tungsten electrode and the repair welding piece during the process of repairing the titanium tube, which will cause the tungsten electrode to break and cause tungsten inclusions in the solder joints.
(3) When the area and depth of the repair welding area are relatively large, it should be welded in multiple remote layers, and the welding of the next layer can only be carried out after the previous layer of welding layer is completely cooled. To prevent casting deformation.
(4) At the end of repair welding, the current should be gradually reduced to reduce the melting zone. Therefore, it is recommended to use pulsed current to prevent sharp arc breaking, resulting in cracks.
(5) After the repair welding, the casting should be allowed to cool in the box for a period of time before taking out the casting to prevent cracks or deformation in the welding area of the casting caused by rapid cooling; the length of cooling time depends on the wall thickness of the casting, usually 15-30mm .
(6) After repair welding of titanium tube castings, it should be annealed or hot isostatic pressing in time, and it should not be left for too long, usually no more than 5 days.
(7) The number of repair welding shall not exceed the provisions of the relevant technical documents.