In order to obtain titanium tube casting with good repair welding quality, the following points should be paid attention to during repair welding:
(1) The surface of the repaired casting must be cleaned and dried, and the casting shall not be touched directly by hand before being loaded into the welding box.
(2) During the repair welding of titanium pipe, the tungsten electrode and the repair welding parts shall be strictly prevented from short circuit, resulting in the fracture of the tungsten electrode and tungsten inclusion in the welding spot.
(3) When the area and depth of the repair welding area is relatively large, multiple layers of welding should be conducted, and the welding of the next layer can only be carried out after the previous layer is completely cooled. One-layer welding is absolutely not allowed, in order 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 pulse current to prevent sharp arc break and crack.
(5) After the completion of repair welding, the casting shall be cooled in the box for a period of time before opening the box to take out the casting, so as to prevent the cracking or deformation of the casting welding area caused by rapid cooling; The cooling time depends on the wall thickness of the casting, usually between 15 and 30mm.
(6) After repair welding of titanium tube casting, it shall be timely annealed or thermally isostatic pressed, and shall not be used 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.
