What aspects should be paid attention to when repairing titanium tubes

To obtain high-quality weld repairs on titanium tube castings, attention should be paid to the following points during the repair process:
1. The surface of the casting to be repaired must be clean and dry. The casting should not be touched directly with hands before being placed in the welding box.
2. During the titanium tube repair process, short circuits between the tungsten electrode and the repaired part should be strictly prevented to avoid tungsten inclusions in the weld.
3. When the area and depth of the repair zone are relatively large, multiple pass welding should be performed, and the previous weld layer should be fully cooled before the next layer is welded to prevent deformation of the casting.
4. As the repair nears completion, the current should be gradually decreased to narrow the melting zone. Therefore, it is recommended to use pulse current to prevent cracking caused by sudden arc breaking.
5. After the repair is completed, the casting should be allowed to cool in the box for a certain period of time before removing it from the box to prevent cracking or deformation of the soldering area. The cooling time depends on the wall thickness of the casting, usually between 15-30mm.
6. After repair welding of titanium tube castings, it should be annealed or hot-isostatically pressed in a timely manner, and should not be left idle for too long, usually not exceeding 5 days.
7. The number of repair welding should not exceed the regulations specified in the relevant technical documents.
In addition, when repairing titanium tubes, the environment should not have flowing air, and other aspects should be similar to repair welding in the welding box. However, the following points should be particularly noted:
1. The repair area should not be too large, the flow rate of nitrogen during repair should be higher, and nitrogen should not be stopped in the middle of the process.
2. After the repair welding is completed, nitrogen protection should be continued until the repair area is cooled.
3. For some special castings, such as complex thin-walled castings, to prevent oxidation on the back of the repair area, argon can be blown on the back until the casting is cooled.
4. It is required that the repair operator has a higher level of technical expertise.