But it should be noted:
1. The repair welding area should not be too large, the flow of ammonia gas should be larger during the repair welding process, and the gas should not be stopped in the middle;
2. After the repair welding is completed, ammonia gas protection should be continued until the area cools down:
3. For some specific castings, such as complex thin-walled castings, in order to avoid oxidation of the back side of the repair welding area, xenon gas can be blown onto the back side until the casting cools;
4. Repair welding operators are required to have a high technical level.
In order to obtain titanium tube castings with good repair welding quality, the following points should be noted during the repair welding process:
1. The surface of the castings for repair welding must be clean and dry. The castings are not allowed to be touched directly by hand before being put into the welding box.
2. During the repair welding of titanium pipes and titanium coils, be careful not to short-circuit the tungsten electrode and the repair welding parts, which may 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, welding should be carried out in multiple remote layers, and the next layer must be welded after the previous layer has cooled down. It is not allowed to be welded in one go to avoid deformation of the casting.
4. At the end of repair welding, the current should be gradually reduced to narrow the melting zone. Therefore, it is recommended to use pulse current to avoid accelerating arc breaking and causing cracks.
5. After the repair welding is completed, the casting should be allowed to cool in the box for a period of time before unpacking the casting to avoid cracks or deformation in the welding area of the casting due to rapid cooling; the length of cooling time depends on the wall thickness of the casting, usually 15-30mm.
6. After repair welding of titanium pipes and titanium coil castings, they should be annealed or hot isostatically pressed in time. They should not be left alone for too long, usually not more than 5 days.
