In order to obtain good quality titanium pipe castings, the following points should be noted in the process of refill welding:
(1) the surface of the patch welding castings must be clean and dry, the castings are not allowed to be directly touched by hand before loading into the welding box.
(2) In the process of replacing the titanium tube to prevent the tungsten electrode and replenishment of short-circuit, resulting in tungsten electrode fracture, resulting in tungsten inclusions in the welded joints.
(3) When the area and depth of the patch welding area is relatively large, should be divided into several times far layer welding, and to wait until the previous layer of welding layer is completely cooled before the next layer of welding, do not allow - times welded, in order to prevent deformation of the casting.
(4) In the filler weld is almost finished, should gradually reduce the current, reduce the melting zone. Therefore, it is recommended to use pulsed current to prevent sharp arc breakage, resulting in cracks.
(5) After the end of refill welding should be allowed to cool the casting in the box for a period of time before opening the box to remove the casting, in order to prevent the rapid cooling of the casting weld zone cracks or deformation; the length of the cooling time depends on the wall thickness of the casting, usually in the 15-30mm.
(6) titanium tube castings after replenishment welding, should be promptly annealed or hot isostatic pressure, should not be shelved for too long, usually no more than 5 days.
(7) The number of times of refill welding should not exceed the provisions of the relevant technical documents.
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