Precautions for refill welding Gr12 titanium alloy pipe

General titanium tube manufacturers refill welding Gr12 titanium tube environment can not have flowing air, otherwise the same as in the welding box in the refill welding. However, special attention should be paid:
(1) the area of patch welding can not be too large, the flow of nitrogen in the process of patch welding should be larger, and can not stop in the middle of the gas;
(2) After the patch welding, should continue to pass nitrogen protection, until the region cools down;
(3) For some special castings, such as complex thin-walled castings, in order to prevent oxidation of the back of the patch welding area, you can blow argon on the back until the casting is cooled;
(4) Requirement of patch welding operators with high technical level.

In order to obtain good quality titanium tube castings for patch welding, the following points should be noted in the process of patch 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 refill welding titanium tube to prevent tungsten electrode and refill weldments 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 completely cooled down before the next layer of welding, absolutely not allowed to - weld into, in order to prevent deformation of the casting.
(4) in the filler weld is almost over, 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 castings in the box for a period of time before opening the box to remove the castings, in order to prevent the rapid cooling of the castings weld zone cracks or deformation; the length of the cooling time depends on the wall thickness of the castings, 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 patch welding should not exceed the provisions of the relevant technical documents.