Welding repairing is widely used process for repairing investment castings.
First step, we have to fix the place, size and the types of the defects. Then get the weld equipment ready.
Second step is to dig certain areas around the defects. And Then, grind or machine the suitable welding grooves.
Third step is to choose suitable weld materials. Usually the welding material is the same or similar as the castings. But for some special casting materials, such as the manganese steel(usually used weld material is SS309 steel), machined surface(weld material should be with lower stress), we have to choose the higher quality welding materials to ensure the weld quality.
Fourth step is to choose the right welding speed and welding types according to the size, depth and types of the defects. The final welds should be raised from the casting surface. Then machined smoothly by grinding or machining.
To control the quality of the castings, it's much better to do the NDT inspection, such as PT or UT on the welding surface to ensure that there's no weld cracks or undercut defects.