Cost effective repair of gas turbine components are important from an economic and safety point of view. Consequently, if expensive service-stressed parts can be repaired by welding and/or brazing, considerable cost savings can accrue. Hot end turbines components are made of superalloys which often present a challenge to the repair engineer as they are difficult to weld, especially the high Al+Ti containing alloys (> 1/2 wt.% Al+Ti). In addition, exposure to high temperatures causes them to be heavily precipitated with carbides and other phases, and often have microstructures that are significantly different than from the one they had when they entered into service, which reduces their ductility. As a result the repair welds become even more susceptible to cracking. Minor elements, such as B and S, also influence the repair and weldability through grain boundary segregation. In this communication a survey is made of the various repair schemes available in terms of wrought, polycrystalline cast and Directionally Solidified and Single Crystal Alloys.
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