Turbine Shroud Cracking Investigation and Repair
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Outer shroud segments fabricated from a cast 310 stainless steel were found to have cracked following extended service. Several of these cracked shrouds were sent to the GE-Poland Materials Laboratory for metallurgical investigation with a view to determine the cause of cracking. Detailed investigation revealed cracking to be associated with a sigma phase, a brittle TCP intermetallic, which had developed over time during engine operation. Initial attempts to weld repair the cracks proved unsuccessful as cracks were discovered both during and after the weld repair procedure. A new weld repair procedure incorporating a pre-weld solution annealing heat treatment to remove the sigma phase before welding was successfully developed, thus alleviating the cracking concern.
KeywordsSigma phase Turbine Shroud 310 stainless steel Weld repair
The authors would like to acknowledge to Dorota Szczesniak for aiding in publishing this article.
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