Solidification Cracking in Manually TIG-Brazed T/C Installations of Novel AM Gas Turbine Burner Component

Serial fabrication of novel selective laser melted (SLM) heavy-duty gas turbine burner parts was established. This is an additive manufacturing (AM) process. Thermocouples (T/C) are manually tungsten inert gas (TIG) brazed to these components. After fabrication, they exhibited severe cracking within the brazed T/C joints and had to be scrapped. A laboratory order for a destructive metallographic investigation was placed by the client with the aim of determining the metallurgical cause of the cracking. The crack path is interdendritic. The crack propagated within the braze metal only. The crack morphology is consistent with solidification cracking (SC), a hot cracking mechanism. No evidence of liquid metal embrittlement, or LME, was found.