Product Code: PIC06_704

Reconditioning of Nickel Base HPT Blades and Vanes used in Aero Engines and Power Plant Gas Turbines by Combination of Direct Laser Forming, Laser Metal Deposition and Laser Drilling
Authors:
Ernst Wolfgang Kreutz, Lehrstuhl für Lasertechnik der RWTH Aachen; Aachen Germany
Ingomar Kelbassa, Fraunhofer ILT; Aachen Germany
Konrad Wissenbach, Fraunhofer ILT; Aachen Germany
Lena Trippe, Lehrstuhl für Lasertechnik der RWTH Aachen; Aachen Germany
Wilhelm Meiners, Fraunhofer ILT; Aachen Germany
Presented at PICALO 2006

Parts like HPT (High Pressure Turbine) blades and vanes with integrated cooling channels cannot be repaired. The parts are replaced by new ones. The aim is to develop and implement a reconditioning chain to avoid scrapping of the part. The reconditioning chain covers the three different Laser Applications 1. Direct Laser Forming (DLF), 2. Laser Metal Deposition (DLF) and 3. Laser Drilling (LD) which are arranged in subsequent Processing Steps. The damaged volume of the blade or vane is replaced by a fitting patch with integrated cooling channels which is generatively manufactured by DLF based on CAD data acquired by digitizing and reverse engineering in a first step. The generated patch is joined into the remaining part of the blade or vane by LMD. The non open cooling channels are opened and in case of necessity reshaped by LD in the third step. Also the cooling channels damaged or destroyed in the joint zone patch-substrate by the LMD joining process within step 2 are reworked or inserted by LD in the third step. First results achieved within basic R & D of DLF, LMD and LD of relevant Nickel Base Alloys are presented. The determined suitable process parameter windows including suitable preheating temperature ranges to achieve defect free (crack, pore and bonding defect free) DLF and LMD results as well as defect minimized (thickness of recast layer, cracks and bore hole geometry) LD results are shown. The influence of the process parameters on the results achieved by DLF, LMD and LD are discussed.