Metallographic characterization of axial shims surface damaged upon assembly
-
M. Giller
Madeleine Giller Apprenticeship as a materials testing technician at the welding institute SLV Berlin-Brandenburg. After that, she studied materials science at the Berlin Institute of Technology. She graduated with a masters degree in materials science in 2012. Since November 2012 employment as engineer at the Metallography Laboratory of the Siemens Gas Turbine Works in Berlin. She has been appointed laboratory manager within the Berlin Testing Center of the Large Gas Turbine Engineering Group in 2014. Her main fields of expertise comprise failure analysis and microstructural investigations using the field emission scanning electron microscope.Tobias Gädicke was born in 1986 and joined the Siemens Energy Sector in 2005 as apprentice in the Berlin Gas Turbine Works. As materials testing technician, his main field of expertise is metallo-graphic target preparation of laser-drilled holes in turbine blading. Also, he is expert in the field of portable metallography by means of the replica technique with both putty and replica foils which he regularly applies to microstructural analyses of large gas turbine casings made of ductile iron and steel castings. He is a lecturer in the DGM seminar on portable metallography. Metallurgical failure analysis of gas turbine engine hot gas path components are another field of expertise of his.
Abstract
Surface damage to axial shims was reported from the final assembly department of an original equipment manufacturer (OEM) of large gas turbine engines. The damage reportedly occurred upon casing assembly, namely during the “wedding” of the compressor exhaust diffuser with the outer casing. The subject parts were new and never saw any engine service. The subject shims were made of a low-alloy quenched and tempered steel. Their surface hardness was considered too low for this particular application. To rectify the problem, the shims received a physical vapor deposition (PVD) coating using CrN. It was determined that the metallurgical root cause of the surface damage was what is called the eggshell effect. The very hard PVD coating could not be supported by the relatively soft core of the low-alloy steel, causing cracking of the coating and subsequent galling of the substrate when the two heavy casings to be mated in final assembly touched each other hard.
Kurzfassung
Die Endmontage eines OEM-Herstellers von Großgasturbinen berichtete von Oberflächenschäden an Axialbeilagen. Die Schäden entstanden den Berichten zufolge bei der Montage des Gehäuses, konkret bei der Verbindung des Abgasdiffusors des Verdichters mit dem Außengehäuse. Die entsprechenden Teile waren neu und noch nie im Turbinenbetrieb. Die Beilagen bestanden aus niedriglegiertem, vergütetem Stahl. Die Härte Ihrer Oberfläche erwies sich für diese spezielle Anwendung als zu gering. Zur Behebung dieses Problems wurden die Beilagen mit CrN PVD beschichtet. Als metallurgische Grundursache des Oberflächenschadens wurde der sogenannte Eierschaleneffekt ermittelt. Vom relativ weichen Kern des niedriglegierten Stahls konnte die sehr harte PVD-Beschichtung nicht gestützt werden. In der Folge bildeten sich Risse in der Beschichtung und es kam anschließend zu einer Kaltverschweißung des Substrats, als die beiden schweren Gehäuse, die bei der Endmontage miteinander verbunden werden sollten, hart aufeinander trafen.
About the authors
Madeleine Giller Apprenticeship as a materials testing technician at the welding institute SLV Berlin-Brandenburg. After that, she studied materials science at the Berlin Institute of Technology. She graduated with a masters degree in materials science in 2012. Since November 2012 employment as engineer at the Metallography Laboratory of the Siemens Gas Turbine Works in Berlin. She has been appointed laboratory manager within the Berlin Testing Center of the Large Gas Turbine Engineering Group in 2014. Her main fields of expertise comprise failure analysis and microstructural investigations using the field emission scanning electron microscope.
Tobias Gädicke was born in 1986 and joined the Siemens Energy Sector in 2005 as apprentice in the Berlin Gas Turbine Works. As materials testing technician, his main field of expertise is metallo-graphic target preparation of laser-drilled holes in turbine blading. Also, he is expert in the field of portable metallography by means of the replica technique with both putty and replica foils which he regularly applies to microstructural analyses of large gas turbine casings made of ductile iron and steel castings. He is a lecturer in the DGM seminar on portable metallography. Metallurgical failure analysis of gas turbine engine hot gas path components are another field of expertise of his.
References / Literatur
[1] Neidel, A. et al.: Metallographic Characterization of Axial CED/Maxi Shims Surface Damaged Upon Assembly. Internal report BLN MT/2024/0435, Berlin, November 15, 2024.Search in Google Scholar
[2] Neidel, A. et al.: Intergranular Corrosion in Retaining Rings Made of X39CrMo17-1 and X39Cr13. Pract. Metallogr. 51 (2014) 6, pp. 463–474. DOI:10.3139/147.11024810.3139/147.110248Search in Google Scholar
[3] Neidel, A.; Gädicke, T.: Intergranular Corrosion in X39CrMo17-1 – A Review. Pract. Metal-logr. 60 (2023) 9, pp. 594–615. DOI:10.1515/pm-2023-005010.1515/pm-2023-0050Search in Google Scholar
[4] ASM Handbook, Vol. 11: Failure Analysis and Prevention, Sixth printing, American Society for Metals, Handbook Committee, 1998.Search in Google Scholar
[5] Seume, J.; Lechner, C. (Ed.): Stationäre Gasturbinen, Springer-Verlag, Berlin, Heidelberg, Deutschland, 2003.10.1007/978-3-662-10016-5Search in Google Scholar
[6] Grosch, J.: Schadenskunde im Maschinenbau. 4. Auflage, Expert Verlag, 2004.Search in Google Scholar
© 2025 Walter de Gruyter GmbH, Berlin/Boston, Germany
Articles in the same Issue
- Contents
- Editorial
- Editorial
- Practical application of an automated 3D metallography system for the reconstruction and microstructural analysis of porosity in a sintered steel
- A quasi-in situ EBSD study of the mechanism of cubic texture formation in a large strain Ni5W alloy substrates
- Failure Analysis
- Metallographic characterization of axial shims surface damaged upon assembly
- Picture of the Month
- Picture of the Month
- News
- News
- Meeting Diary
- Meeting Diary
Articles in the same Issue
- Contents
- Editorial
- Editorial
- Practical application of an automated 3D metallography system for the reconstruction and microstructural analysis of porosity in a sintered steel
- A quasi-in situ EBSD study of the mechanism of cubic texture formation in a large strain Ni5W alloy substrates
- Failure Analysis
- Metallographic characterization of axial shims surface damaged upon assembly
- Picture of the Month
- Picture of the Month
- News
- News
- Meeting Diary
- Meeting Diary
