Imperfections in Inner Cavity of Row 4 Turbine Blade Caused by Metal-Core Reaction
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A. Neidel
completed training as a state-certified technical assistant for metallography and physical materials analysis at the Lette-Verein in Berlin. For the last 6 years he has been working in the laboratory of the Siemens gas turbine plant in Berlin, where the main focus of his work is damage analysis, quantitative image analysis, microstructure characterization with the field emission scanning electron microscope and X-ray fluorescence analysis.
completed a training as State Certified Technical Assistant for Metallography and Physical Material Analysis at Lette-Verein in Berlin. He has worked in the metallographic laboratory of the Siemens Gas Turbine Plant (Siemens-Gasturbinenwerk) Berlin for more than a decade. The key areas of his work are failure analysis and microstructural examinations using the field emission scanning electron microscope.
Abstract
When selecting case studies for presentation in this section Failure Analysis of Practical Metallography, the authors of this contribution asked themselves time and again what conditions actually constitute a component failure. Conventional wisdom has it that a failure occurred when a component or assembly lost its function intended by design. The authors readily admit that this is decidedly not the case for the “failure” presented in this contribution. Not only did no failure occur (the component was successfully used in engine service for the intended operating time), but the subject turbine blade did not loose its intended function by any stretch of the imagination. Why is this case study then presented here anyway? Because the evaluation and assessment of severity of indications found upon non-de structive testing of the subject turbine blade was only possible after destructive metallurgical investigation. One could jokingly concede that the blade definitely lost its function after metallographic cut-up. In any case, in the “failure case” presented in this contribution, the engineering department did not dare to release the subject turbine component for renewed engine service after refurbishment, since indications were detected that could not be properly assessed, without destroying the part; hence the subject component was not fit for engine service. The inclined reader may himself decide whether this fact makes it a component failure.
Kurzfassung
Als es darum ging, Fallbeispiele auszusuchen, die in der Rubrik Failure Analysis in der Praktischen Metallographie vorgestellt werden sollten, fragten sich die Autoren dieses Beitrags immer wieder, welche Bedingungen tatsächlich ein Bauteilversagen begründen. Nach der gängigen Meinung versagt ein Bauteil oder eine Baugruppe dann, wenn die durch die Konstruktion vorgesehene Funktion nicht mehr erfüllt wird. Die Autoren geben ohne Weiteres zu, dass dies bei dem hier vorgestellten „Versagensfall“ unzutreffend ist. Nicht nur, dass es nicht zum Bauteilversagen kam (das Bauteil wurde erfolgreich im Turbinenbetrieb über die vorgesehene Betriebszeit eingesetzt), die betreffende Turbinenschaufel hatte ihre Funktion auch beim besten Willen nicht verloren. Warum also wird dieses Fallbeispiel dennoch vorgestellt? Weil die Bewertung und Beurteilung der Schwere der bei der zerstörungsfreien Prüfung nachgewiesenen Fehler an der betreffenden Turbinenschaufel nur zerstörend im Rahmen einer metallurgischen Untersuchung möglich war. Man könnte scherzhaft einräumen, dass die Schaufel ihre Funktion auf jeden Fall verloren hatte, nachdem sie für die metallographische Präparation getrennt wurde. Jedenfalls wollte es die technische Abteilung bei dem hier vorgestellten „Versagensfall“ nicht riskieren, das betroffene Bauteil nach der Generalüberholung für den erneuten Turbinenbetrieb freizugeben, da die angezeigten Fehler ohne die Zerstörung des Bauteils nicht genau beurteilt werden konnten. Das betreffende Bauteil war daher nicht mehr für den Turbinenbetrieb geeignet. Die geneigte Leserschaft darf selbst entscheiden, ob dieser Umstand ein Bauteilversagen darstellt.
About the authors
completed training as a state-certified technical assistant for metallography and physical materials analysis at the Lette-Verein in Berlin. For the last 6 years he has been working in the laboratory of the Siemens gas turbine plant in Berlin, where the main focus of his work is damage analysis, quantitative image analysis, microstructure characterization with the field emission scanning electron microscope and X-ray fluorescence analysis.
completed a training as State Certified Technical Assistant for Metallography and Physical Material Analysis at Lette-Verein in Berlin. He has worked in the metallographic laboratory of the Siemens Gas Turbine Plant (Siemens-Gasturbinenwerk) Berlin for more than a decade. The key areas of his work are failure analysis and microstructural examinations using the field emission scanning electron microscope.
References / Literatur
[1] Neidel, A.; Fischer, B.; Cagliyan, E.: Internal Report BLN MT/2013/0376r, Berlin, June 17, 2013.Search in Google Scholar
[2] TLV 893392. Internal material specifiaction of Siemens Energy. The latest issue is applicable.Search in Google Scholar
[3] Mišković, Z.; Jovanović, M.; Gligić, M.; Lukić, B.: Microstructural investigation of IN 939 superalloy, Elsevier Volume 43, Issues 5–7, pp. 709–711, May – July 1992. DOI: 10.1016/0042-207X(92)90115-D10.1016/0042-207X(92)90115-DSearch in Google Scholar
[4] Jahangiri, M. R.; Arabi, H.; Boutorabi, S. M. R.: Development of wrought precipitation strengthened IN939 superalloy. Materials Science and Technology, Volume 28, 2012, Issue 12.10.1179/1743284712Y.0000000073Search in Google Scholar
[5] Donachie, M. J.; Donachie, S. J.: Superalloys – A Technical Guide. ASM International 2002, 2nd ed. ISBN: 0-87170-749-710.31399/asm.tb.stg2.9781627082679Search in Google Scholar
[6] Sims, C. T.: A History of Superalloy Metallurgy for Superalloy Metallurgists. Reprinted by TMS at https://www.tms.org/superalloys/10.7449/1984/Superalloys_1984_399_419.pdf, accessed July 27, 06:17 p.m. CEST.Search in Google Scholar
[7] Neidel, A. (ed.): Handbuch Metallschäden. 2nd Edition, Carl Hanser Verlag München Wien 2012. ISBN: 978-3446427754Search in Google Scholar
[8] Neidel, A. et al.: Prakt. Metallogr. 44 (2007) 9, pp. 413–429. DOI: 10.3139/147.10035410.3139/147.100354Search in Google Scholar
[9] Neidel, A. et al.: Internal Report BLN MT/2019/ 0317_final, Berlin, November 23, 2019.Search in Google Scholar
[10] Paul, U.: E-Mail communication, Mülheim, Germany, April 20, 2020.Search in Google Scholar
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- Imperfections in Inner Cavity of Row 4 Turbine Blade Caused by Metal-Core Reaction
- Picture of the Month
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Articles in the same Issue
- Contents
- Editorial
- Editorial
- Classification of fracture characteristics and fracture mechanisms using deep learning and topography data
- Combination of Digital Image Correlation (DIC) and in situ 3D-μ-CT in the analysis of the relationship between strains and porosity under creep loading
- The effect of shielding gas on weldability of the AISI 420 martensitic stainless steel
- Failure Analysis
- Imperfections in Inner Cavity of Row 4 Turbine Blade Caused by Metal-Core Reaction
- Picture of the Month
- Picture of the Month
- News
- News
- Meeting Dairy
- Meeting Diary
