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Ferrite in the HAZ of Dissimilar Temperature Probe Welds

Ferrit in der WEZ artungleicher Temperatursondenschweißungen
  • A. Neidel , M. Giller

    Madeleine Giller Apprenticeship as a materials testing technician at the welding institute SLV BerlinBrandenburg. 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.

    and S. Riesenbeck

    Susanne Riesenbeck joined the Gas Turbine Plant of Siemens’ Energy Sector in 1984 and first underwent vocational training there. As a materials testing technician, one of the first fields of her professional endevours was steam turbine service, namely remaining lifetime assessment by means of the replica technique. She is a metallographer and one of the principal failure analysts in the materials testing laboratory. Her main fields of expertise comprise microstructural analyses of steel and iron castings.

From the journal Practical Metallography

Abstract

Protector tubes for temperature sensors were welded onto experimental gas turbine compressor blades. While the blades were made of a high alloy hard-martensitic stainless chromium steel, a high alloy metastable austenitic stainless steel was used for the tiny protector tubes. The dissimilar weld joint was applied using manual GTAW. A large amount of blocky delta ferrite formed in the HAZ immediately adjacent to the fusion line, on the side of the martensitic steel. Delta ferrite in such dissimilar welds might detrimentally affect the mechanical properties of the weld joint. It was therefore recommended not to use the affected experimental blades in test engine service. Even though no failure occurred in this case, one was prevented by declaring the subject instrumented parts unfit for test engine service.

Kurzfassung

Auf für Versuche vorgesehene Gasturbinenverdichterschaufeln wurden Schutzröhrchen für Temperatursensoren aufgeschweißt. Während die Schaufeln aus einem rostfreien hochlegierten hartmartensitischem Chromstahl hergestellt wurden, wurde zur Herstellung der winzigen Schutzröhrchen ein rostfreier hochlegierter metastabiler austenitischer Stahl verwendet. Die Mischschweißverbindung wurde durch manuelles Wolfram-Inertgas-Lichtbogenschweißen, GTAW, ausgeführt. In der Wärmeeinflusszone, WEZ, bildete sich unmittelbar angrenzend an die Schmelzlinie auf der Seite des martensitischen Stahls eine große Menge an blockartigem Deltaferrit. In solchen Mischschweißnähten kann sich Deltaferrit negativ auf die mechanischen Eigenschaften der Schweißnaht auswirken. Daher wurde empfohlen, die entsprechenden Versuchsschaufeln nicht für den Testbetrieb der Turbinen einzusetzen. In diesem Fall ist es zwar nicht zum Versagen gekommen, einem Versagen wurde allerdings dadurch vorgebeugt, dass die entsprechenden instrumentierten Teile als für den Testbetrieb der Turbine untauglich erklärt wurden.

About the authors

M. Giller

Madeleine Giller Apprenticeship as a materials testing technician at the welding institute SLV BerlinBrandenburg. 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.

S. Riesenbeck

Susanne Riesenbeck joined the Gas Turbine Plant of Siemens’ Energy Sector in 1984 and first underwent vocational training there. As a materials testing technician, one of the first fields of her professional endevours was steam turbine service, namely remaining lifetime assessment by means of the replica technique. She is a metallographer and one of the principal failure analysts in the materials testing laboratory. Her main fields of expertise comprise microstructural analyses of steel and iron castings.

References / Literatur

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Received: 2020-05-03
Accepted: 2020-05-29
Published Online: 2022-12-18
Published in Print: 2022-12-30

© 2023 Walter de Gruyter GmbH, Berlin/Boston, Germany

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