In-situ-Analyse der Phasenumwandlungskinetik während des Schweißens
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Thomas Kannengießer
, Arne Kromm , Jens Gibmeier and Michael Rethmeier
Kurzfassung
Zugeigenspannungen, wie sie beim Schweißprozess durch inhomogene Temperaturverteilungen und Schrumpfungen hervorgerufen werden, können die Lebensdauer geschweißter Verbindungen signifikant herabsetzen. Eine neue und außerordentlich attraktive Methode, um Druckeigenspannungen bereits während des Schweißens gezielt einzustellen, gelingt mit sogenannten LTT (Low Transformation Temperature)-Legierungen. LTT-Legierungen weisen eine martensitische Phasenumwandlung bei relativ niedrigen Temperaturen auf, wobei die damit verbundene Volumenexpansion zu einer Reduktion der Schrumpfeigenspannungen bzw. Erzeugung von Druckeigenspannungen führt. Zum direkten Nachweis der Phasenumwandlungen und der damit verbundenen resultierenden Schweißeigenspannungen wurden erstmals In-situ-Schweißexperimente unter Nutzung hoch energetischer, polychromatischer Synchrotronstrahlung (Weißstrahl) realisiert, um die Umwandlungskinetik während eines realen Schweißprozesses und die daraus resultierenden Schweißeigenspannungen zu analysieren. Es wird gezeigt, dass mit LTT-Legierungen signifikante Druckeigenspannungen in der Schweißnaht erreicht werden.
Abstract
Tensile residual stresses caused by inhomogeneous temperature distributions and shrinkage during welding can substantially reduce the lifetime of welded joints. A new and extraordinarily attractive method for deliberately generating favorable compressive residual stresses already during the welding process with the help of so-called Low Transformation Temperature (LTT) alloys has proved to be successful. LTT alloys exhibit a martensitic phase transformation at relatively low temperatures involving a volume expansion that can reduce the shrinkage stresses or even create compressive residual stresses. In order to furnish direct evidence of the phase transformations and of the associated residual stresses, in-situ welding experiments using high energy polychromatic synchrotron radiation (white beam) were realized for the first time analysing the transformation kinetics during a real welding process and the resulting welding residual stresses. It is demonstrated that with the application of LTT-alloys significant compressive residual stresses are achieved in the weld.
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© 2010, Carl Hanser Verlag, München
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Articles in the same Issue
- Inhalt/Contents
- Inhalt
- Fachbeiträge/Technical Contributions
- In-situ-Analyse der Phasenumwandlungskinetik während des Schweißens
- Hochglanzoberflächen beim Spritzgießen
- The Production and Testing of Composite Friction Materials
- Effect of Nickel Addition and Porosity on Fracture Behaviour of Molybdenum Alloyed Powder Metallurgical Steel
- Surface Structural Changes of Feldspathic Ceramics Before and After Immersion in a Corrosive Medium Using Atomic Force Microscopy
- Einfluss des Warmauslagerns auf das Gefüge sowie auf die mechanischen und tribologischen Eigenschaften eines Duplexstahles
- Plasma Spray Coating of an AA 2024-T4 Al Alloy with Oxide Powders
- Microstructure and Interfacial Morphologies of Brazed NiO-YSZ/316 stainless steel using B-Ni2 brazing alloy
- Vorschau/Preview
- Vorschau