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Experimental Investigation and Numerical Simulation of High Temperature Fatigue of Seam Welds

Langschwager, Kay and Bosch, Alexander and Lang, Eliane and Scholz, Alfred and Vormwald, Michael and Oechsner, Matthias (2014):
Experimental Investigation and Numerical Simulation of High Temperature Fatigue of Seam Welds.
In: Proceedings of the 4th Symposium on Structural Durability in Darmstadt, SoSDiD; May 14th-15th, 2014, Darmstadt, Germany; MARITIM Konferenzhotel. Editors: J. Baumgartner, T. Melz. Stuttgart: Fraunhofer Verl., 2014, S. 83 – 108. ISBN 978-3-8396-0734-3, [Book Section]

Abstract

Austenitic stainless steel of type X6CrNiNb18-10 (1.4550) is a widely used material in piping and components of nuclear power plants. The fatigue behavior of these components is often operationally determined by thermomechanical strains and corresponding stresses. Welded structures lead to complex stresses in the component and potential fatigue lifetime reductions. Various geometries and microstructural inhomogeneities in welded structures represent the main factors of influence. Nevertheless, clear identification and quantification of various factors of influence are issues still to be resolved. Within the framework of an ongoing research project, the experimental investigation comprises uniaxial and biaxial fatigue experiments on welded joints which cover temperatures from 25°C to 350°C. Furthermore, a key issue deals with the thermomechanical fatigue behavior of machined and unmachined butt welded joints. A special focus is set on typical low cycle fatigue (LCF) tests in order to explain the behavior of the base material and the weld material to identify the influence of microstructural inhomogeneities. In addition, specimens manufactured directly from the pipe components are tested to examine the influence of the butt weld seam geometry. For a better understanding of the local strain effects, optical strain field measurements (OSFM) are conducted and used to validate numerical simulation. The finite element method (FEM) is utilized to expand the parameter space and identify the main parameters. The results gained (experimental and numerical) show that fatigue failure occurs either in the base metal in the vicinity of the welded zone or in the top layer of the weld, depending on the loading conditions. This knowledge is used to develop an approach to model the fatigue lifetime.

Item Type: Book Section
Erschienen: 2014
Creators: Langschwager, Kay and Bosch, Alexander and Lang, Eliane and Scholz, Alfred and Vormwald, Michael and Oechsner, Matthias
Title: Experimental Investigation and Numerical Simulation of High Temperature Fatigue of Seam Welds
Language: English
Abstract:

Austenitic stainless steel of type X6CrNiNb18-10 (1.4550) is a widely used material in piping and components of nuclear power plants. The fatigue behavior of these components is often operationally determined by thermomechanical strains and corresponding stresses. Welded structures lead to complex stresses in the component and potential fatigue lifetime reductions. Various geometries and microstructural inhomogeneities in welded structures represent the main factors of influence. Nevertheless, clear identification and quantification of various factors of influence are issues still to be resolved. Within the framework of an ongoing research project, the experimental investigation comprises uniaxial and biaxial fatigue experiments on welded joints which cover temperatures from 25°C to 350°C. Furthermore, a key issue deals with the thermomechanical fatigue behavior of machined and unmachined butt welded joints. A special focus is set on typical low cycle fatigue (LCF) tests in order to explain the behavior of the base material and the weld material to identify the influence of microstructural inhomogeneities. In addition, specimens manufactured directly from the pipe components are tested to examine the influence of the butt weld seam geometry. For a better understanding of the local strain effects, optical strain field measurements (OSFM) are conducted and used to validate numerical simulation. The finite element method (FEM) is utilized to expand the parameter space and identify the main parameters. The results gained (experimental and numerical) show that fatigue failure occurs either in the base metal in the vicinity of the welded zone or in the top layer of the weld, depending on the loading conditions. This knowledge is used to develop an approach to model the fatigue lifetime.

Title of Book: Proceedings of the 4th Symposium on Structural Durability in Darmstadt, SoSDiD; May 14th-15th, 2014, Darmstadt, Germany; MARITIM Konferenzhotel. Editors: J. Baumgartner, T. Melz. Stuttgart: Fraunhofer Verl., 2014, S. 83 – 108. ISBN 978-3-8396-0734-3
Divisions: 13 Department of Civil and Environmental Engineering Sciences > Institute of Steel Constructions and Material Mechanics
13 Department of Civil and Environmental Engineering Sciences > Institute of Steel Constructions and Material Mechanics > Fachgebiet Werkstoffmechanik
16 Department of Mechanical Engineering
16 Department of Mechanical Engineering > Center for Engineering Materials, State Materials Testing Institute Darmstadt (MPA) Chair and Institute for Materials Technology (IfW)
13 Department of Civil and Environmental Engineering Sciences
Date Deposited: 23 Apr 2015 12:14
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