Dwell effects on low cycle fatigue behaviour of diffusion coated nickel base superalloy IN 713LC at temperature of 800° C

0444732 - ÚFM 2016 RIV DE eng A - Abstract
Šulák, Ivo - Obrtlík, Karel - Hutařová, S. - Juliš, M. - Podrábský, T. - Čelko, L.
Dwell effects on low cycle fatigue behaviour of diffusion coated nickel base superalloy IN 713LC at temperature of 800° C.
Book of Abstracts. Karlsruhe: Karlsruhe Institute of Technology, 2015 - (Eifler, D.; Heilmaier, M.; Kraft, O.; Löhe, D.). s. 382-382
[ICM12 - International Conference on the Mechanical Behavior of Materials /12./. 10.05.2015-14.05.2015, Karlsruhe]
R&D Projects: GA MŠMT(CZ) EE2.3.20.0214; GA ČR(CZ) GA15-20991S; GA TA ČR(CZ) TA04011525
Institutional support: RVO:68081723
Keywords : High temperature * Low cycle fatigue * Dwell time * Diffusion coatings * Inconel 713LC
Subject RIV: JL - Materials Fatigue, Friction Mechanics
http://icm12.com/wp-content/uploads/2015/05/Book_of_Abstracts_ICM12.pdf

Materials used for high temperature applications in gas turbine engines are exceptional due to their resistance to mechanical and thermal loading as well as resilience against chemical attacks by high temperature oxidation. First generation Ni-base superalloy IN 713LC is the representative of cast materials used for these purposes. However, the continuously enhancing of operating temperatures severely degrades the material surface and adversely affects the strength properties. Protecting the surface and prevention of its degradation is a major goal of today and tomorrow. Diffusion coatings are used to safeguard the material from aggressive environments and to improve oxidation stability of surface. The theme of the presented paper is focused on the study of low cycle fatigue with tension dwells of cast nickel-base superalloy IN 713LC with Al-Cr difussion coating at 800 °C. Attention is paid to the microstructure observation of the substrate material and Al-Cr diffusion layer. For purpose of this work a cylindrical specimens were cut from the rods manufactured using investment castings. Low cycle fatigue tests and tests with a 10 minut tension dwells included in each cycle were conducted in strain control mode with constant total strain amplitude at 800 °C. The fatigue behaviour was assessed by cyclic hardening/softening curves, cyclic stress-strain curves, Manson-Coffin curves and Basquin curves. The substrate and the Al-Cr coating was analysed in as-received conditions and also after cyclic loading by means of optical microscopy, as well as SEM, energy dispersive spectroscopy (EDS) and Knoop microhardness in terms of coating`s thickness, morphology, composition and hardness. Microstructure of the Al-Cr layer comprises an outer and an inner diffusion layer where is dispersed a large amount of complex particles based on Cr, Mo and Nb. During the tests rafting of precipitates occurred in the substrate. The diffusion layer remained unchanged.
Permanent Link: http://hdl.handle.net/11104/0247262