Investigator: Ing. Martin Petrenec, Ph.D.
Number of Project: 106/05/P521
Agency: Czech Science Foundation
Duration: 01. 01. 2005 - 31. 12. 2007

The project is aimed at mapping dislocation structures in Inconel type superalloys cyclically deformed at high temperatures that are used for design of wheels of combustion turbines. The spatial arrangement of dislocations in individual grains will be documented with the aim to obtain information on the dislocation structures corresponding to localisation of the cyclic plastic strain where fatigue cracks initiate. Transmission electron microscope and scanning electron microscope techniques will be adopted to study three types of cast superalloys cyclically deformed at high temperatures and at room temperature. Specimens will be cycled in a computer controlled electrohydraulic testing machine strain control. The technique of oriented foils will be applied, which allows determining the spatial dislocation arrangement and orientation dependence in individual grains. Project aims to widen the present knowledge on the mechanism of fatigue damage related to the initiation of fatigue cracks emerging from persistent slip bands crossing matrix or starting from the casting defects. The results will deepen our knowledge of these important structural materials used preferably in aircraft and power generation industries. The understanding of mechanisms of the service damage will contribute to the application of these materials and in evaluation of fatigue life of the structural members.

PETRENEC M, OBRTLÍK K, POLÁK J, MAN J, HRBÁČEK K: Fatigue behaviour of cast nickel based superalloy INCONEL 792-5A at room temperature. Materials Engineering 12 (2005) 21–24 (in Czech).

PETRENEC M, OBRTLÍK K, POLÁK J, MAN J: Dislocation structures in nickel based superalloy inconel 792-5A fatigued at room temperature and 700 °C. Mater. Sci. Forum 567–568 (2008) 429–432.