Image analysis of microscopic crack patterns applied to thermal fatigue heat-checking of high temperature tool steels

Sabine Le Roux (1) , Farid Medjedoub (1) , Gilles Dour (1) , Farhad Rezai-Aria (1)

1 ICA - Institut Clément Ader

Surface cracking or heat-checking is investigated at a microscopic scale on a hot work tool steel (X38CrMoV5) tested under thermal fatigue. Thermal fatigue tests are periodically interrupted to observe the surface of the specimens by scanning electron microscopy (SEM). A non destructive and semiautomatic method is developed to assess and evaluate the two-dimensional crack pattern initiated on the oxide scale layer formed on the specimen surface. The crack pattern is characterized by image analysis in terms of density, morphological and topological features. This technique allows to determine the number of cycles to initiate the microscopic heat-checking and to follow its evolution.

Mots clés: Image analysis; Scanning electron microscopy; Thermal fatigue; Crack pattern; Hot work tool steel; Oxidation

Domaines: Mécanique des matériaux [physics.class-ph]

Sabine Le Roux, Farid Medjedoub, Gilles Dour, Farhad Rezai-Aria. Image analysis of microscopic crack patterns applied to thermal fatigue heat-checking of high temperature tool steels. Micron, 2013, 44, pp.347-358. ⟨10.1016/j.micron.2012.08.007⟩. ⟨hal-01687308⟩