3D characterization of trans- and inter-lamellar fatigue crack in (α+β) Ti alloy

• Published in: Materials characterization Vol. 98; pp. 130 - 139
• Main Authors: Babout, Laurent, Jopek, Łukasz, Preuss, Michael
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.12.2014; Elsevier
• Subjects: Applied sciences; Boundaries; COMPUTERIZED TOMOGRAPHY; CRACK PROPAGATION; CRACKS; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; FATIGUE; Fatigue failure; GRAIN BOUNDARIES; IMAGE PROCESSING; LAMELLAE; Lamellar microstructure; MATERIALS SCIENCE; MATERIALS TESTING; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Microstructure; ORIENTATION; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Short fatigue crack; SLIP; Solidification; Strategy; Three dimensional; THREE-DIMENSIONAL LATTICES; Ti alloy; TITANIUM ALLOYS; Titanium base alloys; X RADIATION; X-ray microtomography; Image processing; Ti alloy; Lamellar microstructure; X-ray microtomography; Short fatigue crack; Short crack; Lamellar structure; Mechanical properties; Fatigue; Microstructure; Fatigue cracks
• ISSN: 1044-5803; 1873-4189
• DOI: 10.1016/j.matchar.2014.10.017

This paper presents a three dimensional image processing strategy that has been developed to quantitatively analyze and correlate the path of a fatigue crack with the lamellar microstructure found in Ti-6246. The analysis is carried out on X-ray microtomography images acquired in situ during uniaxial fatigue testing. The crack, the primary β-grain boundaries and the α lamellae have been segmented separately and merged for the first time to allow a better characterization and understanding of their mutual interaction. This has particularly emphasized the role of translamellar crack growth at a very high propagation angle with regard to the lamellar orientation, supporting the central role of colonies favorably oriented for basal 〈a〉 slip to guide the crack in the fully lamellar microstructure of Ti alloy. •3D tomography images reveal strong short fatigue crack interaction with α lamellae.•Proposed 3D image processing methodology makes their segmentation possible.•Crack-lamellae orientation maps show prevalence of translamellar cracking.•Angle study comforts the influence of basal/prismatic slip on crack path.