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Title: Experimental study of crack initiation and propagation in high- and gigacycle fatigue in titanium alloys

Fatigue (high- and gigacycle) crack initiation and its propagation in titanium alloys with coarse and fine grain structure are studied by fractography analysis of fracture surface. Fractured specimens were analyzed by interferometer microscope and SEM to improve methods of monitoring of damage accumulation during fatigue test and to verify the models for fatigue crack kinetics. Fatigue strength was estimated for high cycle fatigue regime using the Luong method [1] by “in-situ” infrared scanning of the sample surface for the step-wise loading history for different grain size metals. Fine grain alloys demonstrated higher fatigue resistance for both high cycle fatigue and gigacycle fatigue regimes. Fracture surface analysis for plane and cylindrical samples was carried out using optical and electronic microscopy method. High resolution profilometry (interferometer-profiler New View 5010) data of fracture surface roughness allowed us to estimate scale invariance (the Hurst exponent) and to establish the existence of two characteristic areas of damage localization (different values of the Hurst exponent). Area 1 with diameter ∼300 μm has the pronounced roughness and is associated with damage localization hotspot. Area 2 shows less amplitude roughness, occupies the rest fracture surface and considered as the trace of the fatigue crack path corresponding to themore » Paris kinetics.« less
Authors:
; ;  [1]
  1. Institute of Continuous Media Mechanics UrB RAS, Perm, 614013 (Russian Federation)
Publication Date:
OSTI Identifier:
22390444
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1623; Journal Issue: 1; Conference: International Conference on Physical Mesomechanics of Multilevel Systems 2014, Tomsk (Russian Federation), 3-5 Sep 2014; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; BUILDUP; CRACK PROPAGATION; CRACKS; DAMAGE; FATIGUE; FRACTOGRAPHY; FRACTURES; GRAIN SIZE; LOADING; MONITORING; RESOLUTION; ROUGHNESS; SCALE INVARIANCE; SCANNING ELECTRON MICROSCOPY; SURFACES; TITANIUM ALLOYS