Experimental investigation of crack initiation and propagation in high- and gigacycle fatigue in titanium alloys by study of morphology of fracture
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 electronic microscope to improve methods of monito...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Gruppo Italiano Frattura
2016-01-01
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| Series: | Fracture and Structural Integrity |
| Subjects: | |
| Online Access: | http://www.gruppofrattura.it/pdf/rivista/numero35/numero_35_art_06.pdf |
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| Summary: | 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 electronic microscope to improve methods of monitoring of damage
accumulation during fatigue test and verify the models for fatigue crack kinetics. Fatigue strength was estimated
for high cycle fatigue (HCF) 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 HCF and gigacycle fatigue regimes. Fracture surface analysis for cylindrical samples
was carried out using optical and electronic microscopy method. High resolution profilometry (interferometerprofiler
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 the Paris kinetics |
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| ISSN: | 1971-8993 1971-8993 |