Influence of high-pressure gaseous hydrogen on the low-cycle fatigue and fatigue crack growth properties of a cast titanium alloy
Journal article, 2014

In the present study, the effect of gaseous hydrogen on the fatigue properties of a commonly used aerospace titanium alloy (Ti–6Al–4V) was studied. The low-cycle fatigue and fatigue crack growth properties were investigated at room temperature in ambient air and 15 MPa gaseous hydrogen. Results showed that the low-cycle fatigue life was significantly reduced in hydrogen, and the detrimental effect was larger at higher strain amplitudes. The fatigue crack growth rate in hydrogen remained unaffected below a critical stress intensity ΔKn E 17 MPa√m, while beyond this value, the fatigue crack growth rate fluctuated and increased with increasing ΔK. Fractography analysis clearly showed that gaseous hydrogen mainly affected the fatigue crack growth rate. On the fracture surfaces, striations were noted over the entire crack growth region in air, whereas in hydrogen striations were noted at stress intensities lower than ΔKn. Above ΔKn, secondary cracks and brittle flat surfaces with features similar to crack arrest marks were mostly observed in hydrogen. Microstructural analysis along the crack growth direction showed that the crack followed a transgranular path in air, i.e. through α colonies. In hydrogen, the crack also grew along the prior β grain boundaries and at α/β interface within the α colonies. Thereby, the detrimental effect of hydrogen in cast titanium alloy was attributed to a change in the fracture process during crack propagation.

Fracture

Fatigue

Hydrogen embrittlement

Titanium alloys

Electron microscopy

Mechanical characterisation

Author

Raghuveer Gaddam

Luleå University of Technology

Sandvik

Magnus Hörnqvist Colliander

Chalmers, Applied Physics, Materials Microstructure

Marta-Lena Antti

Luleå University of Technology

Robert Pederson

Luleå University of Technology

Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing

0921-5093 (ISSN)

Vol. 612 354-362

Subject Categories

Mechanical Engineering

Materials Engineering

Other Materials Engineering

Areas of Advance

Materials Science

DOI

10.1016/j.msea.2014.06.060

More information

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9/8/2022 8