The Role of Extrusions and Intrusions in the Initiation and Intergranular Growth of Fatigue Cracks

0585637 - ÚFM 2025 RIV DE eng J - Journal Article
Polák, Jaroslav - Babinský, Tomáš - Vražina, Tomáš - Kruml, Tomáš
The Role of Extrusions and Intrusions in the Initiation and Intergranular Growth of Fatigue Cracks.
Advanced Engineering Materials. early access (2024), č. článku 2400313. ISSN 1438-1656. E-ISSN 1527-2648
Institutional support: RVO:68081723
Keywords : persistent slip bands * stage-i propagation * high-strain fatigue * mechanisms * copper * model * micromechanisms * nucleation * fracture * metals * crack growths * extrusions * fatigues * intergranular facets * intrusions
OECD category: Materials engineering
Impact factor: 3.6, year: 2022
Method of publishing: Limited access
https://onlinelibrary.wiley.com/doi/10.1002/adem.202400313

The role of extrusions and intrusions in the initiation and growth of intergranular fatigue cracks is studied by performing strain-controlled fatigue experiments on polycrystalline copper and by analyzing the development of intergranular crack initiation and resulting fracture surfaces. Fatigue cracks initiate either in the persistent slipbands within a grain or on the grain boundaries. The grain boundary initiation mechanism is due to the production of extrusions and intrusions on the grain boundaries that decrease the grain boundary cohesion forming submicroscopic crack nuclei. The alternating extrusions and intrusions are found also on the grain boundary facets of the fracture surface of a growing fatigue crack. Up to three slip systems are identified on the facets of cracked grain boundaries. Their form and height are found using scanning electron microscope observations and focused ion beam sectioning. A mechanism similar to intergranular grain boundary crack initiation is considered to explain the formation of grain boundary facets. A novel mechanism of intergranular fatigue crack growth is proposed based on the damaging effect of the extrusions and intrusions produced in the cyclic plastic zone of the growing fatigue crack.
Permanent Link: https://hdl.handle.net/11104/0353320