The fatigue crack growth characteristics of an Fe20Cr20Ni20Mn20Co high-entropy alloy (HEA) were investigated by ΔK increasing compact tension test in comparison with SUS316L. The fatigue crack growth rate of the HEA was lower than that of the SUS316L. The predominant crack growth path was the grain interior for both alloys. A difference was observed in the crack roughness; i.e., the fatigue crack growth path of the HEA was more distinctly deflected than that of the SUS316L. This indicates that roughnessinduced crack closure is a key factor reducing the crack growth rate of the HEA. Another key factor is the noncrystallographic transgranular crack growth mechanism. The SUS316L exhibited crack growth via crack blunting/re-sharpening, while the HEA exhibited transgranular crack growth associated with dislocation substructure alignment.

Synopsis : FatiguecrackgrowthcharacteristicsofanFe20Cr20Ni20Mn20Cohighentropyalloy(HEA)wereinvestigatedbyΔK increasing compact tension test in comparison with a SUS316L. Fatigue crack growth rate of the HEA was lower than that of the SUS316L. The predominant crack growth path was grain interior for both alloys. A difference was found to be in the crack roughness, namely, the fatigue crack growth path oftheHEAwasmoredistinctlydeflectedcomparedwiththatoftheSUS316L.Thisfactindicatesthatroughness-inducedcrackclosureisa key factor decreasing the crack growth rate of the HEA. Another key is a non-crystallographic transgranular crack growth mechanism. The SUS316L shows crack growth via crack blunting/re-sharpening, while the HEA shows transgranular crack growth associated with dislocation substructure alignment.

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