Damage propagation mechanism in low-cycle creep fatigue of Cu–Cr–Zr alloy

• The rupture life in the creep–fatigue test was much shorter than that in the simple creep or fatigue.
• Creep-voids were generated and grew during stress-holding period, and fatigue crack propagated along grain boundaries during strain controlled fatigue.
• The connection between fatigue crack and creep voids could rapidly accelerate crack propagation.

This paper describes a characteristic damage propagation mechanism in low-cycle creep–fatigue of Cu–0.7Cr–0.09Zr (mass%), as investigated by creep–fatigue tests including strain controlled fatigue and stress-holding type creep, and following microstructural observations by scanning electron microscopy (SEM). The total stress-holding time until rupture in the creep–fatigue test was shorter than one-tenth of the rupture life in the simple creep test, and the rupture life of the specimen in the creep–fatigue test was shorter than half of that in the simple fatigue test. The SEM images suggest that the connection between fatigue crack propagating along grain boundaries and intergranular creep voids rapidly accelerates crack propagation.

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