Spherical Indentation Behavior of DD6 Single-Crystal Nickel-Based Superalloy via Crystal Plasticity Finite Element Simulation

TL;DR

This paper uses simulations and experiments to study how DD6 nickel-based superalloy deforms under spherical indentation, focusing on the effects of loading rate and crystal orientation.

Contribution

The study introduces a CPFEM model incorporating dislocation density to simulate indentation behavior and explore texture evolution in DD6 alloy.

Findings

Maximum indentation depth increases and hardness decreases with prolonged loading time, showing strain rate strengthening.

Dislocation density and slip system strength increase with loading time at low loading rates.

Crystal orientation significantly affects mechanical behavior and texture evolution during indentation.

Abstract

Nickel-based superalloys are widely utilized in critical hot-end components, such as aeroengine turbine blades, owing to their exceptional high-temperature strength, creep resistance, and oxidation resistance. During service, these components are frequently subjected to complex localized loading, leading to non-uniform plastic deformation and microstructure evolution within the material. Combining nanoindentation experiments with the crystal plasticity finite element method (CPFEM), this study systematically investigates the effects of loading rate and crystal orientation on the elastoplastic deformation of DD6 alloy under spherical indenter loading. The results indicate that the maximum indentation depth increases and hardness decreases with prolonged loading time, exhibiting a significant strain rate strengthening effect. The CPFEM model incorporating dislocation density effectively simulates the nonlinear characteristics of the nanoindentation process and elucidates the evolution of dislocation density and slip system strength with indentation depth. At low loading rates, both dislocation density and slip system strength increase with loading time. Significant differences in mechanical behavior are observed across different crystal orientations, which correspond to the extent of lattice rotation during texture evolution. For the [111] orientation, crystal rotation is concentrated and highly regular, while the [001] orientation shows uniform texture evolution. This demonstrates that anisotropy governs the deformation mechanism through differential slip system activation and texture evolution.

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