Characterization of the Strain-Rate-Dependent Plasticity of Alloys Using Instrumented Indentation Tests

Abstract

Instrumented indentation tests are an efficient approach for the characterization of stress–strain curves instead of tensile or compression tests and have recently been applied for the evaluation of mechanical properties at elevated temperatures. In high-temperature tests, the rate dependence of the applied load appears to be dominant. In this study, the strain-rate-dependent plasticity in instrumented indentation tests at high temperatures was characterized through the assimilation of experiments with a simulation model. Accordingly, a simple constitutive model of strain-rate-dependent plasticity was defined, and the material constants were determined to minimize the difference between the experimental results and the corresponding simulations at a constant high temperature. Finite element simulations using a few estimated mechanical properties were compared with the corresponding experiments in compression tests at the same temperature for the validation of the estimated material responses. The constitutive model and determined material constants can reproduce the strain-rate-dependent material behavior under various loading speeds in instrumented indentation tests; however, the load level of computational simulations is lower than those of the experiments in the compression tests. These results indicate that the local mechanical responses evaluated in the instrumented indentation tests were not consistent with the bulk responses in the compression tests at high temperature. Consequently, the bulk properties were not able to be characterized using instrumented indentation tests at high temperature because of the scale effect.

Multiscale Modelling and Characterization of Mechanical Properties in Heat-Resistant Alloys

“…T. Saito et al [1] and T. Chen et al [2] investigated creep behavior; T. Saito et al [1] focused on the deformation mechanism of a single-crystal high-entropy superalloy at intermediate temperature from theoretical and experimental aspects. T. Chen et al [2] developed a measurement method of strain-rate-dependent plasticity using a high-temperature instrumented indentation test and its computational simulations.…”

“…Saito et al [1] and T. Chen et al [2] investigated creep behavior; T. Saito et al [1] focused on the deformation mechanism of a single-crystal high-entropy superalloy at intermediate temperature from theoretical and experimental aspects. T. Chen et al [2] developed a measurement method of strain-rate-dependent plasticity using a high-temperature instrumented indentation test and its computational simulations. E. Bonifaz and I. Watanabe [3] developed a multiscale simulation method for an arc-welded joint, in which the residual stress state after the welding process was estimated in consideration of the anisotropic microstructure.…”