Characterization of Asymmetric and Anisotropic Plastic Flow of L-PBF AlSi10Mg

Background

Understanding and predicting the behavior of additively manufactured (AM) parts in real-case scenarios is essential for optimizing the design process. Little literature presents a throughout investigation on the influence of the stress state on the anisotropic response of AM materials, and there has not been a great effort to validate the applicability of conventional material models for AM components.

Objective

This work aims to assess the effect of building orientation and the stress state on the mechanical response of as-built laser powder bed fusion (L-PBF) AlSi10Mg and to propose, based on the experimental results, a material model able to represent its mechanical response thoroughly.

Methods

Several mechanical characterization tests, including uniaxial tensile and compressive tests, tensile tests on round-notched bars, and shear tests, were carried out for each investigated building direction (0°, 45°, 90°). The Cazacu-Barlat yield surface was selected to describe the mechanical behavior of the material. Material parameters were identified by inverse calibration and verified using finite element simulation of performed experimental tests.

Results

The results showed a more consistent effect of the building direction on ductility and maximum stress value, while the effect on yield stress was less significant. Under multiaxial stress states, the anisotropic behavior became less noticeable yet present. No anisotropic behavior was observed under shear conditions. In tension and compression, a slight asymmetry in response was noted. Computational results were found in agreement with the experimental data.

Conclusion

The influence of both stress state and of the building direction has been systematically investigated by performing several characterization tests on different sample geometries. In combination with mechanical testing, a material model has been proposed and validated to show the applicability of conventional modeling techniques to AM material.