Additive Manufacturing Bulk Parameter's Influence on Surface Roughness, Microstructure, and Fatigue

Additive manufacturing (AM) provides the ability to fabricate complex geometries where the material is created at the same time as the component. Typically, it is assumed that laser powers and speeds in the bulk parameters influence the internal microstructure and porosity, while the contour parameters control the surface roughness. However, in this work, the bulk processing parameters have been changed when fabricating axial fatigue specimens, which modifies the microstructure. However, the surface is also influenced because the bulk over-melted the contours to dominate the surface roughness. Axial fatigue testing results suggest that surface roughness is still the dominating factor in the total life with a significant influence on fatigue initiation, with less significant difference from different microstructures on the fatigue growth life. Understanding the processing-structure-properties-performance relationships is critical in AM. However, these relationships must include the interactions between parameter sets, such as bulk parameter influence on the surface roughness and the resulting effect on fatigue failure mechanisms.

Automated summary

Additive manufacturing allows for the creation of complex geometries by simultaneously fabricating the material and the component. In this study, the bulk processing parameters were modified during the fabrication of axial fatigue specimens, resulting in changes to both the microstructure and surface roughness. The axial fatigue testing revealed that surface roughness plays a significant role in fatigue initiation and has a greater influence on total life compared to differences in microstructures. Understanding the relationships between processing, structure, properties, and performance is crucial in additive manufacturing, including the interactions between different parameter sets and their effects on fatigue failure mechanisms.