• Lathabai, Sri
• Ritchie, David
• Shubo, Gao
• Raman, Sudharshan
• Gaskey, Bernard
• Seita, Matteo

Abstract

Additive manufacturing (AM) enables the fabrication of components with topology-optimized geometries, owing to the layer by layer nature of the process. Because material and geometry are formed concurrently, however, AM also provides location-specific control over the microstructure of the fabricated components. This capability opens the path to manufacturing parts that integrate multiple microstructures—and thus multiple properties—which are optimized for a specific application. Many studies have addressed the effects of scan speed, laser power, hatch spacing and layer thickness on the resulting microstructure. By contrast, we choose to vary the laser scan direction in each layer. We select stainless steel 316L as a model material due to its widespread use in the AM community. We use selective laser melting to fabricate samples by continuously changing the scan rotation throughout the layers while holding other build parameters constant. We characterize the samples microstructure by means of EBSD and investigate their corrosion properties using long-duration open circuit potential and cyclic potentiodynamic polarization measurements. We find that the laser scan direction has a direct effect on the material’s microstructure and corrosion behaviour. We discuss the results in terms of the directional solidification process during AM and the possible design of corrosion-resistant steels with multiple microstructures for Marine applications

Topics

• microstructure
• stainless steel
• corrosion
• selective laser melting
• electron backscatter diffraction
• directional solidification