Anisotropic Mechanical Behavior of Additive Manufactured AISI 316L Steel

We investigated the relationship between the microstructure and mechanical properties of additive manufactured AISI 316L steel regarding the grain aspect ratio and orientation. For this purpose, two types of specimen (vertically and horizontally built) were prepared by a selective laser melting process, and the mechanical behavior was evaluated in different tensile directions. After this, to observe the characteristic grain boundary distributions such as grain size, shape, orientation, and intergranular misorientation, electron backscattering diffraction analysis was conducted on the initial and tensile-strained specimens. The specimen with a lower grain aspect ratio showed enhanced yield and tensile strengths arising from the higher strain hardening rate relative to the specimen with higher grain aspect ratio. In addition, the material composed of grains with a higher Taylor factor showed more accumulated dislocation density during tensile deformation when compared to the material composed of grains with a lower Taylor factor, which also contributed to the increase in tensile strengths because of the enhanced strain hardening rate.