Crystallographic texture and velocities of ultrasonic waves in a Ni-based superalloy manufactured by laser powder bed fusion

Abstract

This study investigated the mechanisms of formation of the microstructure and texture of an Inconel 625 manufactured by additive manufacturing, using laser-based powder bed fusion. The resulting texture has a quadratic symmetry and a composite organization of grains. Some elongated grains have their 〈100〉 aligned along the build-up direction and grow from the middle of the melt pool, whereas the others are inclined with a lower texture. This is explained on the basis of usual solidification mechanisms. The overall texture is not very pronounced (texture index of 1.24) but sufficient to influence ultrasound wave propagation in a measurable manner. The difference is the most pronounced between the slow and fast quasi transverse waves. The contribution of two main factors influencing the anisotropy, namely the anisotropy of the single crystal and the shape of the grains, are discussed in the paper.