Advanced synchrotron X-ray analysis of diffraction elastic constants in additively manufactured textured metastable steels

Additive manufacturing (AM) is a key toward digital manufacturing (Industry 4.0). However, industrial applications still suffer research gaps in terms of understanding of materials characteristics. Amongst others, this is due to intrinsic heat treatment and solidification-induced residual stress. To address the latter, volume expansion via phase transformation can be exploited to balance thermal contraction. The challenge here is understand the complexity of multiple phase transformations, which cannot be fully assessed using standard post-process methods. In situ characterization methods are needed to better understand these fundamental mechanisms. Furthermore, appropriate AM parameters can directly affect the microstructure. Results available reveal that the characteristics of AM microstructures can have a significant impact on established parameters like diffraction elastic constants (DEC). This is very important, as DEC deduced from conventionally processed material cannot be directly used for assessment of AM processed materials. This present study focuses on in situ energy dispersive analysis of metastable steels processed via AM under uniaxial tension, with the aim of assessing how DEC are affected by coarse-grained and textured microstructures. For this purpose, three grades of 16Cr-6Mn-XNi steel with varying Ni content are analysed, taking into account their orientation-dependent behaviour.