Experimental characterization and numerical analysis of additively manufactured mild steel under monotonic loading conditions

Additive Manufacturing (AM), for the case of metals, is a technology developed to create 3D products by following a layer-by-layer welding procedure. In this work, the tensile behavior of wire arc additively manufactured mild steel is studied experimentally and numerically. The microstructure of the metal is strongly influenced by the AM process that involves several heating and cooling cycles; therefore, it is first analyzed with optical microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction to identify the different phases and to extract the grain properties. With this information, two approaches are used to build the Representative Volume Element, which will be part of a multi-scale material model. The first approach constitutes a synthetic generation of grains according to a Voronoi Tessellation and the second one an image-based representation. Afterwards, a virtual tensile test for the determination of the stress-strain relation of the material is performed, which is later compared with the measurements of a real tensile test carried out on several specimens that were obtained using the wire arc additive manufacturing technique.It can be observed that the influence of the welding direction on the stiffness and the ductility of the additively manufactured steel product is rather low, yielding similar results in both parallel and perpendicular directions. Additionally, a softening behavior of the material is noticed.