Evaluation of material properties of 3D printed carbon steel for material modelling

A procedure and material properties of tensile coupon specimens are presented. The coupon specimens were cut from the plates printed by ArcelorMittal Global R&D Bars & Wires. For this, a welding robot based on Wire Arc Additive Manufacturing (WAAM) procedure and welding wire AWS 5.18 ER70S-6 Böhler K56 were used. The specimens were cut in different directions to the printing direction, to investigate possible material anisotropy. Surface milled and as printed specimens were investigated focusing on the influence of surface irregularities on the material behaviour. 2D Digital Image Correlation (DIC) was used for evaluating engineering stress-strain diagrams, E-modules and Poisson ratios for each specimen. Obtained results clearly indicate that 3D printing technology was appropriate, showing material properties rather close to the rolled mild steel and minor anisotropy, E=200GPa, fracture strain above 25%, strength/yield stress beyond 1,3, for fy=420 MPa. Roughness of the surface was just 0,2mm for the thickness of 3,7mm, obtained using the wire diameter of 3mm. Finite Element Method (FEM) was used to validate the experimental results and to calibrate damage material properties. Results of uniaxial coupon specimens, the stress-strain curve, is divided in 3 stages: the elastic stage, the plastic stage and the coupled plastic stage. The coupled plastic-damage stage is further decomposed into the plastic-dominated zone and the damage-dominated zone. The true stress-strain curve after necking is calibrated by FEM. © 2021 Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin.