Microstructural characteristics, mechanical performance and constitutive modelling parameters of additively manufactured copper under quasi-static and dynamic loading conditions

• The mechanical properties of additively manufactured copper are determined and compared against those of conventional machined copper in quasi-static and high strain-rate loading conditions. • The effects of printing direction on porosity features and mechanical properties are analysed through XCT scanning, quasi-static and dynamic mechanical experiments, as well as the Taylor impact test. • The constitutive modelling parameters for additively manufactured copper are determined from the mechanical test data and validated for high strain-rate loading conditions. This paper comprehensively investigates the mechanical responses of additively manufactured (AM) copper for two build orientations using the Atomic Diffusion Additive Manufacturing (ADAM) process, compared against two representative types of conventionally machined (CM) copper. For the latter, each CM copper leans towards an aspect of the strength-ductility trade off, hence provide a range of mechanical properties for the benchmarking of AM copper. Through a series of quasi-static and dynamical mechanical tests, the tensile and compressive characteristics are compared and contrasted for the different copper specimens at various strain rates. For the AM copper specimens, XCT analysis revealed a distinctive pore distribution between adjacent print layers to induce a corresponding macroscopic anisotropy and tension-compression asymmetry behavior. The specimen built with the printing direction perpendicular to its major axis (AM-H) displayed a favourable balance of strength and ductility when compared to CM, while the specimen printed parallel to the major axis (AM-V) showed the lowest strength and ductility among the AM samples. Except for one type of CM copper (CM-1 representing the high-yield-strength variant), all materials exhibited obvious strain hardening and strain-rate sensitivity. Finally, the Johnson-Cook constitutive modelling parameters are determined for the AM copper specimens and validated against the experimental Taylor impact test data. These findings thus offer valuable insights into the mechanical performance of AM copper to facilitate the optimization of material design and process improvement for high-strain rate impact applications.