Analysis of mechanical and metallurgical properties of HSLA fabricated by wire and arc additive manufacturing (WAAM)

A customized WAAM torch was attached to a 3-axis CNC machine within a working envelope of 2760 × 1960 × 2000 mm and a welding machine from Oerlikon, with a power source CITOWAVE III 520, wire feeder and control unit DMU W500 was used to deposit the material over a mild steel substrate. The feedstock material was a commercial low-carbon high-strength steel AWS A5.28 ER110S-G wire electrode with a diameter of 1 mm. ARCAL™ (Ar 82% / CO2 18%) was used as shielding gas and the deposition strategy was the Zig-Zag, i.e. consecutive layers were deposited in opposite directions. The samples were manufactured with 50 layers to carry out mechanical and metallographic tests. Uniaxial tensile tests were performed on an Autograph Shimadzu machine model AG500Kng equipped with a Shimadzu load cell SFL-50kN AG. For each condition, four specimens were removed in the longitudinal direction and four specimens in the transverse direction. The micro-specimens with a thickness of 2.5 mm were extracted via electro discharge machining (EDM), and the geometry was designed on the basis of standards according to the recommendations of ASTM E8-04, DIN EN 2002-001:2006-11 and DIN EN ISO 6892-1:2009-12. Impact tests were performed with a Charpy pendulum (300 J capacity) on V- notch sub-sized samples with dimensions of 55 mm × 10 mm × 2,5 mm according to the specifications given by EN ISO 148–1:2016 [1]. For microstructural characterization, cross- sections from the center of each sample were cut, polished, and etched with Nital (2%). The metallographic analysis was conducted using a Leica DMI 5000 M inverted optical microscope.