Microstructural and Mechanical Characterization of ER310 Stainless Steel Produced by Dual-Wire Laser Additive Manufacturing

Wire Laser Additive Manufacturing (WLAM) has emerged as a promising directed energy deposition technology, combining the high deposition efficiency of wire-fed processes with the localized heat input and dimensional accuracy provided by laser processing. However, studies on heat-resistant austenitic stainless steels, particularly ER310 processed using a dual-wire TANDEM configuration, remain limited. This study investigates the microstructural evolution, thermal behavior, chemical composition, and mechanical properties of ER310 stainless steel fabricated by dual-wire WLAM. A 100-layer wall, approximately 150 mm in height, was deposited on an AISI 304 substrate using two 1.2 mm ER310 wires, a laser power of 1700 W, a wire feed rate of 50 cm/min per wire, a laser oscillation speed of 350 mm/s, and argon shielding. Characterization included optical emission spectroscopy (OES), optical microscopy, SEM/EDS, X-ray diffraction (XRD), thermographic monitoring, Vickers microhardness testing, and tensile testing in the 0°, 45°, and 90° build orientations. Thermographic monitoring recorded peak surface temperatures of up to 1733.4 ± 15 °C. OES showed that the chemical composition remained consistent with that of ER310, with 26.08 wt.% Cr, 20.71 wt.% Ni, and 50.79 wt.% Fe. The deposited wall exhibited a predominantly austenitic microstructure, characterized by both columnar directional growth and regions containing polygonal grains, with localized Cr and Mn segregation at grain boundaries identified by SEM/EDS. The average microhardness was 182 ± 5.7 HV, with limited variation across the analyzed region. Tensile testing revealed anisotropic behavior, with the 0° orientation exhibiting the highest yield strength (345 ± 5.6 MPa), ultimate tensile strength (434 ± 12 MPa), and engineering strain (13.1 ± 0.35%), compared with engineering strains of 8.4 ± 0.17% at 45° and 12.0 ± 0.2% at 90°. These results demonstrate the feasibility of dual-wire WLAM for fabricating ER310 components while maintaining the expected chemical composition and predominantly austenitic microstructure, with mechanical properties comparable to those reported for ER310 produced by other additive manufacturing processes.