Mechanical behavior of austenitic stainless steels produced by wire arc additive manufacturing

Abstract

Wire arc additive manufacturing (WAAM) is an innovative technology with the potential to drive the transformation and upgrading of metallic manufacturing industry and construction sector. The advantages of WAAM technology in rapid manufacturing, design freedom, and energy saving have attracted attentions in the construction field. This research study focuses on investigating the microstructural and mechanical behavior of austenitic stainless steels produced by wire arc additive manufacturing through test programs. The stainless steel plates were first additively manufactured using cold metal transfer technology with three types of feedstock wires (ER304, ER308L, ER316L). Tensile coupon specimens and microstructural observation samples were extracted from the WAAM plates. The electron backscatter diffraction (EBSD) experiments were conducted to identify and analyze the microstructures of the WAAM austenitic stainless steels. Five test orientations, namely θ = 0˚, 30˚, 45˚, 60˚, 90˚ relative to the printing layer direction, were designed to investigate the mechanical properties anisotropy. Two types of specimen surface condition (milled type and as-built type) were considered to assess the impact of geometric undulation. The geometric features of the as-built specimens were obtained using 3D laser scanning. A total of 60 tensile tests with the aid of digital image correlation (DIC) system were conducted to obtain the stress–strain responses of the WAAM austenitic stainless steels. The mechanical properties anisotropy of the WAAM austenitic stainless steels was analyzed in detail.