Optimization of Process Parameters and Mechanical Properties of 316L Stainless Steel Block via Arc Additive Manufacturing

Abstract

A study was conducted on the influence of current, spacing, current mode, and arc length on the formation of adjacent weld overlays in the 316L stainless steel block melting process using an extremely inert gas-shielded arc additive manufacturing method. The main defect observed during the formation of adjacent weld overlays was the incomplete fusion at the bottom. When using direct current, low current and short arc length could ensure the flatness of the overlay surface, and the fusion at the bottom of the adjacent weld overlays was improved, but the problem of incomplete fusion remained unresolved. When using pulse current, low current, short arc length, and continuous welding method could solve the problem of bottom fusion of adjacent weld overlays. Due to the thermal influence during the accumulation of adjacent weld overlays, the microstructure inside the weld overlay was uneven, and the crystallographic texture in the entire weld overlay was not formed. With a pulse current of 80 A, adjacent weld overlay spacing of 4.5 mm, travel speed of 200 mm/min, dry elongation of 10 mm, and arc length of 2 mm, the tensile strengths of the block in the X, Y, and Z directions were 568.5, 570.3, and 550.7 MPa, respectively, and the fracture elongations were 46%, 48%, and 43.3%, respectively. The strength and plasticity in the Z-direction were lower than those in the X and Y directions. The 316L stainless steel had excellent mechanical properties, corrosion resistance, and low-temperature performance (Tan et al. 2019; Larimian et al. 2022). It was commonly used in the manufacturing of marine equipment, such as offshore oil platforms or large ships, and had a wide range of applications in industries, such as automotive and aerospace (Zhang et al. 2021b; Zhao et al. 2021a, 2022b). Compared with laser additive manufacturing, arc additive manufacturing had the advantages of low cost and high efficiency, although its forming accuracy was low (Casati et al. 2016; Zhang et al. 2021a; Zhao et al. 2022a). It was suitable for the customized manufacturing and maintenance of large structures.