Testing of Wire Arc Additively Manufactured Duplex Stainless Steel Double-Lap Shear Bolted Connections

The behavior and design of duplex stainless steel double-lap shear bolted connections produced by wire arc additive manufacturing (WAAM) are explored in this paper. A thorough experimental study carried out on 45 WAAM duplex stainless steel bolted connections with different bolt hole positions, surface conditions (milled or unmilled), and loading orientations relative to the printing direction is first presented. Details are described of the manufacturing process, which featured ER2209 feedstock wire, specimen geometries, which were determined via three-dimensional (3D) laser scanning, and testing of the bolted connection specimens. The failure modes, load-displacement responses, as well as strengths with and without consideration of the bolt hole deformation, are reported. The bolt hole position, rather than the loading orientation or surface condition, was found to have the strongest influence on the behavior of the tested WAAM duplex stainless steel double shear bolted connections. Given the lack of specific design rules for bolted connections between WAAM sheets, the applicability of existing design methods for conventional steel and stainless steel connections has been assessed. The connection test capacities were compared against the strengths predicted using the design expressions set out in three American specifications—AISC 360-22, AISC 370-21, and ASCE 8-22—and in the literature. It was found that existing design methods were generally able to predict the strengths of WAAM duplex stainless steel double shear bolted connections well, both with and without consideration of bolt hole deformation.