Wire arc additive manufacturing of steel structures: Guidelines and predictive equations

Wire arc additive manufacturing (WAAM), also known as wire-arc directed energy deposition (DED-Arc), has fostered a plethora of new opportunities for the design and manufacture of innovative, structurally efficient and architecturally playful forms of steel structures. Drawing from the experience gathered from the production of more than one tonne of WAAM specimens for structural testing purposes, the present paper provides step-by-step guidelines and practical insights for the WAAM of steel structures. The guidelines comprise six steps, describing, amongst others, the possible deposition and welding strategies, a systematic approach for the calibration of the process parameters and the classification of the print quality (into Classes A to D), the execution of the printing process, and the determination of the actual heat input. Importantly, new experimental data covering a wide range of process parameters are utilised to establish empirical predictive equations relating the process parameters with the nominal geometric characteristics (wall thickness and average layer height) of thin-walled WAAM steel elements. The key opportunities and potential applications of WAAM in steel construction, the design considerations for the development of WAAM facilities, and various practical challenges (alongside potential solutions) typically encountered in WAAM are also described. • Framework for wire arc additive manufacturing of steel structures is introduced. • Guidelines, challenges and solutions for WAAM of steel structures are presented. • Investigation matrix approach for calibration of process parameters is proposed. • New experimental data on influence of process parameters are presented. • Predictive equations relating process parameters to nominal geometry are developed.