Optimization of process parameters in wire arc additive manufacturing for strengthening cracked steel plates: A thermo-mechanical study

Wire Arc Additive Manufacturing (WAAM) also known as wire arc-based directed energy deposition (WA-DED) has emerged as a promising technology for repairing and strengthening steel structures. This study investigates the optimization of key process parameters in the WAAM process to improve residual stress (RS) distribution and structural integrity of cracked steel plates. A thermo-mechanical finite element model is developed and validated to predict temperature evolution and RS profiles. Following determination of the optimal dwell time type, the effects of travel speed, dwell time, and substrate preheating temperature on thermal history, RS distribution at the WAAM/plate interface, and maximum stress under external loading are systematically analyzed. The results reveal that increasing travel speed effectively reduces tensile residual stresses, while extended dwell times lead to higher residual and maximum stresses due to increased thermal gradients. Additionally, substrate preheating significantly lowers tensile residual stresses but also reduces compressive stresses near the crack tip, which may influence crack arrest effectiveness. By optimizing the combination of process parameters, reductions of up to 40 % in both maximum residual stress and maximum stress under external loading were achieved. These findings provide valuable insights for enhancing the fatigue performance and structural reliability of WAAM-strengthened steel components.