The present review evaluates recent advances in the development of Welding-Based
Additive Manufacturing (WBAM) technologies using arc, high-energy density,
solid-state, and hybrid welding systems by providing an interdisciplinary
assessment of technological aspects, sensing, process optimization, and
multi-process strategies. It is concluded that, in spite of considerable
progress in process optimization and control, there exist numerous paradoxes
associated with relationships among process conditions, structure, and
properties, especially those related to heat input effects on material
microstructure and performance. An important finding is the fragmentation of
predictive modeling approaches, where physics-based and data-driven methods
remain inadequately integrated, limiting generalizability and accuracy. Another
important conclusion is related to the dominance of the effect of thermal
history and multi-physical phenomena on the mechanical performance of the
material produced by WBAM technologies. Besides, the complexity and
contradiction in defect generation mechanisms, monitoring, and evaluation
methodologies restrict the development of process standardization and
certification. New directions in intelligent fabrication based on artificial
intelligence and digital twins are identified.
