In Situ Curing‐Enabled 3D Printing of Continuous Fiber‐Reinforced Thermosetting Composites

Additive manufacturing (AM) of continuous fiber‐reinforced thermoset composites (CFTCs) is emerging as a rapid, flexible, and cost‐effective custom manufacturing route to lightweight structures with excellent mechanical performance. In situ 3D printing of CFTCs integrates fiber placement and impregnation with in‐process curing and consolidation, reducing post‐processing and improving scalability. Despite these advantages, reliable printing demands deliberate resin design that simultaneously delivers rapid polymerization kinetics and suitable rheology, together with precise control of curing power and fiber wet‐out, and careful matching of printing speed to the curing rate. This review surveys state‐of‐the‐art in situ curing strategies for 3D‐printed CFTCs, including radiation‐induced curing, photothermal and electrothermal curing, and frontal polymerization. We discuss the underlying curing mechanisms and process configurations that govern gelation, consolidation, and freestanding printability. This review synthesizes recent studies to clarify the key factors governing the mechanical performance of 3D‐printed CFTCs and to elucidate how different strategies optimize interfacial quality, reduce void content, improve consolidation, and control fiber volume fraction and alignment. The early‐stage role of artificial intelligence (AI) and data‐assisted approaches in process monitoring, optimization, and performance prediction is also discussed. Finally, key challenges and future directions are outlined to advance the mechanical reliability, scalability, and sustainability of 3D‐printed CFTCs.