Temperature Regulation Trade‐Offs in Laser Directed Energy Deposition of Titanium Alloys: Mechanisms, Bottlenecks, and Outlook

Laser directed energy deposition (LDED) has become an important technology for fabricating and repairing titanium alloy components in aerospace and high‐end equipment applications. However, its highly non‐equilibrium thermal history may create coupled challenges in geometric accuracy, defect control, microstructure evolution, and mechanical performance. This review summarizes recent progress in temperature regulation during LDED of titanium alloys, with emphasis on the full‐cycle evolution of the temperature field and four key variables: peak melt‐pool temperature, temperature gradient, cooling rate, and heat accumulation. The influences of temperature‐field evolution on defects, microstructure, residual stress, and mechanical properties are discussed, and the trade‐off mechanisms among defect suppression, microstructural optimization, and property enhancement are analyzed. Temperature‐field simulation, in situ monitoring, and closed‐loop control strategies are also reviewed. Available studies suggest that many regulation strategies may exhibit bidirectional effects, and it remains difficult to define a universally applicable optimum using a single parameter. Effective control generally depends on coordinated parameter windows adapted to component geometry, material system, and service requirements. Future work should further develop quantitative multi‐defect evolution models, multi‐objective optimization, and intelligent closed‐loop regulation integrating thermal, mechanical, and microstructural responses.