Radiation-induced microstructural evolution in cold-worked steels: the role of dislocations and competing defect sinks in nuclear materials – a review

Radiation effects in metallic materials have been extensively studied; however, the interpretation of radiation tolerance remains challenging due to the complex interaction between defect generation, microstructural evolution, and alloy chemistry. This review provides a conceptual framework to connect radiation damage mechanisms with processing–microstructure relationships in steels and advanced metallic alloys, facilitating the integration of knowledge among materials scientists, metallurgists, and nuclear engineers. The development of structural materials for Generation IV reactors, fusion systems, and extreme radiation environments requires a comprehensive understanding of how radiation-induced defects evolve and interact with the surrounding microstructure. Radiation exposure generates point defects, defect clusters, and radiation-enhanced diffusion processes that modify phase stability and mechanical properties. In this context, defect sinks such as dislocations, grain boundaries, interfaces, and nanoscale precipitates play a critical role in controlling defect evolution. Cold drawing provides an industrially relevant approach to increase dislocation density in steels, modifying not only defect absorption capacity but also radiation-enhanced diffusion and solute redistribution processes. Studies on reactor pressure vessel steels demonstrate that vacancy–solute interactions promote the formation of Cu-rich and Mn–Ni–Si-rich clusters, which contribute significantly to irradiation hardening. Similarly, cold-worked alloys show that pre-existing dislocation structures can influence irradiation-induced precipitation and phase evolution, demonstrating the coupling between deformation, chemistry, and radiation response. A quantitative comparison of representative defect sink strengths indicates that dislocation networks generated by cold deformation can reach values comparable to engineered sinks, including oxide dispersions and refined grain structures. Nevertheless, radiation tolerance is not governed by a single microstructural parameter, since sink stability, irradiation conditions, alloy chemistry, and defect–solute interactions determine the effectiveness of each mechanism. High-entropy alloys (HEAs) provide new opportunities for radiation-resistant materials; however, recent studies demonstrate that chemical complexity alone does not ensure phase stability, as thermal exposure and irradiation can promote segregation, precipitation, and phase decomposition. Therefore, this review proposes that radiation tolerance should be understood as a coupled microstructure–chemistry phenomenon, where dislocation structures, defect sinks, solute redistribution, and phase stability collectively determine irradiation hardening and degradation behavior.