Effect of Groove Shape on Irradiation Damage Resistance of CLAM Steel Welds

To investigate the effect of groove shape on theirradiation damage and hardening performance of Chinese low activation martensitic (CLAM) steel welds, scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), grazing incidence X-ray diffraction (GIXRD), and Nano-indentation technology were used to study the irradiation damage and mechanical properties of V-shaped, U-shaped, and double U-shaped CLAM steel welds after irradiation with He+ at an energy of 70 keV to a dose of 1×1017 ions/cm2 at room temperature. The results showed that after ion irradiation, defects such as helium bubbles and precipitates were generated in weld metals with different groove shapes, and the degree of reduction in mechanical performance varies. Compared with V-shaped and U-shaped groove welds, double U-shaped groove welds have a more uniform distribution and smaller sizes of internal defects after irradiation. This is because among the three types of welds, the double U-groove weld has a smaller heat input, a relatively smaller grain structure, and a higher grain boun-dary density. The higher density of grain boundaries hinders the mutual aggregation of defects, and reduces the size of defects. After irradiation, the surface roughness of the double U-shaped groove weld is the lowest, the size of helium bubbles and precipitates is the smallest, the diffraction peak offset and broadening rate are the lowest, the surface hardness is the lowest, and the irradiation hardening resistance is the best. This indicates that by controlling the shape of the welding groove and refining the grain structure of the weld, the irradiation damage resistance and irradiation hardening resistance of the weld can be significantly improved. © 2024 Cailiao Daobaoshe/ Materials Review. All rights reserved.