Study on microstructure change and hardening of 316L steel weld seam after helium ion irradiation

Abstract In order to explore the microstructure changes and hardening of austenitic stainless steel weld seam after helium ion irradiation, three sets of 316 Lweld seam samples with different welding parameters were irradiated with 100 KeV, 2 × 1017n/cm2 He+. It is found that the residual tensile stress in the weld seam strengthens, the average size of the Frank loops changed to 7.8 nm, 13.3 nm, and 14.3 nm, respectively, and the weld hardening degree increased with the increase of the welding speed. The difference sizes of the Frank loops observed in the three sets of samples may be due to the different residual tensile stress of weld seams, which could promote the aggregation of interstitial atoms. However, there may be two reasons for the different degree of radiation hardening: One is that the increased size of dislocation loops hinders dislocation motion, another is that grain refinement could increase the degree of radiation hardening.