<b>IRRADIATION-ASSISTED STRESS CORROSION CRACKING OF 316L STAINLESS STEEL MANUFACTURED BY LASER DIRECTED ENERGY DEPOSITION USING MICROSTRUCTURALLY GRADED SPECIMEN</b>

<p dir="ltr">Different from traditional wrought 316L stainless steel (SS), the microstructure of 316L SS made by additive manufacturing (AM) 316L SS varies significantly depending on the manufacturing and heat treatment conditions. The effects of processing and microstructure on nuclear-related properties are needed as a regulatory basis to accept AM for nuclear use. However, a large parametric study of irradiation-assisted stress corrosion cracking (IASCC) in AM 316L SS is challenging due to the cost and time involved in evaluating IASCC. This study employed microstructurally graded specimens as a high-throughput method to evaluate IASCC behavior of AM 316L SS manufactured by directed energy deposition (DED) under a range of laser manufacturing parameters and heat treatment conditions. For the first time, three IASCC modes (intergranular, intragranular, and transgranular) were identified simultaneously on DED AM 316L SS; however, their contributions to the overall damage varied depending on the material conditions. Heat treatment showed the largest impact on cracking susceptibility with laser processing parameters exhibiting a secondary effect. The cracking susceptibility of DED AM 316L SS was highest in the 930℃ heat treatment, while the 650℃ and 1121℃ heat treatments showed lower magnitude. The contributions of various mechanistic factors to these IASCC modes, including dislocation cells, radiation hardening, manufacturing-related precipitates, and strain incompatibility caused by the broad grain size distribution, were discussed in detail.</p>