Understanding the Mechanism of Stress Corrosion Cracking Resistance in Stainless Steel Welds Subjected to Laser Shock Peening without Coating for Nuclear Canister Applications

John, Merbin; Ralls, Alessandro M.; Misra, Manoranjan; Menezes, Pradeep L.

doi:10.1007/s11665-023-09098-4

Cited by 8 publications

(1 citation statement)

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“…Studies also indicated that pitting and cracking under stresses and salt environments should preferably occur with high tensile residual stresses at locations containing δ-ferrite, high tensile residual stresses at locations containing δ-ferrite, which is generally seen in austenitic SS welds [12,16]. Post-welding processes, such as surface mechanical deformation using peening, dramatically reduced SS weld tensile residual stresses [17], and the resulting welded joint had improved SCC resistance [18,19]. However, post-welding mechanical processes increase the manufacturing cost, and cold work effects may degrade gradually when exposed to radiation.…”

Section: Introductionmentioning

confidence: 99%

Study of Mechanical Properties, Microstructure, and Residual Stresses of AISI 304/304L Stainless Steel Submerged Arc Weld for Spent Fuel Dry Storage Systems

Tang,

Chatzidakis,

Schrad

et al. 2024

Metals

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The confinement boundaries of spent nuclear fuel (SNF) canisters are typically fusion welded. Welded microstructures, strain hardening, and residual stresses combined with a chemically aggressive, chloride-rich environment led to concerns that the welded canister may be susceptible to chloride-induced stress corrosion cracking (CISCC). A comprehensive understanding of the modification of stainless steel (SS) metallurgical and mechanical properties by fusion welding could accelerate the predictive analysis of CISCC susceptibility. This paper describes a submerged arc welding (SAW) procedure that was developed and qualified on 12.7 mm (0.5 in.) thick AISI 304/304L SS to produce joints in a way similar to actual SNF canister manufacturing. This procedure has the potential to reduce the production cost and weld CISCC susceptibility by using fewer welding passes and lower heat input than current industrial applications. Global and local mechanical behaviors and properties, as well as residual stress distributions on the welded joint, were studied. The results indicate that hardness values in the fusion zone (FZ) and heat-affected zone (HAZ) are slightly higher than that of the base metal. Strain localization was presented in the HAZ before the tensile stress reached its maximum value, and then it shifted to the FZ. The specimen finally broke in the FZ. High tensile residual stresses exhibited in the FZ and the nearby HAZ suggest the highest CISCC-susceptible spots. The maximum tensile residual stresses were along the welding direction, indicating that if cracks occur, they would be perpendicular to the welding direction. This study involved developing and qualifying a SAW procedure for SNF canister production. The new procedure yielded cost savings (SAW working efficiency increased by about 80%), improved mechanical properties, and presented moderate residual stresses. Analysis revealed that the welded joint’s low-stress and high-stress damage assessments may be affected by shifts in the strain localization spot under loading.

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