Title: On residual stress analysis and microstructural evolution for stainless steel type 304 spent nuclear fuel canisters weld joint: Numerical and experimental studies

Abstract

Chloride-induced stress corrosion cracking (CISCC) in the weldments of austenitic stainless steel canisters is one of the primary safety concerns during the dry storage of used nuclear fuel at Independent Spent Fuel Storage Installations in coastal areas. In order to evaluate the CISCC behavior in the canister, a 3D sequentially coupled thermo-mechanical finite element model was built to simulate the residual stresses induced by two intersecting longitudinal and circumferential multi-pass welds in austenitic stainless steel mockup canister. Weld-induced residual stresses from simulation were in good agreement with the experimental measurement results by deep-hole drilling and contour methods. Through-wall high tensile axial and hoop stresses were observed in both the fusion zone and heat affected zone (HAZ) in the longitudinal and circumferential weld, respectively. On the other hand, the microstructure within the weldments of 304 stainless steel mockup was characterized using optical microscopy, scanning electron microscopy, electron back-scattered diffraction and energy dispersive X-ray spectroscopy methods. A few amount of MnS inclusions in both the base metal and HAZ, and a lot of (Mn,Si)_xO_y inclusions in the fusion zone were found. Meanwhile, there is some α'-martensite in the base metal, while the martensite was reversed in the HAZ. In the fusion zone,more » there is a lot of δ-ferrite. The martensite reversion phenomenon was also verified by the combination of Feritscope test and thermal simulation, which could predict a martensite reversion temperature as 400C°. The welding residual stresses and microstructure analysis results could offer the instructive information for the prediction of CISCC behavior of the spent nuclear fuel canisters.« less

Authors:

Wu, Xin ^[1]

---

+ Show Author Affiliations

1. Colorado School of Mines, Golden, CO (United States)

Publication Date:

Wed Apr 01 00:00:00 EDT 2020

Research Org.:

Colorado School of Mines, Golden, CO (United States)

Sponsoring Org.:

USDOE Office of Nuclear Energy (NE), Nuclear Energy University Program (NEUP); USDOE

OSTI Identifier:

1801224

Alternate Identifier(s):

OSTI ID: 1608361

Grant/Contract Number:  

NE0008442

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Nuclear Materials

Additional Journal Information:

Journal Volume: 534; Journal ID: ISSN 0022-3115

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; stress corrosion cracking; spent nuclear fuel canister; welding residual stress; finite element simulation; microstructure