ASSESSMENT OF RESIDUAL STRESSES IN SRS AND HANFORD 3013 INNER AND CONVENIENCE CANS

[摘要] Chloride stress corrosion cracking (SCC) is a plausible corrosion mechanism for the stainless steel 3013 containers during their lifetime for plutonium material storage if sufficient electrolyte is present within the container. Contributing factors for SCC, such as fabrication and welding residual stresses, are present in the 3013 cans. Convenience and inner cans from both Hanford and SRS are made by a flow form process, which cold works the stainless steel during fabrication. Additionally, the inner cans also are sealed at the can top with a closure weld to the sealing plug. Only SRS and Hanford were tested since moisture levels were significant for SCC. As part of the 3013 corrosion plan for FY09, testing in a boiling magnesium chloride solution was performed on actual 3013 convenience and inner cans to determine if the residual stresses were sufficient for the initiation and propagation of SCC. Additional testing in a 40% calcium chloride solution was also performed on 304L stainless steel SCC coupons, i.e. stressed teardrop-shaped samples (teardrops), and an inner can welded top to provide comparative results and to assess the effect of residual stresses in a less aggressive environment. The testing performed under this task consisted of 3013 inner and convenience cans and 304L teardrops exposed to a boiling magnesium chloride solutions per ASTM G36 and a 40% calcium chloride solution at 100 C following the guidance of ASTM G123. Cracking occurred in all can types including the inner can bottom and welded top and the bottoms of the SRS and Hanford convenience cans when exposed to the boiling magnesium chloride solution at 155 C. Cracking occurred at different times indicative of the residual stress levels in the cans. 304L teardrops cracked in the shortest time interval and therefore provide a conservative estimate for can performance. Testing in a 40% calcium chloride solution at 100 C demonstrated that cracking occurs in a less aggressive environment but at significantly longer times than in the boiling magnesium chloride. Vapor space cracking was also found to occur in the inner can welded top exposed over the boiling magnesium chloride solution and on 304L teardrops exposed over a hot calcium chloride solution.

[发布日期] 2009-03-01

[学科分类] 材料科学（综合）

[关键词] BOILING;CALCIUM CHLORIDES;CHLORIDES;CLOSURES;CONTAINERS;CORROSION;ELECTROLYTES;FABRICATION;LIFETIME;MAGNESIUM CHLORIDES;MOISTURE;PERFORMANCE;PLUTONIUM;RESIDUAL STRESSES;STAINLESS STEELS;STORAGE;STRESS CORROSION;TESTING;WELDING