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Long-term corrosion evaluation of stainless steels in Space Shuttle iodinated resin and waterThe effects of stainless steel exposure to iodinated water is a concern in developing the Integrated Water System (IWS) for Space Station Freedom. The IWS has a life requirement of 30 years, but the effects of general and localized corrosion over such a long period have not been determined for the candidate materials. In 1978, Umpqua Research Center immersed stainless steel 316L, 321, and 347 specimens in a solution of deionized water and the Space Shuttle microbial check valve resin. In April 1990, the solution was chemically analyzed to determine the level of corrosion formed, and the surface of each specimen was examined with scanning electron microscopy and metallography to determine the extent of general and pitting corrosion. This examination showed that the attack on the stainless steels was negligible and never penetrated past the first grain boundary layer. Of the three alloys, 316L performed the best; however, all three materials proved to be compatible with an aqueous iodine environment. In addition to the specimens exposed to aqueous iodine, a stainless steel specimen (unspecified alloy) was exposed to moist microbial check valve resin and air for a comparable period. This environment allowed contact of the metal to the resin as well as to the iodine vapor. Since the particular stainless steel alloy was not known, energy dispersive spectroscopy was used to determine that this alloy was stainless steel 301. The intergranular corrosion found on the specimen was limited to the first grain boundary layer.
Document ID
19920008158
Document Type
Technical Memorandum (TM)
Authors
Krohn, Douglas D. (NASA Lyndon B. Johnson Space Center Houston, TX, United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1992
Subject Category
METALLIC MATERIALS
Report/Patent Number
NASA-TM-104743
S-660
NAS 1.15:104743
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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