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23rd Edition:Probing the causes of corrosion in welded 316L stainless steel |
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Jul 01, 2004 at 12:00 AM |
Gerhard Schiroky & Gary Henrich, Swagelok Company
ABSTRACT
A study was performed to determine the corrosion
behavior of welded tube samples of ultralow-manganese and low-manganese
316L alloys in corrosive gaseous environments. First, a weld-fume
analysis was performed to determine which elements evaporate to a
significant extent during orbital welding with 316L test samples
containing different amounts of manganese. Second, welded tube sections
were exposed to corrosive gases and the surfaces were characterized by
scanning electron microscopy (SEM) both in the short term (24 h) and in
the long term (28 days). It has been claimed that during welding, the
manganese evaporates from the weld pool and redeposits in the
heat-affected zone, primarily downstream of the weld pool, causing
corrosion to occur.
However, this study showed that all sample alloys
demonstrated very similar corrosion behavior, and they released
predominantly iron in approximately the same amount. Thus, it is
believed that the evaporation and redeposition of iron, not manganese,
negatively impacts the corrosion resistance of welded low-manganese and
ultralowmanganese stainless steel alloys in chlorine-containing, moist,
gaseous atmospheres. The conclusions suggest that ultralow-manganese
alloys do not perform any better than less costly low-manganese alloys
when components are welded and subjected to corrosive (28 days)
atmospheres. Therefore, lowmanganese alloys should be selected by the
cost-conscious users of fluid-system components for the demanding
applications of semiconductor processing.
 03 - Probing the causes of corrosion in welded 316L stainless steel
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Critical Components 
