| Sumitomo metal supplies 347AP(UNS S34751),
which has high corrosion resistance and high
strength for heating furnaces and reactors
in petroleum refinery plants.
347AP has excellent resistance to intergranular
stress corrosion cracking in welded joints
without post-weld heat treatment therfore,
347AP is widely used in petroleum
refineries in Japan.
Sumitomo 347AP is an austenitic stainless
steel which contains optimum amounts
of carbon, nitrogen and niobium. Low
carbon content prevents the grain boundary
precipitation of chromium carbides, which
cause intergranular stress corrosion
cracking. The addition of nitrogen compensates
for the reduction in strength due to
the lower carbon content of 347AP steel.
The high temperature strength of 347AP
is almost the same as that of conventional
TP347. The weldability of 347AP is better
than conventional TP347 due to the lower
niobium content.
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