Stainless Steel 347
|
MICC Sheath types |
UNS ref |
DIN ref. |
|
347 |
S34700 |
1.4550 |
347
Similar to 321 but with Niobium (2 x the amount of titanium) added as a stabiliser. Better transfer of stabilising addition (Nb) in 347 than in 321 during welding.
UK favours the use of 321 whereas USA favours 347.
Applications
Type 347 is mainly used where corrosion resistance and sustained operations at temperatures between 426° C. and 871° C. is of the utmost importance. It is also a superior grade for use on heavy welded objects, which cannot be re-annealed. It finds its principal applications in aircraft and missile engines, high temperature equipment in chemical industry, manifolds, furnace and blower parts, and etc.
Corrosion Resistance
Resistance to intergranular corrosion and carbide precipitation is excellent with this grade. Its general atmospheric corrosion resistance is good, being similar to that of Type 302.
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