Columbium and tantalum have been added to 347 to form columbium carbide in preference to chromium carbide in the sensitization range. Columbium stabilization is desired because its carbides are better retained in welds. It also delays becoming sensitized during exposures to temperatures in the sensitization range. Type 347 does require more care due to the presence of columbium.
This grade has similar applications to Type 321, others include aircraft exhausts and manifolds, fire walls, extended welding of heavy sections for high temperature use, heavy wall welded equipment and heat exchangers.