About 347|Niobium (columbium)-stabilized austenitic stainless. Same concept as
321 but uses niobium instead of titanium to prevent intergranular corrosion during welding and high-temperature service. Preferred over 321 for applications above 1000°F because niobium carbides are more stable than titanium carbides at extreme temperatures. Used in jet engine components, chemical processing equipment, and high-temperature piping. Machines like
304 with similar challenges. Compare to 321 (titanium-stabilized, better below 1000°F) and
304L (low-carbon approach, simpler but not rated for continuous high-temperature service).
