SS321 vs SS347: High-Temperature Performance Comparison

Stabilizing Element:

SS321: Titanium (Ti) added to prevent chromium carbide formation.

SS347: Niobium (Nb) added for the same purpose.

Corrosion Resistance:

SS347: Superior in the 800-1500°F (427-816°C) range, especially in strong oxidizers, due to better carbide stabilization than 321.

SS321: Good but less resistant in prolonged exposure in that critical range.

Welding:

SS347: Niobium transfers better across high-temp welding arcs, making 347 the standard filler for 321.

SS321: Titanium doesn't transfer as well in the arc.

Thermal Cycling:

SS321: Excels in repeated heating/cooling cycles (thermal cycling).

Applications:

SS321: Excellent for aerospace (exhausts, bellows) and equipment with thermal cycling.

SS347: Preferred for high-temp environments needing maximum carbide resistance, often as filler or in corrosive high-temp conditions.