Is SUS304 stainless steel corrosion resistant?

SUS304 is an austenitic stainless steel in the Japanese standard (JIS), corresponding to the American ASTM 304 (UNS S30400).

Corrosion resistance of SUS304 stainless steel:
SUS304 stainless steel chemical composition advantages: 18-20% Cr: forms a dense oxide film (Cr₂O₃) to resist oxidative corrosion, 8-10.5% Ni: stabilizes the austenite structure and improves acid resistance.
SUS304 stainless steel application
Food/medical equipment: storage tanks, pipelines, conveyor belts (surface polishing/passivation required).
Architectural decoration: curtain walls, railings (avoid coastal high-salt environments).
Home appliances: sinks, oven liner (avoid long-term contact with acidic detergents).

SUS304 stainless steel intergranular corrosion risk:
High carbon content (≤0.07%): Cr carbides are easily precipitated during welding or long-term high temperature (400-850℃), resulting in Cr depletion at the grain boundary and corrosion.
Countermeasures: Annealing is required after welding (≥1050℃ solution quenching), or low-carbon SUS304L (carbon ≤0.03%) is used instead.
Chloride environment: Weak pitting resistance: pitting is prone to occur when in contact with salt water, seawater, and bleach.
If heated at 600°C to 800°C for about 10 minutes or longer, the corrosion resistance of SUS304 stainless steel will decrease.

SUS304 stainless steel corrosion resistant pipe

SUS304 stainless steel has good corrosion resistance in conventional environments (such as atmosphere, fresh water, and weakly acidic media), but the following points should be noted:
Annealing is required after welding to avoid intergranular corrosion;
Avoid long-term contact with chloride-containing environments (such as seawater and salt water);
Food-grade applications require surface polishing or passivation.
If used in high-corrosion scenarios (such as chemical and marine equipment), it is recommended to give priority to SUS316L or higher corrosion-resistant materials.