JIS G4304/4312 SUS 304L steel is a low-carbon austenitic stainless steel that is widely used in various industrial sectors due to its excellent corrosion resistance, processability, and weldability.
1. Chemical and Petrochemical Industry
Application Scenarios: Manufacturing equipment such as storage tanks, pipelines, pump valves, and reactors.
Advantages:
Corrosion Resistance: It demonstrates stable performance in corrosive media containing chloride ions, sulfuric acid, acetic acid, etc., with an annual corrosion rate of less than 0.002 mm (3% sodium chloride solution immersion test).
Intergranular Corrosion Resistance: With a carbon content of ≤0.03%, the precipitation of chromium carbides in the heat-affected zone after welding is significantly reduced, and the susceptibility to intergranular corrosion is approximately 40% lower than that of standard 304.
High-Temperature Performance: It can resist intergranular corrosion for up to 480 hours at a sensitization temperature of 650°C (sulfuric acid-copper sulfate solution test).
Case Study: The pipelines in the auxiliary system of a nuclear power plant, made of 304L, showed an average corrosion thinning of only 3% of the original wall thickness after 15 years of service.
2. Food and Pharmaceutical Industry
Application Scenarios: Food processing equipment (e.g., dairy fermentation tanks, beer fermentation vessels) and pharmaceutical equipment (e.g., sterile pipelines, pharmaceutical containers).
Advantages:
Hygienic Properties: It is non-toxic and non-adsorptive, meeting food-grade standards.
Surface Treatment: After electrolytic polishing, the surface roughness Ra is ≤0.4 μm, reducing microbial adhesion by 90%.
Welding Performance: The pass rate of automatic orbital welds reaches 99.8% (sterile pipeline systems in the pharmaceutical industry), far exceeding the 92% of ordinary 304.
Case Study: An international beverage company adopted 304L for the inner walls of its aseptic filling lines to ensure product safety.
3. Marine and Coastal Engineering
Application Scenarios: Seawater desalination equipment, coastal chemical pipelines, and ship components.
Advantages:
Chloride Ion Corrosion Resistance: In a hot water environment (80°C) with a chloride ion concentration of up to 200 ppm, the pitting potential is approximately 150 mV higher than that of ordinary 304.
Long-Term Stability: A seawater desalination project using 304L significantly extended the service life of the equipment.
