The Difference Between 304 and 316 Stainless Steel

1. Differences in Chemical Composition

304 stainless steel contains approximately 18% chromium and 8% nickel. It is a typical 18-8 austenitic stainless steel with basic corrosion resistance, making it suitable for general atmospheric and mildly corrosive environments.

316 stainless steel sheet adds 2% to 3% molybdenum (Mo) to the 304 composition, effectively enhancing its resistance to intergranular corrosion.

2. Differences in Corrosion Resistance

304:

Suitable for air, fresh water, general food applications, and indoor environments;

Not resistant to seawater, brine, chloride ions, or chemical salt spray; prone to pitting corrosion in chloride-ion environments.

316:

Molybdenum specifically resists chloride-ion corrosion;

Resistant to seawater, brine, humid coastal environments, and chemical liquids; its resistance to pitting corrosion is far superior to that of 304.

3. Performance Differences

1) Mechanical Properties

The tensile strength and yield strength of both grades are essentially equivalent, and both can meet the strength requirements for most structural and machined components.

2) High-Temperature Resistance

Their performance at room temperature is similar; 316 has slightly better high-temperature strength.

3) Machining and Welding

Both are easy to weld; 316 is slightly more difficult to machine.

4) Magnetism

Both are austenitic stainless steels and are essentially non-magnetic, though they may exhibit slight magnetism after cold working.

5) Price

316 > 304; the cost of nickel and molybdenum is higher.

4. Differences in Application Scenarios

304 Stainless Steel

Offers high cost-effectiveness and is primarily used for interior decoration, general mechanical equipment, household appliances, and freshwater piping systems:

1) Household kitchenware, drinking cups, cutlery, and thermoses;

2) Indoor water pipes, hardware, and appliance casings;

3) General food processing equipment, excluding saltwater or coastal environments.

316 Stainless Steel

Suitable for outdoor projects, marine equipment, chemical reaction vessels, medical devices, and high-humidity or salt-fog environments where high corrosion resistance is required:

1) Coastal equipment, seawater, and swimming pool equipment;

2) Medical devices and pharmaceutical equipment;

3) Chemical processing, seafood processing, and containers for saline liquids;

4) High-end baby and maternity water cups.