Explaining The Differences Between Stainless Steel 304 and 316
Differences between stainless steel 304 VS. 316 are subtle, but important depending on the application. Outwardly, 304 stainless steel and 316 stainless steel look very similar. Both are non-magnetic, austenitic, and non-hardenable through heat treatment. Each of these stainless steel grades will resists corrosion, are quite durable, and are easily formed and fabricated. The difference in their structure is primarily the addition of molybdenum to 316. Molybdenum further increases the corrosion resistance of the material, making it ideal for more acidic environments.
| 304 | 316 | ||||
|---|---|---|---|---|---|
| Carbon | C | 0.08 max | Carbon | C | 0.08 max |
| Manganese | Mn | 2.00 max | Manganese | Mn | 2.00 max |
| Phosphorus | P | 0.045 max | Phosphorus | P | 0.045 max |
| Sulfur | S | 0.03 max | Sulfur | S | 0.30 max |
| Silicon | Si | 0.75 max | Silicon | Si | 0.75 max |
| Chromium | Cr | 18.00 - 20.00 | Chromium | Cr | 16.00 - 18.00 |
| Nickel | Ni | 8.00 - 12.00 | Nickel | Ni | 10.00 - 14.00 |
| Nitrogen | N | 0.10 max | Molybdenum | Mo | 2.00 - 3.00 max |
| Iron | Fe | Balance | Nitrogen | N | 0.10 max |
| Irion | Fe | Balance |
With its superior formability, 304 is the most common austenitic grade of stainless steel. All other grades are developed from the 18-8 base by adding alloying elements to provide special corrosion resistance or better weldability. Type 304 makes up over 60% of all the stainless steel made in the world today.
The wide usage of 304 stainless steel in food and beverage and pharmaceutical applications reflects the corrosion resistance qualities of these materials. These industries demand that materials do not release significant quantities of contaminants into the product. They must also be easily cleaned. For example, liquid blending and storage tanks are readily cleaned, providing proper hygiene in food prep as well as food and beverage handling. Commercial dishwashing detergents eliminate 97% of microorganisms adhering to stainless steel surfaces. Flavor and color are kept intact, with no impact from contact with the tank material. 304 is a great choice for kitchen applications including appliances, sinks, pots and pans and flatware.
304 is also used in heat exchangers, building facades, wheel covers, hose clamps, pressure vessels and other applications involving freshwater environments.
316 stainless steel, with its addition of 3% molybdenum, is considerably more resistant to corrosive environments than 304. This grade is more suitable for sea water environments and marine applications. Because of its greater resistance to oxidations, it’s also widely used in refining equipment, fasteners, pulp and paper processing equipment, and pharmaceutical processing equipment.
The molybdenum content also increases the grade strength at high temperatures making it appropriate for use in heat exchangers, jet engine parts, exhaust manifolds and other high-temp applications.
316 is often referred to as “surgical steel”. Resistance to acids and high tensile strength make 316 a popular choice for surgical instrumentation and implants. Its durability allows for intense sterilization required in medical devices.
When choosing between stainless grades 304 and 316, be sure you carefully consider the environment in which your product will be operating. Corrosion resistance is the #1 consideration, followed by the higher formability found in 304, or the need for strength and durability found in 316.
The technical data provided is for information only and not for design purposes. It is not warranted or guaranteed.