When choosing stainless steel that must withstand corrosive environments, austenitic stainless steel is typically used. Austenitic Stainless Steel has excellent mechanical properties, the high amounts of nickel and chromium in austenitic stainless steels also provide outstanding corrosion resistance. Additionally, many austenitic stainless steels are formable and easily weldable. SS 304 and SS 316 are the two of the more commonly used grades of austenitic stainless steel. This blog will examine the difference between stainless steel 304 and stainless steel 316, to help you determine which grade is right for your project.
Grade 304 stainless steel
304 stainless steel is generally regarded as the most common austenitic stainless steel. It contains high nickel content that is typically between 8 to 10.5 percent by weight and a high amount of chromium at approximately 18 to 20 percent by weight. Other major alloying elements include carbon, manganese, and silicon. The remainder of the chemical composition is mainly iron.
Stainless Steel 304 has excellent corrosion resistance because of the high amounts of nickel and chromium. Common applications of stainless steel 304 include:
- Appliances such as refrigerators and dishwashers
- Commercial food processing equipment
- Heat exchangers
- Structures in environments that would corrode standard carbon steel.
316 Stainless Steel
Grade 316 stainless steel has high amounts of chromium and nickel, similar to 304. SS 316 also contains silicon, manganese, and carbon, with the majority of the composition being iron. A major difference between stainless steel 304 and stainless steel 316 is the chemical composition, with Grade 316 containing a significant amount of molybdenum; typically 2 to 3 percent by weight whereas only trace amounts of molybdenum are found in 304. Grade 316 possesses increased corrosion resistance due to higher molybdenum content.
When selecting austenitic stainless steel for marine applications Stainless Steel 316 is often considered one of the most suitable choices. Other common applications of 316 stainless steel include:
- Chemical processing and storage equipment.
- Refinery equipment
- Medical devices
- Marine environments, especially those with chlorides present
Which Should You Use: Grade 304 or Grade 316?
Situations where 304 stainless steel may be the better choice:
- If the application requires excellent formability, the higher molybdenum content in Grade 316 can have adverse effects on formability and hence SS 304 grade may be used.
- The application has cost concerns. Grade 304 is typically more affordable than Grade 316.
Situations where 316 stainless steel may be the better choice:
- If the environment includes a high amount of corrosive elements.
- If the material will be placed underwater or be exposed to water consistently.
- In applications where greater strength and hardness are required SS 316 grade should be used.
Both these grades are available in various forms like Stainless Steel 304 Pipes, Stainless Steel 304 Plate, Stainless Steel 316 Pipes, Stainless Steel 316 Plates, etc. Both the grades are visibly same and very difficult to differentiate due to lack of visible difference between two identical pieces of different grades hence one should ask the Stainless Steel 304 Pipes Supplier to provide them material test report (MTR) of the actual material to validate it as being 304 or 316.