Some of you are wondering which steel to choose from our CATS system, 316L or 304. It is not a difficult decision if you are clear about the water hardness in the geographical area where you are going to make the installation.

This comparison will help you to choose the one that suits you best for your work.

Definition

316L stainless steel and 304 stainless steel are two common variants of austenitic stainless steels, and although they share some similarities in their basic composition, they have significant differences in terms of properties and applications.

Chemical composition

• 316L: Contains a higher percentage of molybdenum (approximately 2-3%) compared to 304 stainless steel, which improves its corrosion resistance in aggressive environments.
• 304: Contains less molybdenum (generally less than 0.03%).

Corrosion resistance

• 316L: Offers superior corrosion resistance, especially in environments involving chlorides and other corrosive agents. It is best suited for marine and chemical applications.
• 304: Has good corrosion resistance in a wide variety of environments, but is not as resistant as 316L in the presence of chlorides.

Resistance to stress corrosion

316L: Has better resistance to stress corrosion cracking (stress corrosion cracking) than 304, making it more suitable for applications where structural integrity is critical.

304: Although it offers resistance to stress corrosion, it is not as robust as 316L in this respect.

Weldability

Both are readily weldable, but 316L may be more sensitive to pitting corrosion in heat-affected zones after welding. Heat treatment after welding is recommended to maintain corrosion resistance.

Applications

• 316L: Commonly used in more corrosive environments, such as chemical, marine, food processing and medical applications.
• 304: It is suitable for a wide range of applications, such as the manufacture of cookware, architectural components, medical equipment and storage tanks.

Cost

316L stainless steel tends to be more expensive than 304 due to the higher amount of molybdenum and other alloying elements.

High temperature resistance

Both maintain their strength at elevated temperatures, but 316L may be slightly more resistant to corrosion at high temperatures due to its higher molybdenum content.

In summary, the choice between 316L stainless steel and 304 stainless steel will depend on the specific conditions of the application. If corrosion resistance in aggressive environments is crucial, 316L may be the preferred choice. However, 304 is still an excellent choice for many applications and is less expensive.