Differences in Corrosion Resistance Between 316 and 304 Stainless Steel

316 stainless steel contains molybdenum (2.0-3.0%), which gives it superior corrosion resistance compared to 304 stainless steel in various environments.

For example, in saline environments such as coastal structures or seawater aquaculture equipment, 304 stainless steel may develop rust spots and corrosion pits after prolonged exposure to high-concentration saltwater due to chloride ion attack. In contrast, 316 stainless steel, with its molybdenum content, resists chloride-induced corrosion more effectively, maintaining better integrity in high-salt conditions.

In chemical processing environments where exposure to acidic or alkaline substances occurs, 304 stainless steel may show insufficient resistance to strong acids (e.g., concentrated sulfuric or hydrochloric acid), leading to chemical corrosion. However, 316 stainless steel's molybdenum significantly enhances its resistance to reducing media, performing much better in such corrosive chemical environments.

For certain foods and beverages—such as carbonated drinks, milk, and coffee—which contain acidic or reactive components, 304 stainless steel tableware may gradually lose its luster and show signs of corrosion after prolonged contact. In comparison, 316 stainless steel tableware resists such corrosive effects more effectively, maintaining both appearance and functionality.

In summary, 316 stainless steel is the preferred choice in environments demanding high corrosion resistance, while 304 stainless steel is more suitable for general, less corrosive applications.

Differences in Mechanical Properties

304 and 316 stainless steels also differ in mechanical properties. 304 stainless steel has slightly higher strength and hardness than 316, making it more suitable for applications requiring pressure resistance and wear resistance. For instance, in architectural decoration, 304 stainless steel structural components can meet basic mechanical requirements for support and fixation without deformation issues.

On the other hand, 316 stainless steel exhibits better ductility and tensile strength, making it less prone to cracking under bending or stretching forces. This makes it ideal for applications requiring complex shaping, such as medical instruments or precision components. Additionally, 316 stainless steel maintains better stability in high-temperature environments (e.g., industrial furnaces or heat exchangers), resisting softening and strength degradation, whereas 304 stainless steel performs slightly worse under prolonged high-temperature exposure.