ER316L vs. ER308L: Key Differences in Stainless Steel Welding Applications

ER316L and ER308L are both stainless steel filler metals commonly used in welding, but they have different applications and material compatibility due to their chemical compositions. Here's a comparison of the two:

1. Chemical Composition

• ER308L: Designed for welding 304 and 304L stainless steels. It contains lower carbon content to minimize carbide precipitation, which helps to prevent intergranular corrosion.
• ER316L: Contains added molybdenum (Mo), which improves corrosion resistance, especially against chlorides. It is designed for welding 316 and 316L stainless steels.

2. Corrosion Resistance

• ER308L: Offers good corrosion resistance in general environments, but it lacks the additional protection that molybdenum provides.
• ER316L: Provides superior corrosion resistance, particularly in harsh environments where the material will be exposed to chemicals, salts, or chlorides, such as in marine or chemical processing industries.

3. Applications

• ER308L: Commonly used in general-purpose welding of 304/304L stainless steels, which are often found in food-grade and industrial environments.
• ER316L: Preferred for applications that involve more aggressive environments, such as marine applications, chemical plants, or areas exposed to saltwater.

4. Strength and Ductility

• Both ER308L and ER316L offer similar mechanical properties, including tensile strength and ductility, though ER316L is generally preferred in environments where additional corrosion resistance is required due to the presence of molybdenum.

5. Welding Process

• Both can be used in TIG (GTAW) and MIG (GMAW) welding processes, and they perform similarly in terms of weldability, but material choice depends on the base metal and the environment in which the weld will be used.

Summary:

• ER308L: Used for general-purpose welding of 304/304L stainless steel in environments with lower corrosion risks.
• ER316L: Used for 316/316L stainless steel, offering enhanced corrosion resistance, particularly in chloride-containing environments such as marine or chemical processing applications.

The choice between ER308L and ER316L depends on the base metal being welded and the level of corrosion resistance required.