Choosing the right stainless steel grade — and matching the correct filler — protects corrosion resistance and weld integrity. In short: 304 is the general-purpose grade, 316 adds molybdenum for superior corrosion resistance in marine and chemical environments, 304L is the low-carbon version preferred for welded fabrications, and duplex offers significantly higher strength and stress-corrosion resistance for demanding applications.
This guide compares the stainless grades welders most often have to choose between. For the matching filler metals, see our MIG and TIG filler wire comparisons.
304 vs 316 stainless steel
304 stainless steel is the most commonly used grade for general engineering, food equipment and architectural applications. 316 stainless steel contains molybdenum, providing superior corrosion resistance in marine, chemical and coastal environments.
Choose 316 where increased corrosion resistance is required, particularly in aggressive service conditions.
304L vs 304 stainless steel
304L is the low-carbon version of 304 stainless steel. The reduced carbon content lowers the risk of carbide precipitation during welding, helping maintain corrosion resistance in the heat-affected zone.
For welded fabrications, 304L is generally preferred over standard 304.
316 vs duplex stainless steel
316 stainless steel offers excellent corrosion resistance for many industrial applications. Duplex stainless steel provides significantly higher strength together with improved resistance to stress corrosion cracking, making it suitable for offshore, marine and chemical processing environments.
The choice depends on both the operating environment and mechanical requirements.
Match the grade to the service — and the filler to the grade
The grade determines the corrosion resistance and strength your fabrication needs; the filler metal then has to match it to preserve those properties through the weld. Getting both right first time avoids corrosion problems and cracking in service.
For filler matching see our MIG and TIG filler wire comparisons and our weld cracking guide, or contact the Weldability SIF technical team for advice.