Stainless Steel 304/304L vs. 316/316L: The Role of Molybdenum in Corrosion Resistance
1. The 300 Series Baseline Stainless steel is defined by its Chromium content, which forms a protective “passive layer.”
- Grade 304/304L: The most common “18/8” stainless steel. It offers excellent corrosion resistance in fresh water and mild atmospheric conditions.
- Grade 316/316L: Known as “Marine Grade” stainless steel. It contains 2-3% Molybdenum (Mo), which significantly enhances its resistance to pitting and crevice corrosion.
2. What Does the “L” Stand For? The “L” denotes Low Carbon (max 0.03%). During welding, standard carbon grades (304/316) can suffer from “sensitization,” where carbon reacts with chromium at the weld zone, leading to intergranular corrosion. The “L” grades prevent this, making them essential for all welded PVF components.
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