What's the Difference Between Grade 304 and 304L …
In grade 304 stainless steel, the maximum carbon content is set at 0.08%, whereas grade 304L stainless steel has a maximum carbon content of 0.03%. This is why the "L" in 304L can be interpreted as meaning extra-low carbon. This difference of 0.05% carbon content produces a slight, but marked, difference in the performances of the two alloys.