Low Carbon Grade (L)

A stainless grade with carbon capped at 0.030% — 304L, 316L, 317L — so welded joints resist intergranular corrosion without post-weld heat treatment.

When the L matters

If the equipment is welded and will be left as-welded, specify the L grade. The carbon cap starves the grain boundaries of the carbon needed to form chromium carbides, so the heat affected zone keeps its corrosion resistance.

The trade-off

Lower carbon means slightly lower strength — 200 MPa minimum yield for 304L against 215 MPa for 304. For code work above about 525 °C the H grades go the other way, raising carbon deliberately for creep strength.

Related terms

Where this applies

Austenitic Stainless Steel Plate

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