440C

440C is one of the most well-known classic blade steels and served for decades as the benchmark for stainless knives. Here are the key facts:

Origin: 440C belongs to the American 440 steel series (440A, 440B, 440C) and is its hardest, highest-carbon variant. It is best known as the steel behind the legendary Buck 110 folding knife, made from 440C until 1981, before the manufacturer switched to a different steel.

Composition: 440C consists of the following main elements:
Carbon (C): approx. 0.95–1.20%
Chromium (Cr): approx. 16–18%
Molybdenum (Mo): approx. 0.75%
Manganese (Mn): approx. 1.0%
Silicon (Si): approx. 1.0%
Phosphorus (P): ca. 0,04 %
Sulphur (S): ca. 0,03 %

Unlike many modern knife steels, 440C is conventionally melted rather than produced via powder metallurgy (CPM), resulting in coarser chromium carbides than in steels like MagnaCut or S30V.

Hardness: typical range 58–60 HRC.

Edge Retention: 440C traditionally serves as the knife industry's reference steel — CATRA edge-retention figures for many modern super steels (e.g. S30V, S35VN, S45VN, M390) are still published as a percentage relative to 440C = 100%. Against modern powder steels like S30V or MagnaCut, 440C clearly falls behind; against the similarly conventionally melted VG-10, however, CATRA testing by Knife Steel Nerds puts it on a comparable, sometimes even slightly better level.

Corrosion Resistance: solid but moderate — good in dry to mild environments, though it falls short of more corrosion-resistant blade steels like H1, LC200N, or MagnaCut.

Practical Takeaway: Compared to modern powder steels like S30V or MagnaCut, 440C holds an edge for a shorter time, but sharpens more easily and takes a mirror polish. As a proven, widely available steel, it remains common in pocketknives, diving, and outdoor knives.