Materials
440C stainless steel
A high-carbon, high-chromium stainless — among the hardest of the classic stainless grades — prized for scissors and shears.
A short history
The 440 series (440A, 440B, 440C) are high-carbon martensitic stainless steels defined in the American AISI system. 440C has the most carbon of the three and has long been used for bearings, knives and professional hair shears. Steel mills in Japan produce it under the equivalent designation SUS440C.
Composition
- Chromium
- 16–18%
- Carbon
- 0.95–1.20%
- Molybdenum
- ≤ 0.75%
- Structure
- Martensitic, with hard chromium carbides
Steel counts as stainless when it carries at least about 10.5% chromium (the threshold used in the European standard EN 10088). The chromium reacts with oxygen to form an extremely thin, self-repairing chromium-oxide film on the surface. This passive layer is what stops rust. It re-forms on its own after light scratching, provided the surface is clean and exposed to air.
How it's hardened and tempered
Martensitic stainless steels are hardened in three steps: austenitizing (heating to roughly 950–1,050 °C so carbon dissolves into the steel), quenching (rapid cooling, which locks the structure into hard martensite) and tempering (reheating to a lower temperature to trade a little hardness for toughness, so edges and tips don't chip or snap). Exact temperatures depend on the grade and the part. The high carbon forms hard chromium carbides in the steel, which is why 440C resists wear so well once hardened.
Why it lasts
- Very hard after heat treatment, so a convex shear edge stays sharp through more cuts between sharpenings.
- Wear resistant because of the carbides in the steel.
- Higher chromium than 420 for good corrosion resistance in a wet salon environment.
Care tips
- Wipe hair and moisture off after every client; dry the pivot area.
- Oil the pivot daily with shear oil and keep the tension correctly set.
- Never drop shears — hard steel is more brittle, and a drop can chip or misalign the blades.
- Have edges professionally sharpened (ours are sharpened free for life).
Compared with cheaper alternatives
| Feature | 440C stainless | 420 stainless | Unbranded "stainless" |
|---|---|---|---|
| Hardness potential | Very high | High | Unknown |
| Edge life | Longest of the three | Good | Unpredictable |
| Corrosion resistance | Good (16–18% Cr) | Good (12–14% Cr) | Unknown |
Where we use it
We list 440C as the shear steel grade; ask us to confirm the grade and hardness for a specific batch.
Every piece is backed by our Lifetime Warranty*.