D2
D2 is a high-carbon, high-chromium tool steel that became one of the most widely used knife steels of the late 20th century, prized for its excellent wear resistance and a chromium content just high enough to earn it the nickname “semi-stainless.” It is air-hardening, which keeps distortion low, but its heavy carbide load makes it notably harder to grind and sharpen than most other knife steels.
D2 FAQ
Is D2 stainless steel?
Not quite. D2 sits right at the edge of the stainless threshold with 11.5-12% chromium, earning it the nickname “semi-stainless.” It resists rust better than plain tool steels but will still spot or stain without regular care, unlike true stainless steels.
What hardness does D2 reach?
Typically 58-64 Rc depending on temper, with 60-62 Rc common for knife use. See the heat treat details further down this page for the full recipe.
Is D2 hard to sharpen?
Yes, it is one of the more demanding steels in this database to sharpen due to its heavy carbide content. Diamond stones are strongly recommended. See the full grinding and sharpening guide.
How does D2 compare to CPM 154 or AEB-L?
D2 offers better edge retention than both, but is tougher, harder to grind, and less corrosion resistant than either. See the full breakdowns: D2 vs CPM 154 and D2 vs AEB-L.
Also known as: D2, AISI D2, 1.2379
Composition
| Carbon (C) | 1.50-1.55% |
| Chromium (Cr) | 11.50-12.00% |
| Molybdenum (Mo) | 0.75-0.90% |
| Vanadium (V) | 0.80-0.95% |
| Manganese (Mn) | 0.30-0.50% |
| Silicon (Si) | 0.25-0.40% |
Properties
| Property | Rating | Notes |
|---|---|---|
| Toughness | ★★☆☆☆ | The weak point of D2: its heavy carbide volume makes it more prone to chipping than most modern powder-metallurgy steels, and it has a reputation for being harder to sharpen back to a clean edge after damage. |
| Edge Retention | ★★★★☆ | Very good wear resistance thanks to a large volume of chromium and vanadium carbides, a big part of why it remained popular for decades before newer powder-metallurgy steels became common. |
| Corrosion Resistance | ★★☆☆☆ | Chromium sits right at the edge of the stainless threshold, giving it noticeably better rust resistance than plain tool steels, but it will still spot or stain without regular care, unlike true stainless steels. |
| Machinability / Grinding | ★★☆☆☆ | Hard on belts due to its heavy carbide load; grinds and sharpens more slowly than simpler carbon or basic stainless steels. |
Heat Treatment
Preheat at 450-500 C (842-932 F), equalize, then raise to a second preheat of 850-900 C (1560-1650 F). Austenitize at 1850-1900 F, holding 30-45 minutes for the first inch of thickness plus 15 minutes per additional inch. D2 is air-hardening, so quench in still air, which keeps distortion low. Temper between 300 and 500 F depending on the goal: 300-350 F favors maximum wear resistance (62-64 Rc), while 500-550 F gives a better balance of wear resistance and toughness (58-60 Rc).
Best Uses
A long-time favorite for hunting knives, kitchen knives, and production knives where strong wear resistance and low heat-treat distortion matter more than maximum toughness. Browse more entries in the Knife Steel Database, and see the Heat Treating Guide for the full stage-by-stage process.
Sources: Standard AISI D2 tool steel specification; Larrin Thomas, How to Heat Treat D2, PSF27, and CPM-D2, Knife Steel Nerds; Hudson Tool Steel D2 technical data.