AISI D2: High-Carbon High-Chromium Cold Work Tool Steel
ASTM A681 · Published: 2026-06-03 · Updated: July 2026
AISI D2 (1.55% C, 12% Cr, 0.8% Mo, 0.9% V) is the most widely used cold work tool steel — the standard grade for blanking dies, forming dies, shear blades, and thread rolling dies. It achieves 58-62 HRC after hardening with excellent wear...
AISI D2 (1.55% C, 12% Cr, 0.8% Mo, 0.9% V) is the most widely used cold work tool steel — the standard grade for blanking dies, forming dies, shear blades, and thread rolling dies. It achieves 58-62 HRC after hardening with excellent wear resistance from its high volume of chromium carbides.
Quick Facts
| Category | Tool Steel |
| Standard | ASTM A681 |
| Density | 7.70 g/cm³ |
| Yield Strength | 1,530-1,860 MPa (hardened) |
| Tensile Strength | 1,720-2,000 MPa |
Detailed Mechanical Properties
| Hardness | 58-62 HRC (hardened & tempered) |
| Elongation | 1-3% (hardened condition) |
Physical Properties
| Melting Point | 1421°C |
| Thermal Conductivity | 20.0 W/m·K at 20°C |
| Density | 7.70 g/cm³ |
Global Equivalents & Cross-Reference
Heat Treatment & Processing
| Austenitizing | 1000-1040°C, soak 20-30 min (air hardening — D2 is an air-hardening tool steel) |
| Quenching | Air cool or pressurized gas quench (oil quench risks cracking due to high hardenability) |
| Tempering | 150-540°C depending on desired hardness; double temper recommended for retained austenite transformation |
| Annealing | 840-870°C, furnace cool at 10-20°C/h to 540°C, then air cool |
Welding & Fabrication
| Preheat | 400-500°C; maintain throughout welding — D2 has very high carbon (1.5%) and chromium (12%) = extreme hardenability = extreme crack sensitivity |
| Filler Metal | D2 filler or E312 stainless (for repair welding where hardness match is not critical) |
| Pwht | Anneal immediately after welding, then re-harden and temper to specification |
| Weldability Rating | Poor — D2 is not recommended for welding in service applications; welding is for repair only and requires full heat treatment cycle afterward |
Related Materials
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Frequently Asked Questions
How does D2 compare to O1 tool steel?
D2 has approximately 2-3× the wear resistance of O1 due to its 12% chromium carbide content, but is more difficult to machine and grind. O1 is an oil-hardening grade with better toughness and machinability. Choose D2 for long-run stamping and blanking dies; choose O1 for lower-volume tooling requiring frequent modification.
References & International Standards
- ASTM International. Standard Specifications for Steel & Metal Alloys. astm.org
- International Organization for Standardization (ISO). Metallic Materials — Cross-Reference Database. iso.org
- American Iron and Steel Institute (AISI). Steel Grade Designations & Equivalents. steel.org
- European Committee for Standardization (CEN). EN Steel Standards & Numbering System. cencenelec.eu