Blanking & forming dies
High-volume stamping dies for fiberglass, composites, hardened sheet steel. Where A2 wears too fast.
High-Cr cold-work tool steel · UNS T30402
D2 Tool Steel
High-chromium cold-work tool steel for maximum wear resistance. The 12% chromium content forms hard chromium carbides that punch above their weight against abrasive media — fiberglass, composites, hardened parts, and high-volume blanking. More wear-resistant than A2; more brittle in shock loading.
Hardness
60-62 HRC
Density
7.70 g/cc
Modulus
207 GPa
Mach. (ann.)
50 /100
When to use
Pick D2 when wear is the dominant failure mode.
D2’s 12% chromium and 1.5% carbon content create a microstructure dense with chromium carbide particles — hard ceramic-like inclusions distributed in the steel matrix. These carbides do the wear work. Against abrasive materials (fiberglass-reinforced plastic, hardened steel sheet, ceramic-filled composites, sandy slurries), D2 dies last 3–5× longer than A2 dies running the same parts.
The trade-off is impact toughness — D2 is more brittle than A2 at the same hardness. For shock-loaded tooling (drop forging, heavy stamping with potential misfeed), A2 or S7 is the safer choice. For pure wear under steady loading, D2 wins.
Strengths
Why dies run longer.
- Best wear resistance in cold-work tool steels12% Cr means dense carbide volume — abrasion resistance is exceptional.
- Air hardeningSame as A2 — minimal HT distortion. Through-hardens to 60+ HRC up to ~75 mm sections.
- Holds edgeExcellent edge retention against abrasive materials. Common substrate for high-end pocket knives.
- Some corrosion resistance12% Cr provides weak corrosion resistance — better than A2 in moderate environments.
- High compressive strength~3,000 MPa compressive — outstanding for stamping dies and cold-headed punches.
Trade-offs
Where A2 / S7 win.
- More brittle than A2Impact toughness ~1/2 of A2. Will chip under shock load.
- Lower machinabilityMach 50/100 in annealed condition — the carbides cut tools fast. Lots of carbide tooling consumption.
- Difficult to grindHard chromium carbides are abrasive even to grinding wheels. CBN preferred for production grinding.
- Harder to weldRepair welding requires preheat, post-weld stress relief, and skilled technique. Often re-make rather than repair.
- Cost premium~30% more than A2 by weight. Justified for genuine wear applications.
- Larger HT distortion than A2Higher carbide content creates more dimensional change. Tighter post-HT grinding stock allowance.
Specs
Mechanical, physical & chemical data.
Properties for D2 in standard hardened condition (austenitize 1010 °C, air-cool, temper 175–205 °C × 2 hr) — yielding 60-62 HRC. Higher temper produces lower hardness (down to 55 HRC at 540 °C tempering).
Mechanical
Properties
| Hardness (annealed) | ≤ 255 HB / B98 |
|---|---|
| Hardness (HT typical) | 60-62 HRC |
| Hardness (HT max) | 63-64 HRC |
| UTS (HT) | ~2000 MPa (290 ksi) |
| Yield strength (HT) | ~1900 MPa |
| Modulus of elasticity | 207 GPa |
| Charpy V-notch (60 HRC)Lower than A2 | 5 J |
| Compressive strength (HT) | 3000 MPa |
| Wear (CrC vol fraction) | ~14% |
Source: Crucible Industries datasheets. Compare A2 Charpy at 60 HRC: 13 J. D2's carbide content is the wear strength but reduces toughness.
Physical & thermal
At room temperature
| Density | 7.70 g/cc (0.278 lb/in³) |
|---|---|
| Specific heat | 0.460 J/g·°C |
| Thermal conductivity | 20 W/m·K |
| CTE (20–100 °C) | 10.4 µm/m·°C |
| Austenitize temp | 1010 – 1040 °C |
| Critical temp (Ac1) | 810 °C |
| Quench medium | Air (preferred) or oil |
| Magnetic | Ferromagnetic |
Higher austenitizing temperature than A2 — required to dissolve some chromium carbides into solid solution before air quenching.
Composition
Chemistry, weight %
| Carbon (C) | 1.40 – 1.60 |
|---|---|
| Chromium (Cr) | 11.0 – 13.0 |
| Molybdenum (Mo) | 0.70 – 1.20 |
| Vanadium (V) | 1.10 max |
| Manganese (Mn) | 0.60 max |
| Silicon (Si) | 0.60 max |
| Phosphorus (P) | 0.030 max |
| Sulfur (S) | 0.030 max |
| Iron (Fe) | balance |
Compare to A2's 5% Cr — D2 has more than twice as much. The chromium forms hard CrC carbides that drive the wear performance.
Specifications
Common purchase specs.
ASTM A681
Tool steels — alloy
AISI D2 / SAE D2
Standard designation
UNS T30402
Unified numbering
FED-QQ-T-570
Federal tool steel spec
DIN X153CrMoV12 / 1.2379
European equivalent
JIS SKD11
Japanese equivalent
Machining
Machining considerations.
Always machine annealed. Carbide-rich microstructure abrades tooling — plan for higher tool consumption than A2. Hardened D2 is grind-only (CBN) or wire-EDM territory.
Cutting speed (annealed)
230–330 SFM carbide milling, 330–490 SFM carbide turning (annealed; Uddeholm Sverker 21 data). Slower than A2 — carbides resist cutting.
Feed rate
Aggressive constant feed. Annealed D2 cuts steadily but with tool wear.
Tooling
Coated carbide (TiAlN) — replace before significant wear. CBN inserts for hardened material.
Coolant
Flood. High-pressure helps chip evacuation and tool life.
Stock allowance
Leave more for HT than A2 — 0.010-0.030″ on critical surfaces. Distortion is real.
Wire EDM after HT
Standard finish operation for hardened D2. Sharp internal corners and complex profiles done EDM.
Stress-relieve before HT
Critical for D2 — its high carbide content amplifies any pre-HT stress. ~675 °C for 1 hour.
Grinding
CBN wheels for production. Aluminum oxide works but wears fast against the carbide content.
Applications
Where D2 shows up.
Punches & abrasive tooling
Cold-heading dies, ceramic-filled material handling, paper trim dies. Carbide content is the wear advantage.
High-end knife steel
Pocket and culinary knives. The carbide structure holds an edge against repeated cutting of abrasive materials.
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