AISI H13 (SKD61): Hot Work Tool Steel for Die Casting and Forging Dies
ASTM A681 · Published: 2026-06-03 · Updated: July 2026
AISI H13 is the most widely used hot work tool steel — the standard material for aluminum die casting dies, extrusion tooling, and forging dies. Its 5% chromium and 1.3% molybdenum content provides high hot hardness, resistance to thermal fatigue...
AISI H13 is the most widely used hot work tool steel — the standard material for aluminum die casting dies, extrusion tooling, and forging dies. Its 5% chromium and 1.3% molybdenum content provides high hot hardness, resistance to thermal fatigue cracking (heat checking), and good toughness at elevated temperatures.
Quick Facts
| Category | Tool Steel |
| Standard | ASTM A681 |
| Density | 7.80 g/cm³ |
| Yield Strength | 1,350-1,580 MPa |
| Tensile Strength | 1,520-1,780 MPa |
Global Equivalents & Cross-Reference
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Frequently Asked Questions
What causes heat checking in H13 dies and how can it be minimized?
Heat checking is caused by cyclic thermal stress — the die surface rapidly heats when molten aluminum contacts it, then cools during spray release. Differential thermal expansion creates tensile stress at the surface that eventually forms a crack network. Mitigation: (1) maintain uniform die preheat to 200-250°C, (2) use premium H13 (ESR/VAR remelted) with lower sulfur and inclusion content, (3) nitride the die surface to introduce compressive residual stress.
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