AISI 420 Martensitic Stainless Steel: Hardenable Cutlery Grade
ASTM A276 · Published: 2026-06-01 · Updated: 2026-06-02
AISI 420 is a higher-carbon martensitic stainless steel (0.15% C min for 420, 0.30-0.40% C for 420HC) that can be hardened to 50-55 HRC—making it the standard cutlery-grade stainless steel. It provides the best combination of hardness and...
AISI 420 is a higher-carbon martensitic stainless steel (0.15% C min for 420, 0.30-0.40% C for 420HC) that can be hardened to 50-55 HRC—making it the standard cutlery-grade stainless steel. It provides the best combination of hardness and corrosion resistance among the standard martensitic grades (410/420/440). Used for kitchen knives, surgical instruments, shear blades, valve seats, and plastic injection molds requiring corrosion resistance with high hardness. The higher carbon content compared to 410 provides greater hardness capability at some sacrifice in corrosion resistance and toughness. 420HC (high carbon variant at 0.45% C) is the standard blade steel for Buck Knives and Leatherman multi-tools, hardened to 56-58 HRC.
Quick Facts
| Category | Stainless Steel |
| Standard | ASTM A276 |
| Density | 7.70 g/cm³ |
| Yield Strength | 345 MPa (50 ksi) annealed; 1,310 MPa (190 ksi) hardened |
| Tensile Strength | 655 MPa (95 ksi) annealed; 1,720 MPa (249 ksi) hardened |
Global Equivalents & Cross-Reference
| Alternative Standard / Grade | Action |
|---|---|
| EN 1.4021 | Compare |
| X20Cr13 | Compare |
| SUS420J1 | Compare |
| 20Cr13 | Compare |
| AISI 420 | Compare |
Related Materials
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Frequently Asked Questions
What is the difference between 420 and 440C stainless?
440C has significantly higher carbon (0.95-1.20%) and chromium (16-18%) for maximum hardness (58-60 HRC) and wear resistance among hardenable stainless steels. It is the standard for high-end bearing balls and races, premium knife blades, and valve components. 440C has lower corrosion resistance than 420 due to chromium being tied up in carbides. 420 provides a better balance for general cutlery and surgical instruments; 440C is chosen when maximum hardness and wear resistance are required.
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