Description
Global Standards & Designations
| Region |
Standard |
Grade |
| USA |
ASTM A240 |
UNS S42000 |
| Europe |
EN 1.4021 |
X20Cr13 |
| Japan |
JIS SUS420J1 |
- |
| China |
GB 20Cr13 |
- |
Chemical Composition (Weight %)
| Element |
Cr |
C |
Mn |
Si |
P |
S |
Fe |
| Content |
12–14% |
0.15–0.40% |
≤1.0% |
≤1.0% |
≤0.040% |
≤0.030% |
Balance |
Key Properties
Hardness & Wear Resistance: Achieves 50–55 HRC after heat treatment, outperforming 410 in edge retention.
Moderate Corrosion Resistance: Resists organic acids, steam, and mild chemicals (not suitable for marine use).
Machinability: Pre-hardened strips (28–32 HRC) allow efficient CNC or stamping operations.
Heat Treatability: Oil or air quenching enables tailored hardness-toughness balance.
Mechanical Properties
| Condition |
Tensile Strength |
Yield Strength |
Elongation |
Hardness |
| Annealed |
655 MPa |
345 MPa |
20% |
200 HB |
| Hardened & Tempered |
1.720 MPa |
1.380 MPa |
8% |
50–55 HRC |
Competitive Advantages
Surgical-Grade Precision: Meets ASTM F899 for reusable scalpels and dental tools.
Cost vs. Performance: 30% lower cost than 440C with 85% of its edge retention.
Surface Flexibility: Available in polished (Ra ≤0.4 µm), bead-blasted, or TiN-coated finishes.
Plastic Molding Mastery: Resists abrasive glass-filled polymers without galling.
Industry Applications
Medical: Surgical forceps, biopsy punches, orthopedic rasps.
Food Processing: Meat dicer blades, dough cutter rollers, packaging knives.
Defense: Firearm bolts, bayonet components, tactical knife blanks.
Industrial: Textile cutter bars, printing press blades, bearing races.
Consumer: Razor blades, garden shear plates, luxury watch cases.
Heat Treatment Guidelines
Annealing: Heat to 840–900°C, slow cool at 25°C/hour to 600°C.
Hardening: Quench from 980–1.050°C in oil/air, then temper at 150–400°C (higher temps for toughness).
Stress Relieving: 250–300°C for 1–2 hours post-machining.
Frequently Asked Questions
Q1: How does 420 compare to 440C?
A1: 440C has higher carbon (0.95–1.20%) and chromium (16–18%) for extreme edge retention (58–62 HRC) but is less economical for bulk production.
Q2: Can 420 strips be welded?
A2: Yes, but preheat to 200–300°C and use AWS ER410 filler. Post-weld annealing is recommended to restore corrosion resistance.
Q3: Is 420 suitable for dishwasher use?
A3: Limited. Prolonged exposure to chlorinated detergents may cause pitting—passivate with nitric acid for improved performance.
Q4: What’s the optimal finish for FDA compliance?
A4: Electropolished (Ra ≤0.5 µm) or BA finish meets FDA 21 CFR 175.300 for indirect food contact.
Q5: How to prevent rust in humid environments?
A5: Apply silicone-based dry-film lubricants or specify 420F (free-machining variant with added sulfur).
