Description
Core Differentiation vs. Competing Grades
| Feature |
420 Plate |
410 |
440C |
| Hardness Post-Treatment |
50–56 HRC (oil quenched) |
40–45 HRC |
58–62 HRC |
| Corrosion Resistance |
Moderate (resists water, steam, mild acids) |
Low |
High (but brittle) |
| Cost per Ton (3mm) |
$3.800 (annealed) |
$3.200 |
$6.500 |
| Machinability |
Good in annealed state (75% vs. 304) |
Excellent |
Poor |
Key Properties & Chemistry
International Designations
EN: 1.4021
ASTM: AISI 420
China GB: 4Cr13
JIS: SUS 420J1
Chemical Composition
| Element |
Range (%) |
Role |
| Cr |
12.0–14.0 |
Corrosion resistance, hardenability |
| C |
0.15–0.40 |
Carbide formation, edge retention |
| Mn |
≤1.0 |
Deoxidation, machinability |
| Si |
≤1.0 |
Strength at high temps |
Performance Highlights
Heat Treatment Versatility
Achieve target hardness via:
Annealed: 85 HRB (easy to machine)
Quenched & Tempered: 50–56 HRC (optimal for blades)
Controlled Corrosion
Withstands 720-hour salt spray (ASTM B117) without pitting in dry environments.
Precision Grinding Compatibility
Surface finish ≤0.2 µm Ra achievable for medical tools.
Mechanical Properties
| Condition |
Tensile Strength |
Yield Strength |
Elongation |
Hardness |
| Annealed |
650–850 MPa |
345 MPa |
25% |
85 HRB |
| Hardened & Tempered |
1.600–2.000 MPa |
1.200 MPa |
5–10% |
50–56 HRC |
Industry-Specific Solutions
1. Medical & Dental
Scalpel blades | Orthodontic pliers | Bone saws
2. Food Processing
Meat dicers | Bakery cutting molds | Canning blades
3. General Manufacturing
Textile cutter bars | Plastic extrusion dies | Printer blades
4. Consumer Goods
High-end kitchen knives | Scissors | Safety razor heads
Real-World Validation
Swiss Surgical Tools Ltd.: “420 plates reduced our blade resharpening cycles by 70% vs. 440C.”
Tokyo Cutlery Co.: “No rust spots after 2 years in commercial kitchens with weekly sanitization.”
Houston Oilfield Gear: “420 wear plates outlasted carbon steel by 3x in valve components.”
Fabrication FAQs
Q: Optimal heat treatment protocol for knife-making?
A: Heat to 980–1.040°C → Oil quench → Temper at 150–370°C (lower temps = higher hardness).
Q: Can 420 be used in marine environments?
A: Not recommended for submerged parts; use 316L or 2205 for saltwater exposure.
Q: Best welding method for repaired tools?
A: Laser welding with ER420 filler; keep heat input <1.5 kJ/cm to avoid cracking.
Q: Lead time for ASTM A240 certified plates?
A: 7–10 days for EU stock (2–50mm thickness) | 14 days for custom medical-grade polishing.
