What is 420 Stainless Steel?
May 30, 2025
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420 stainless steel (AISI 420).pdf
What is 420 Stainless Steel?
420 stainless steel (AISI 420) is a hardenable martensitic stainless steel with a minimum chromium content of 12%. It offers high strength, good polishability, and can achieve very high hardness (up to ~50 HRC) after heat treatment.
It is magnetic in all conditions and used in applications where high wear resistance is more critical than corrosion resistance.
Equivalent Grades of 420 Stainless Steel
| Standard | Equivalent Grade |
|---|---|
| EN/DIN | EN 1.4021 (X20Cr13) |
| JIS | SUS420J1 / SUS420J2 |
| UNS | S42000 |
| GB (China) | 2Cr13 |
Note: SUS420J1 contains less carbon than SUS420J2, with J2 offering higher hardness after heat treatment.
Chemical Composition of 420 Stainless Steel (Typical)
| Element | Content (%) |
|---|---|
| C | 0.15–0.40 |
| Cr | 12.0–14.0 |
| Mn | ≤1.00 |
| Si | ≤1.00 |
| P | ≤0.04 |
| S | ≤0.03 |
High carbon content improves hardenability, but also reduces corrosion resistance compared to austenitic grades like 304 and 316.
Mechanical Properties of 420 Stainless Steel
After hardening and tempering:
| Property | Typical Value |
|---|---|
| Tensile Strength | 700–1000 MPa |
| Yield Strength | ~500 MPa |
| Hardness | Up to 50 HRC |
| Elongation | ~15% |
| Magnetic | Yes (fully magnetic) |
Which is Better: 316 vs. 420 Stainless Steel?
| Feature | 316 (Austenitic) | 420 (Martensitic) |
|---|---|---|
| Corrosion Resistance | Excellent (chloride-resistant) | Moderate |
| Hardness | Soft (non-hardenable) | Hardenable to HRC 50+ |
| Toughness | High | Moderate |
| Magnetic | Non-magnetic | Magnetic |
| Cost | Higher | Lower |
👉 Use 316 in marine, medical, or chemical environments. Use 420 in cutting tools, mechanical parts, or applications requiring wear resistance.
Which is Better: 304 vs. 420 Stainless Steel?
| Feature | 304 (Austenitic) | 420 (Martensitic) |
|---|---|---|
| Corrosion Resistance | Good (general purpose) | Lower |
| Hardness | Not hardenable | Hardenable |
| Weldability | Excellent | Limited |
| Applications | Kitchenware, tanks | Knives, tools |
Which is Better: 440 vs. 420 Stainless Steel?
|
Property |
420 | 440 (A / B / C) |
|---|---|---|
| Carbon Content | 0.15–0.40% | 440A: ~0.6% → 440C: ~1.2% |
| Hardness Potential | Moderate to High (HRC 50) | Very High (up to HRC 60+) |
| Corrosion Resistance | Moderate | Good to High (440A > C) |
| Wear Resistance | Good | Excellent (especially 440C) |
440C is better than 420 in both hardness and edge retention, but 420 offers easier machinability and better toughness in some cases.
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