420 vs 440C Stainless Steel
Side-by-side comparison · Composition · Properties · Selection guide
420 and 440C are hardenable martensitic stainless steels, but 440C pushes carbon and chromium higher to achieve greater hardness and wear resistance. 420 offers better toughness and manufacturing latitude for blades and instruments, while 440C targets bearings, seats and wear parts that need maximum stainless hardness.
Full datasheets:420 Stainless Steel·440C Stainless Steel
At a Glance
| 420 | 440C | |
|---|---|---|
| Type | Martensitic | Martensitic (high-carbon) |
| UNS | S42000 | S44004 |
| Standard | ASTM A240/A240M, A276 | ASTM A276 |
| Density | 7.75 g/cm³ | 7.75 g/cm³ |
Corrosion Resistance and Service Limits
420
- Corrosion resistance depends on chromium, carbon, heat-treatment condition and surface finish and is generally below common 304-type austenitic stainless steel.
- Avoid assuming hardness implies corrosion resistance. Chlorides, tempering condition, retained scale and grinding contamination must be evaluated for the part.
440C
- Corrosion resistance depends on chromium, carbon, heat-treatment condition and surface finish and is generally below common 304-type austenitic stainless steel.
- Avoid assuming hardness implies corrosion resistance. Chlorides, tempering condition, retained scale and grinding contamination must be evaluated for the part.
Fabrication and Heat Treatment
| Operation | 420 | 440C |
|---|---|---|
| Welding | Welding requires grade- and section-specific preheat, filler and post-weld heat treatment to control hard cracking and restore properties. | Welding requires grade- and section-specific preheat, filler and post-weld heat treatment to control hard cracking and restore properties. |
| Forming | Carry out substantial forming in the annealed condition and allow for reduced ductility as carbon and target hardness increase. | Carry out substantial forming in the annealed condition and allow for reduced ductility as carbon and target hardness increase. |
| Machining | Machine in the annealed or softened condition where possible; hardened material needs appropriate tooling, speeds and allowance for final grinding. | Machine in the annealed or softened condition where possible; hardened material needs appropriate tooling, speeds and allowance for final grinding. |
| Heat treatment | Final properties depend on a specified austenitize, quench and temper route. Temperature, hold time, section size and required hardness belong on the order. | Final properties depend on a specified austenitize, quench and temper route. Temperature, hold time, section size and required hardness belong on the order. |
Chemical Composition (wt%)
| Element | 420 | 440C |
|---|---|---|
| C | ≥0.15 | 0.95–1.20 |
| Mn | ≤1.00 | ≤1.00 |
| Si | ≤1.00 | ≤1.00 |
| Cr | 12.0–14.0 | 16.0–18.0 |
| P | ≤0.040 | ≤0.040 |
| S | ≤0.030 | ≤0.030 |
| Mo | — | ≤0.75 |
Mechanical Properties
| Property | 420 | 440C |
|---|---|---|
| Condition (as supplied) | Annealed | — |
| Hardness (annealed) | ≤223 HBW | ≤269 HBW |
| Hardness (hardened + tempered) | 48–52 HRC (typ.) | — |
| Tensile (hardened, typ.) | ≈1600–1800 MPa | — |
| Hardness (hardened & tempered) | — | 58–60 HRC |
| Tensile strength (hardened, typical) | — | ≈1970 MPa |
| Tensile strength (annealed, typical) | — | ≈760 MPa |
Which One Should You Choose?
Choose 420 for:
- Knives, instruments and general cutting tools
- Parts balancing hardness with toughness
- Components needing easier machining before hardening
- Moderate wear with a finer corrosion-toughness balance
Choose 440C for:
- Bearings, races and high-wear seats
- Precision parts requiring very high hardness
- Wear components with controlled impact loading
- Applications justified by specialist heat treatment
Our verdict
Use 420 when the part needs a practical balance of edge retention, toughness and manufacturability. Choose 440C only when very high hardness and wear life dominate and the component can tolerate lower toughness and tighter heat-treatment control. Both depend on final hardness and surface finish for corrosion behavior.
Cost and Availability
Compare the current stock position, mill route, minimum production quantity, processing yield, testing and delivered cost for 420 and 440C at quotation time. A fixed price ratio would be misleading because product form, size, condition and market timing can change the commercial result.
Do Not Substitute Without Review
Do not replace 420 with 440C, or the reverse, from the grade name alone. Recheck chemistry, mechanical-property condition, product standard, dimensions, corrosion environment, welding procedure and project approval before substitution.
Frequently Asked Questions
Which grade gets harder?
440C. With appropriate heat treatment it can reach the upper-50s HRC or above, while common 420 conditions are normally selected at lower hardness for toughness.
Which is more corrosion resistant?
The answer depends on heat treatment and finish. 440C has more chromium but also more carbon tying chromium into carbides; neither approaches 304 or 316L in wet corrosion service.
Can 420 and 440C be welded?
They are crack-sensitive martensitic grades. Welding is generally avoided for critical parts or performed only with qualified preheat, filler and post-weld heat treatment.
RFQ
Get a 420 or 440C Quotation
Send the specification you have; we will identify missing inputs before quoting.
Technical content updated: 2026-07-29
Organizational author: Tsingshan (Shandong) Iron & Steel Co., Ltd..Review method, status and limitations.