440A Stainless Steel
440A is a high-carbon martensitic stainless steel designed for higher hardness than 420 grades, with a strong balance of stain resistance, edge holding, and cost control. It is widely used for knives, cutting parts, and wear components where heat treatment is part of the manufacturing process.
440A is magnetic and heat treatable. Final performance depends on heat treatment settings, section size, and surface finishing. For appearance or stain control, surface condition matters as much as chemistry.
Grade type
Martensitic, high carbon
Made for hardness and wear control.
Typical hardness (heat treated)
About 56–59 HRC
Common range for blades and cutters.
Corrosion behavior
Good stain resistance
Best with clean, polished surfaces.
Best-fit parts
Knives and wear parts
Edge holding with stable supply.
440A is used when hardness and edge retention are important, but the service environment still needs practical stain resistance. It is common in consumer and industrial cutting parts.
- Knife blades: outdoor, utility, and selected kitchen knife products
- Cutting parts: cutters, trimming tools, and edge components
- Wear components: guides, bushings, and small wear parts in mild corrosion exposure
- Precision parts: pins, shafts, and small mechanical components
- Food-contact tooling: selected tools where cleaning and hardness both matter
440A may appear under different naming systems. Equivalents help cross-reference, but your RFQ should still define the target standard, product form, condition, and inspection requirements.
| System | Designation | Note |
|---|---|---|
| ASTM / AISI | 440A | Common name in blade supply chains |
| UNS | S44002 | Used on Mill Test Certificates |
| JIS | SUS440A | Common ordering name in Asia |
| EN | 1.4109 | European grade number (often referenced) |
| DIN | X70CrMo15 (reference) | Confirm chemistry on the MTC |
| GB (reference) | 7Cr17 (reference) | Cross-check by chemistry and condition |
- Edge holding: higher carbon supports stronger edge retention than 420 grades.
- Wear resistance: suitable for cutting and sliding contact parts in mild service.
- Stain resistance: good resistance in everyday use when the surface is clean and finished.
- Heat treatable: performance depends on quench and temper control.
- Magnetic: magnetic in both annealed and hardened conditions.
Limits vary slightly by specification. The Mill Test Certificate is the final verification for your delivered heat.
| Basis | C | Cr | Mo | Mn | Si | P | S | Fe |
|---|---|---|---|---|---|---|---|---|
| Typical 440A / S44002 reference | 0.60–0.75 | 16.0–18.0 | ≤ 0.75 | ≤ 1.0 | ≤ 1.0 | ≤ 0.04 | ≤ 0.03 | Balance |
Properties depend on section size and condition. Use the governing specification for acceptance.
| Condition | Hardness | Typical use | Notes |
|---|---|---|---|
| Annealed (reference) | ≤ 255 HB | Machining and forming before heat treatment | Common condition for bar and plate supply |
| Quenched & tempered (typical) | 56–59 HRC | Knives, cutters, wear parts | Final values depend on tempering and section size |
440A offers good stain resistance for daily-use environments, especially when the surface is polished and kept clean. It performs well in humidity, indoor air, and typical food-contact handling with proper cleaning practice.
It is not recommended for long exposure to saltwater or strong chlorides. If the part will run in coastal spray, clean and dry handling routines can help reduce surface staining.
440A can be supplied in common stainless product forms. Availability depends on finish, tolerance, straightness, and inspection scope. Share your sizes and end use to align the best supply route.
| Form | Typical size range | Notes |
|---|---|---|
| Sheet (cold rolled) | 0.3–6.0 mm, width 1000–2000 mm | Used for cut-to-length and finishing |
| Plate (hot rolled) | 3–100 mm, width 1000–2000 mm | Common machining stock for wear parts |
| Coil (cold rolled) | 0.3–6.0 mm, width 1000–2000 mm | Slitting and cut-to-length available |
| Strip | 0.3–6.0 mm, width 7–600 mm | Often used for stamped cutting components |
| Round bar | Dia. 1–200 mm, length 100–12000 mm | Common for blades, tools, and turned parts |
| Flat bar / shapes | Flat 20–800 mm, thickness 3–60 mm | Define straightness and tolerance if needed |
- Machining: best in annealed condition. Use rigid setup and cutting fluid to control heat.
- Grinding: common for blades; manage heat to avoid surface burn or distortion.
- Forming: suitable for simple forming. It is not designed for deep drawing.
- Welding: possible with controlled procedures, but cracking risk must be managed.
- Finishing: polishing helps improve stain resistance in daily use.
The ranges below are general reference values. The right cycle depends on section size, hardness target, and distortion control requirements.
| Step | Typical range | Purpose |
|---|---|---|
| Anneal | 760–800°C, slow cool | Softens for machining and shaping |
| Harden | 1010–1065°C, oil or air quench | Builds hardness and wear resistance |
| Temper | 150–400°C | Balances hardness with toughness |
These grades are often compared for blades and wear parts. 440A is a balanced option: strong hardness potential and good stain resistance, with easier processing than the highest-carbon options.
| Topic | 420HC | 440A | 440C |
|---|---|---|---|
| Carbon level | Medium | High | Very high |
| Hardness potential | Medium–high | High | Very high |
| Stain resistance | Good | Good–very good | Very good |
| Typical positioning | Cost and toughness balance | Edge holding + stain control | Maximum edge and wear |
Use these internal tools to confirm equivalents, check hardness, and prepare a clear RFQ before purchasing.
Is 440A stainless steel magnetic?
Yes. 440A is a martensitic stainless steel, so it is magnetic in annealed and hardened conditions.
What is 440A mainly used for?
It is widely used for knives, cutting parts, and wear components where hardness and stain resistance are both needed.
Does 440A rust?
It offers good stain resistance in daily use, especially with a clean, polished surface. It is not designed for long saltwater exposure.
What information helps you quote faster?
Grade and standard, product form, size range, surface finish, tolerance, quantity, required tests, packing request, and destination port.
