AISI 440C Stainless Steel Plate | UNS S44004 | 440C Bearing Grade
What is AISI 440C Stainless Steel ?
As a professional China steel mill-Direct Supply and stainless steel plate supplier, SHH STEEL is pleased to present AISI 440C Stainless Steel Plate.
AISI 440C is widely known and searched under many different names and designations, including AISI 440C, UNS S44004, 440C stainless steel, 440C stainless steel plate, 440C bearing steel, SUS440C, 1.4125, X105CrMo17 and high-carbon 16–18% Cr 440C. All these names refer to the highest-carbon member of the 440A / 440B / 440C family.
AISI 440C contains 16.0–18.0% chromium with 0.95–1.20% carbon, plus a small molybdenum addition in many commercial analyses. This chemistry produces the highest hardness and wear resistance of the standard 440 grades after quench and temper. Chromium is much higher than in A240 410 or 420, so corrosion resistance after hardening is better than those lower-chromium martensitics. The grade is magnetic and is normally supplied annealed for later heat treatment.
Typical uses include bearing balls and races, valve seats, nozzles, cutlery, surgical tools, molds and other parts that need maximum stainless wear resistance. 440C is more wear-resistant than 440A or 440B, but also less tough and more difficult to grind. Do not confuse 440C with ferritic A240 430, which has similar chromium but cannot be hardened.
SHH STEEL supplies AISI 440C as true China steel mill-Direct Supply, sourcing directly from major Chinese stainless steel mills. This model delivers competitive mill pricing, consistent quality, complete heat traceability and reliable delivery.
AISI 440C is frequently compared with A240 410, A240 410S, A240 430, A240 429, a240 304 and a240 316l. SHH STEEL provides technical support to help customers choose the most appropriate grade.
Material Specification
| Specification Element | Requirement | SHH STEEL Compliance |
|---|---|---|
| Grade | AISI 440C / UNS S44004 | Confirmed |
| Related Standards | ASTM A276, ASTM A473, JIS SUS440C, EN 1.4125 | Available |
| Product Form | Plate, Sheet, and heat-treatable flat products | Available |
| Delivery Condition | Annealed (hardened + tempered on request) | Standard annealed |
| Thickness Range | 1 mm – 50 mm (thicker available on request) | Custom sizes supported |
| Width | Up to 1500 mm | Available |
| Length | Up to 6000 mm or cut-to-length | Available |
| Surface Finish | No.1, 2B, ground / polished as specified | Available |
| Certification | EN 10204 3.1 / Mill Test Certificate | Available |
SHH STEEL can supply AISI 440C dual-certified to the required designation when specified by the project. Please confirm 440A, 440B or 440C before production.
Chemical Composition
Typical Chemical Composition of AISI 440C (UNS S44004):
| Element | Content (%) |
|---|---|
| Carbon (C) | 0.95 – 1.20 |
| Silicon (Si) | ≤ 1.00 |
| Manganese (Mn) | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.040 |
| Sulfur (S) | ≤ 0.030 |
| Chromium (Cr) | 16.00 – 18.00 |
| Molybdenum (Mo) | ≤ 0.75 |
| Iron (Fe) | Balance |
The defining features of AISI 440C are 16–18% chromium and 0.95–1.20% carbon. This is the highest carbon of the 440 series. Primary carbides give outstanding wear resistance after hardening. SHH STEEL carefully controls carbon and chromium so the grade is not mixed with 440A or 440B.
Mechanical Properties
Annealed Condition (typical values)
| Property | Value |
|---|---|
| Hardness | Soft annealed for machining |
| Formability | Limited |
| Magnetism | Magnetic |
After quench and temper, AISI 440C can reach approximately 58–60 HRC or slightly higher, depending on exact carbon, molybdenum and tempering practice. This is the highest hardness of the standard 440 family. Toughness is lower than 440A or 440B. SHH STEEL normally supplies plate in the annealed condition unless a hardened-and-tempered condition is specified.
Physical Properties
Density is approximately 7.70–7.75 g/cm³. Melting range is approximately 1370–1480°C. The grade is magnetic in all common heat-treated conditions.
Material Comparison
| Grade | UNS | Carbon (%) | Typical Max Hardness | Typical Preference |
|---|---|---|---|---|
| AISI 420 | S42000 | ≥ 0.15 | Medium-high | General cutlery / tools |
| AISI 440A | S44002 | 0.60–0.75 | High | Tougher 440 cutlery |
| AISI 440B | S44003 | 0.75–0.95 | Higher | Intermediate 440 hardness |
| AISI 440C | S44004 | 0.95–1.20 | Highest | Bearings, maximum wear / hardness |
| AISI 410 | S41000 | ≤ 0.15 | Moderate | Valves and general 12% Cr |
| AISI 430 | S43000 | ≤ 0.12 | Not hardenable | Appliances and ferritic plate |
AISI 440C is selected when maximum hardness and wear resistance are required. If toughness or grindability is more important, SHH STEEL recommends 440A or 440B. For welded plate, use A240 410S or A240 430.
Corrosion Resistance
AISI 440C offers better corrosion resistance than 410 and 420 after hardening because of 16–18% chromium. It performs well in mild atmospheres, fresh water and many bearing or cutlery environments when polished and passivated.
It is not equivalent to a240 304 or a240 316l in chloride or acid service. Large primary carbides can slightly reduce pitting resistance compared with lower-carbon 440A in some environments. Maximum corrosion resistance is obtained in the hardened, polished and passivated condition.
Weldability
AISI 440C has very poor weldability because of its very high carbon content. The heat-affected zone becomes extremely hard and crack-sensitive. Welding is generally avoided.
If joining is required, SHH STEEL recommends mechanical fastening or using a lower-carbon grade such as A240 410S for welded sections.
Heat Treatment
AISI 440C is normally supplied in the annealed condition by SHH STEEL and is designed to be hardened by quench and temper.
Typical hardening is performed from about 1010–1065°C, followed by oil or air cooling, often with a sub-zero treatment to reduce retained austenite, then tempering to the required hardness. Over-tempering reduces wear resistance. SHH STEEL can supply annealed plate or discuss hardened-and-tempered supply when the drawing requires it.
Surface Finishes
| Finish | Description | Typical Use / Keywords |
|---|---|---|
| No.1 | Hot-rolled, annealed and pickled | AISI 440C No.1 – industrial plate |
| 2B | Cold-rolled, annealed, pickled, skin-passed | AISI 440C 2B – thinner plate |
| Ground / Polished | Precision ground or polished | AISI 440C polished – bearings, cutlery, tools |
SHH STEEL supplies AISI 440C in the finish required by the bearing, cutlery or wear-part drawing.
Tolerances
Dimensional tolerances for AISI 440C plate supplied by SHH STEEL generally conform to ASTM A480 practices.
Typical available size range is thickness 1 mm – 50 mm, width up to 1500 mm, and length up to 6000 mm or cut-to-length. SHH STEEL provides precise dimensional control and can support tighter tolerances when required.
Equivalent Material Grades
| Grade / Designation | Standard / Region | Notes |
|---|---|---|
| AISI 440C | AISI | Main commercial keyword |
| UNS S44004 | Unified Numbering System | Primary UNS designation |
| 1.4125 / X105CrMo17 | EN (Europe) | European equivalent |
| SUS440C | JIS (Japan) | Japanese equivalent |
| Related 9Cr18Mo / 11Cr17 | GB/T (China) | Chinese related grades |
| Related 440A / 440B | Multiple | Lower-carbon 440 variants |
Related grades for comparison include A240 410, A240 410S, A240 430, A240 429, a240 304 and a240 316l.
Applications
AISI 440C is selected for parts that need the highest hardness and wear resistance in the 440 family. Typical applications of AISI 440C include:
| Industry / Sector | Typical Components / Equipment (with keywords) |
|---|---|
| Bearings | AISI 440C balls, races and bearing components |
| Cutlery | AISI 440C high-wear knife blades |
| Valves & Pumps | AISI 440C seats, nozzles and hardened wear parts |
| Molds & Tools | AISI 440C plastic molds and cutting tools |
| Medical & Dental | AISI 440C instruments requiring maximum hardness |
| Industrial Equipment | UNS S44004 plate for subsequent hardening |
SHH STEEL supplies AISI 440C for these heat-treatable applications with consistent quality. For related industry solutions, see our equipment manufacturing and machinery industry pages. Supporting services include steel cutting services, cnc steel machining services and worldwide shipping service.
Why Choose SHH STEEL
SHH STEEL is a China steel mill-Direct Supply specializing in stainless steel plate and heat-treatable grades. By working directly with major Chinese stainless steel mills, SHH STEEL supplies AISI 440C with the following advantages:
- Genuine China steel mill-Direct Supply pricing
- Consistent quality and complete heat traceability
- Full Mill Test Certificates (EN 10204 3.1)
- High-carbon AISI 440C material optimized for maximum hardness and wear resistance
- Flexible dimensions and finishes (including AISI 440C No.1, AISI 440C 2B and AISI 440C polished)
- Technical support for selection among AISI 420, 440A, 440B and 440C
- Value-added services including steel cutting services, cnc steel machining services and worldwide shipping service
For more information about our company and full product range, please visit China steel Mill Agent-SHH STEEL.
FAQ
- What are the other common names for AISI 440C?AISI 440C is also known as UNS S44004, 440C bearing steel, SUS440C, 1.4125 and X105CrMo17. SHH STEEL can certify the required designation.
- What is the difference between AISI 440C, 440A and 440B?Carbon increases from 440A to 440C. 440C has the highest hardness and wear resistance, but the lowest toughness. SHH STEEL supplies the exact 440 grade named on the purchase order.
- What hardness can AISI 440C reach?Typically about 58–60 HRC after proper quench, optional sub-zero treatment and tempering. SHH STEEL can advise on heat-treatment practice.
- an AISI 440C be hardened?Yes. That is its main purpose. SHH STEEL normally supplies annealed plate unless a hardened condition is specified.
- Is AISI 440C magnetic?Yes. It is magnetic in both the annealed and hardened conditions.
- What is the density of AISI 440C?Approximately 7.70–7.75 g/cm³. SHH STEEL provides mill certificates confirming chemistry and mechanical properties.
- oes SHH STEEL supply dual-certified AISI 440C / UNS S44004 material?Yes, SHH STEEL commonly supplies dual-certified material upon request.
Conclusion
AISI 440C Stainless Steel Plate is the highest-carbon grade in the 440 martensitic family. It is chosen for bearings, valve seats, high-wear cutlery and other parts that need maximum hardness and wear resistance after heat treatment.
As a professional China steel mill-Direct Supply, SHH STEEL provides high-quality AISI 440C / UNS S44004 material with competitive pricing, full certification and complete technical support.
Contact SHH STEEL today for stock availability, confirmation of 440A vs 440B vs 440C, surface finish options (including AISI 440C No.1, AISI 440C 2B and AISI 440C polished), or a competitive quotation.
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