AISI 440B Stainless Steel Plate | UNS S44003 | 440B Cutlery Grade
What is AISI 440B Stainless Steel?
As a professional China steel mill-Direct Supply and stainless steel plate supplier, SHH STEEL is pleased to present AISI 440B Stainless Steel Plate.
AISI 440B is widely known and searched under many different names and designations, including AISI 440B, UNS S44003, 440B stainless steel, 440B stainless steel plate, 440B cutlery steel, SUS440B and high-carbon 16–18% Cr 440B. All these names refer to the intermediate-carbon member of the 440A / 440B / 440C family.
AISI 440B contains 16.0–18.0% chromium with 0.75–0.95% carbon. Carbon is higher than 440A and lower than 440C, so hardness after heat treatment sits between the two. Chromium is much higher than in A240 410 or 420, giving better corrosion resistance after hardening. The grade is magnetic and is normally supplied annealed for later heat treatment.
Typical uses include cutlery, surgical tools, wear parts, valve components and other parts that need higher hardness than 440A without the maximum brittleness of 440C. Do not confuse 440B with ferritic A240 430, which has similar chromium but cannot be hardened.
SHH STEEL supplies AISI 440B 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 440B 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 440B / UNS S44003 | Confirmed |
| Related Standards | ASTM A276 related, JIS SUS440B | 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 440B 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 440B (UNS S44003):
| Element | Content (%) |
|---|---|
| Carbon (C) | 0.75 – 0.95 |
| 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 440B are 16–18% chromium and 0.75–0.95% carbon. This places the grade between 440A (0.60–0.75% C) and 440C (0.95–1.20% C). SHH STEEL carefully controls carbon so the grade is not mixed with 440A or 440C.
Annealed Condition (typical values)
| Property | Value |
|---|---|
| Hardness | Soft annealed for machining |
| Formability | Limited |
| Magnetism | Magnetic |
After quench and temper, AISI 440B can reach approximately 56–59 HRC, depending on exact carbon and tempering temperature. Hardness is higher than 440A and slightly lower than 440C. 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 hardness / wear |
| 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 440B is selected when the drawing specifies an intermediate 440 hardness. If maximum toughness is needed, choose 440A. If maximum wear resistance is needed, choose 440C. For welded plate, SHH STEEL recommends A240 410S or A240 430.
Corrosion Resistance
AISI 440B 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 food-contact cutlery environments when polished and passivated.
It is not equivalent to a240 304 or a240 316l in chloride or acid service. Maximum corrosion resistance is obtained in the hardened, polished and passivated condition.
Weldability
AISI 440B has poor weldability because of high carbon. The heat-affected zone becomes very 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.
AISI 440B Heat Treatment
AISI 440B 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 and tempering to the required hardness. Sub-zero treatment is sometimes used to reduce retained austenite. SHH STEEL can supply annealed plate or discuss hardened-and-tempered supply when the drawing requires it.
AISI 440B Surface Finishes
| Finish | Description | Typical Use / Keywords |
|---|---|---|
| No.1 | Hot-rolled, annealed and pickled | AISI 440B No.1 – industrial plate |
| 2B | Cold-rolled, annealed, pickled, skin-passed | AISI 440B 2B – thinner plate |
| Ground / Polished | Precision ground or polished | AISI 440B polished – cutlery and tool blanks |
SHH STEEL supplies AISI 440B in the finish required by the cutlery or wear-part drawing.
AISI 440B Tolerances
Dimensional tolerances for AISI 440B 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 440B | AISI | Main commercial keyword |
| UNS S44003 | Unified Numbering System | Primary UNS designation |
| SUS440B | JIS (Japan) | Japanese equivalent |
| Related high-C 17% Cr | EN / GB | Closest national grades |
| Related 440A / 440C | Multiple | Lower / higher carbon 440 |
Related grades for comparison include A240 410, A240 410S, A240 430, A240 429, a240 304 and a240 316l.
Applications
AISI 440B is selected for hardened cutlery and wear parts that need an intermediate 440 hardness. Typical applications of AISI 440B include:
| Industry / Sector | Typical Components / Equipment (with keywords) |
|---|---|
| Cutlery | AISI 440B knife blades and kitchen tools |
| Medical & Dental | AISI 440B instruments requiring high hardness |
| Wear Parts | AISI 440B guides, blades and wear plates |
| Valves & Pumps | AISI 440B seats and hardened small components |
| General Engineering | AISI 440B tool blanks and machined wear parts |
| Industrial Equipment | UNS S44003 plate for subsequent hardening |
SHH STEEL supplies AISI 440B 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 440B 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)
- Carbon-controlled AISI 440B material positioned between 440A and 440C
- Flexible dimensions and finishes (including AISI 440B No.1, AISI 440B 2B and AISI 440B 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 440B?AISI 440B is also known as UNS S44003, 440B cutlery steel and SUS440B. SHH STEEL can certify the required designation.
- What is the difference between AISI 440B, 440A and 440C?Carbon increases from 440A to 440C. 440B is the middle grade: harder than 440A, tougher than 440C. SHH STEEL supplies the exact 440 grade named on the purchase order.
- hat is the difference between AISI 440B and AISI 420?440B has much higher chromium and higher carbon, so it hardens more and resists corrosion better after heat treatment. SHH STEEL recommends 440B when 420 hardness is not enough.
- Can AISI 440B be hardened?Yes. That is its main purpose. SHH STEEL normally supplies annealed plate unless a hardened condition is specified.
- Is AISI 440B magnetic?Yes. It is magnetic in both the annealed and hardened conditions.
- hat is the density of AISI 440B?Approximately 7.70–7.75 g/cm³. SHH STEEL provides mill certificates confirming chemistry and mechanical properties.
- oes SHH STEEL supply dual-certified AISI 440B / UNS S44003 material?es, SHH STEEL commonly supplies dual-certified material upon request.
Conclusion
AISI 440B Stainless Steel Plate is the intermediate-carbon grade in the 440 high-carbon martensitic family. It is chosen for cutlery and wear parts that need higher hardness than 440A without moving fully to 440C.
As a professional China steel mill-Direct Supply, SHH STEEL provides high-quality AISI 440B / UNS S44003 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 440B No.1, AISI 440B 2B and AISI 440B polished), or a competitive quotation.
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