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440C Martensitic Stainless
Complete Technical Data Sheet for 440C Martensitic Stainless Chemical Composition Mechanical Properties Physical Properties International Standards & Grade Equivalents Key Applications of 440C Martensitic Stainless Bearings Precision ball and roller bearings made from 440C withstand continuous friction, high-load environments, and offer outstanding durability in both industrial and aerospace settings. Cutlery and Knives 440C blades deliver […]
Description
440C Martensitic Stainless Steel Available in All Types
Stainless Steel Plates
Our 440C plates are the ideal starting stock for fabricating high-wear components that demand exceptional hardness and a good level of corrosion resistance. After heat treatment, this material provides a durable, flat surface perfect for manufacturing cutting tools, mold inserts, and heavy-duty industrial blades that can withstand intense abrasion.
Stainless Steel Bars/Rods
Available in round, square, and flat profiles, our 440C bars and rods are a superior choice for machining high-strength, wear-resistant parts. This material is prized for its ability to be heat-treated to a very high hardness, making it perfect for creating ball bearings, valve components, shafts, and other precision parts that require extreme durability.
Stainless Steel Tubes/Pipes
Engineered for specialized applications requiring a hard, wear-resistant bore, our 440C seamless tubes and pipes offer unparalleled performance. After hardening, the internal surface provides excellent resistance to abrasion and corrosion, making this tubing a top-tier choice for manufacturing bushings, bearing races, and sleeves in high-wear environments.
Stainless Steel Coils
Supplied in the annealed condition for optimal formability, our 440C coils are designed for producing high-volume, hardened components. This thin-gauge material is perfect for stamping and forming parts like knife blades, surgical instruments, and wear plates that will be subsequently heat-treated to achieve maximum hardness and edge retention.
Stainless Steel Wire
Our 440C wire is drawn to precise tolerances for manufacturing components that demand the highest levels of hardness and strength. In its heat-treated state, this wire offers superior wear resistance, making it an excellent material for creating precision bearings, small cutting instruments, and specialized springs where durability is the primary requirement.
Stainless Steel Forgings
For critical components requiring maximum strength and fatigue resistance, our 440C forgings deliver unmatched structural integrity. The forging process refines the grain structure, enhancing the steel’s inherent toughness and strength after hardening, making it the premier choice for creating durable valve bodies, gears, and custom hand tools.
Complete Technical Data Sheet for 440C Martensitic Stainless
| Element | 440C / S44004 (wt%) |
|---|---|
| Carbon (C) | 0.95 – 1.20 |
| Chromium (Cr) | 16.0 – 18.0 |
| Molybdenum (Mo) | ≤ 0.75 |
| Manganese (Mn) | ≤ 1.00 |
| Silicon (Si) | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.040 |
| Sulfur (S) | ≤ 0.030 |
| Property | Typical Values (Hardened to ~58 HRC) |
|---|---|
| Tensile Strength | 2030 MPa (295 ksi) |
| Yield Strength (0.2% Offset) | 1900 MPa (275 ksi) |
| Elongation | 2% |
| Hardness (Rockwell C) | 58 – 60 HRC |
| Impact Strength (Charpy V-Notch) | Low (not recommended for high-impact use) |
| Property | Typical Value at 20°C (68°F) |
|---|---|
| Density | 7.7 g/cm³ (0.278 lb/in³) |
| Modulus of Elasticity | 200 GPa (29,000 ksi) |
| Thermal Conductivity | 200 GPa (29,000 ksi) |
| Coefficient of Thermal Expansion | 10.2 µm/m·°C (from 0-100°C) |
| Electrical Resistivity | 0.60 µΩ·m |
| Standard | Equivalent Grade Designation |
|---|---|
| UNS | S44004 |
| EN (European Standard) | 1.4125 |
| JIS (Japanese Standard) | SUS 440C |
| ASTM | A276, A314, A473, A484, A493, A580, A756 |
| AMS | 5618, 5630, 5880 |
Mechanical Properties of 440C Stainless Steel
Hardness and Strength
The hardness and strength of 440C stainless steel are among its most defining features. When heat treated, this material achieves a high hardness level, making it ideal for applications where wear resistance is paramount. The hardness and wear resistance properties allow it to withstand intense use, maintaining its structural integrity over time. The highest strength attainable in 440C makes it a preferred choice for high-stress environments.
Tensile and Yield Strength
440C stainless steel offers impressive tensile and yield strength, making it suitable for heavy-duty applications. The steel’s high strength is achieved through a precise heat treatment process, which involves quenching in warm oil and tempering. This treatment enhances the steel’s ability to withstand high tension and stress without deformation. Its mechanical properties make it an excellent choice for components that require reliable performance under load.
Impact Toughness
While 440C stainless steel is known for its hardness, its impact toughness also plays a crucial role in its performance. Although not as ductile as some other stainless alloys, 440C maintains a balance between hardness and toughness, allowing it to absorb impact to a certain extent without fracturing. This characteristic is particularly valuable in applications where both high hardness and some level of impact resistance are required.
440C vs 304 Stainless Steel
When comparing 440C to 304 stainless steel, it is essential to note their distinct differences. While 304 is known for its excellent corrosion resistance and ductility, 440C stands out for its higher hardness and wear resistance. The high carbon content in 440C allows it to reach higher strength levels than 304, making it suitable for applications requiring maximum durability. However, it is important to consider the reduction in mechanical properties by over-tempering, which can affect the overall performance of 440C.
Key Applications of 440C Martensitic Stainless
Bearings
Precision ball and roller bearings made from 440C withstand continuous friction, high-load environments, and offer outstanding durability in both industrial and aerospace settings.
Cutlery and Knives
440C blades deliver exceptional sharpness and maintain their cutting edge even during heavy and repetitive use, making them the top choice for premium kitchen and outdoor knives.
Surgical Instruments
Medical and dental tools crafted from 440C benefit from easily sterilized surfaces, enduring sharp points and edges, and consistent reliability in demanding healthcare settings.
What Our Clients Say
“440C stainless steel exceeded our expectations for performance and consistency. Our bearings have lasted significantly longer since the switch. The machining process was straightforward, and the product quality is top-notch.”
Jordan Lewis
Lead Engineer
“Switching to 440C for our surgical instruments has resulted in sharper edges, better wear resistance, and a noticeable reduction in maintenance needs. Our surgeons appreciate the enduring sharpness and reliability.”
Ashley Chen
Procurement Manager
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Frequently Asked Questions
What is 440C Martensitic Stainless Steel?
440C is a high-carbon martensitic stainless steel known for its exceptional hardness, wear resistance, and moderate corrosion resistance, especially after heat treatment.
How hard can 440C stainless steel get after heat treatment?
When properly heat treated, 440C can reach a maximum hardness of approximately 58–60 HRC, making it one of the hardest stainless steels available.
What are the main applications of 440C stainless steel?
440C is widely used for bearings, cutting tools, surgical instruments, valve components, molds, and other high-wear applications requiring superior strength and edge retention.
How does 440C compare to 304 stainless steel?
440C offers significantly higher hardness and wear resistance than 304, which is more commonly chosen for its formability and superior corrosion resistance in less demanding environments.
Is 440C considered a type of hardened stainless steel?
Yes, 440C is classified as a hardened stainless steel because it achieves maximum strength and hardness after proper heat treatment.
What are the corrosion resistance properties of 440C?
440C provides moderate corrosion resistance suitable for mild and non-chloride environments. For harsh or marine conditions, other grades may be more appropriate.
What surface finishes are available for 440C components?
440C can be finished with a variety of techniques, including ground, polished, and mirror finishes, to meet aesthetic and functional requirements.
Is 440C suitable for cryogenic applications?
440C maintains its strength and hardness at low temperatures, but due to its moderate corrosion resistance, care must be taken if used in cryogenic or chloride-rich environments.
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