440C Stainless Steel Coil
The 440C stainless steel coil is a high-carbon high-chromium martensitic stainless steel coil. It is renowned for its extremely high hardness and outstanding wear resistance, and is one of the hardest grades among all stainless steels. It is specially designed for applications that have extremely demanding requirements for hardness and wear resistance.
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Product Introduction

440C Stainless Steel Coil represents the pinnacle of high-carbon martensitic stainless steels, engineered to deliver exceptional hardness, superior wear resistance, and excellent edge retention for the most demanding applications. With carbon content of 0.95-1.20%—the highest among standard stainless steels—440C achieves remarkable hardness levels up to 62 HRC after proper heat treatment, making it the premier choice for premium cutlery, high-performance bearings, surgical instruments, and critical wear components. This grade combines extreme hardness capabilities with moderate corrosion resistance, creating a unique material solution where wear resistance and dimensional stability are paramount.

Supplied in continuous coil form for precision manufacturing, 440C offers manufacturers the ability to produce components with exceptional hardness while maintaining the basic corrosion resistance inherent to chromium-containing steels. The high carbon content enables deep hardening and superior abrasion resistance, positioning 440C as the material of choice for applications where other stainless steels lack sufficient hardness and tool steels lack adequate corrosion resistance. While challenging to machine and form, 440C provides unmatched performance in carefully selected applications where its specific properties justify the processing complexity and cost.

Product parameters


Item / ParameterSpecification for 440C Coil (UNS S44004)Notes / Significance
Key FeatureThe Premium Ultra-Hard Martensitic Grade. Exceptionally high carbon content (0.95-1.20%) enables extreme hardness (up to 62 HRC) and superior wear/edge retention for critical applications.The hardest standard stainless steel, used where maximum hardness and wear resistance are required.
Common DesignationsUNS S44004, AISI 440C, EN 1.4125, X105CrMo17, JIS SUS440CPart of 440 series: 440A (lower carbon), 440B, 440C (highest carbon).
Chemical Composition (Typical wt.%)C: 0.95 - 1.20Cr: 16.0 - 18.0
Mo: 0.40 - 0.65Mn: ≤ 1.00
Si: ≤ 1.00
P: ≤ 0.040
S: ≤ 0.030
High carbon enables extreme hardness; molybdenum enhances hardenability and toughness.
Mechanical Properties (Annealed)Tensile Strength (Rm): ≥ 520 - 750 MPa
Yield Strength (Rp0.2): ≥ 345 - 450 MPa
Elongation (A): ≥ 10-15%
Hardness (HB): ≤ 269
Limited ductility even in annealed condition due to high carbon content.
Mechanical Properties (Hardened & Tempered)Tensile Strength: Up to 1900 MPa
Yield Strength: Up to 1650 MPa
Hardness: Up to 62 HRCElongation: 2-5%
Impact Toughness: Low
Achieves the highest hardness of any standard stainless steel.
Physical PropertiesDensity: 7.70 g/cm³
Melting Range: 1370 - 1510 °C
Thermal Conductivity: 24.2 W/m·K
Magnetic: Strongly magnetic
High carbon content affects physical properties; always magnetic.
Heat Treatment CapabilityAustenitizing: 1010-1065°C
Quenching: Oil (critical)
Tempering Range: 150-370°C
Sub-zero Treatment: Recommended
Annealing: 815-870°C, slow cool
Multiple tempering cycles often used; cryogenic treatment improves dimensional stability.
Corrosion ResistanceModerate resistance to water, atmosphere, and mild chemicals. Inferior to 304/316. Requires proper passivation.Better than tool steels but limited compared to lower-carbon stainless grades.
Key Standards (Coil)ASTM A276 (Stainless Steel Bars)
ASTM A480 (General Requirements)
AMS 5630 (Aerospace)
EN 10088-3
ISO 4957
Often supplied as bar rather than coil; coil availability depends on thickness and application.
Common Applications (from Coil)• Premium Cutlery: High-end knives, surgical scalpels, razor blades
• Precision Bearings: Ball bearings, roller bearings, bearing races
• Surgical Instruments: Orthopedic tools, dental instruments, implants
• Industrial Components: Valve seats, pump shafts, measuring tools
• Mold Making: Plastic injection mold cores, high-wear inserts
• Defense/Aerospace: Aircraft bearings, critical wear components
• Food Processing: High-wear cutting blades, slicers
Where extreme hardness and wear resistance justify processing complexity.

Surface selection

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Packaging and transportation

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FACTORY SHOW

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FAQ

Q:What about your price? 
A:Our price is very competitive because we are a factory. Feel free to contact us if you are interested in our products. 

Q:Can I go to your factory to visit?
A:Of course, we welcome customers from all over the world to visit our factory.

Q:What product information do I need to provide?
A:You need to provide the grade, width, thickness, coating and the number of tons you need to purchase. 

Q:Does the product have quality inspection before loading? 
A:Of course, all our products are strictly tested for quality before packaging, and unqualified products will be destroyed.we
accept the third party inspection absolutely. 

Q:How about the delivery time? 
A:Within 3-15 days after we confirm you requirement. 

Q:What is your terms of payment ?
A:T/T, L/C at sight, Cash, Western Union are all accepted if you have other payment,please contact me. 

Q: Do you provide samples? 
A:Yes,we could offer the sample for you to test but please pay freight fee.

Q:How do we trust your company? 
A:We are a specialized company focusing on global steel trading and supply chain services. Our mission is to provide high-quality, multi-specification, and one-stop steel products and solutions to customers worldwide.

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