Ultra-High Carbon Steel (UHCS) is a specialised class of carbon steel containing approximately 1.0% to 2.0% carbon, significantly higher than standard high-carbon steels. This exceptionally high carbon content enables UHCS to develop extreme hardness, superior wear resistance, outstanding edge retention, and very high compressive strength after appropriate heat treatment.
UHCS is primarily used in cutting tools, dies, wear-resistant components, blades, springs, and high-stress industrial applications where conventional steels cannot provide sufficient hardness or durability.
Typical Chemical Composition
| Element | Typical Range (%) |
|---|---|
| Carbon (C) | 1.0 – 2.0 |
| Manganese (Mn) | 0.20 – 0.90 |
| Silicon (Si) | ≤ 0.40 |
| Sulphur (S) | ≤ 0.030 |
| Phosphorus (P) | ≤ 0.030 |
| Iron (Fe) | Balance |
Microstructure & Metallurgical Behavior
Ultra-High Carbon Steel contains a very high volume of cementite (Fe₃C) within a pearlitic or martensitic matrix:
• Annealed condition: Fine pearlite + cementite
• Hardened condition: High-carbon martensite + carbides
• Tempered condition: Tempered martensite with controlled carbide dispersion
This carbide-rich microstructure is responsible for exceptional hardness, very high abrasion resistance, and superior edge stability.
Key Characteristics
Very High Hardness & Strength
• Achieves 55–66+ HRC depending on carbon level and heat treatment
• Handles extreme contact stresses and compressive loads
Superior Wear & Abrasion Resistance
• High carbide concentration minimizes surface wear
• Ideal for sliding, cutting, and impact-abrasion environments
Excellent Edge Retention
• Maintains sharp cutting edges over extended cycles
• Highly valued in blades, chisels, and precision tools
Low Ductility & Toughness
• Naturally brittle due to high carbon content
• Tempering is essential for usable toughness
Exceptional Heat-Treatment Response
• Highly sensitive to annealing, quenching, tempering, and cryogenic treatment
Typical Mechanical Properties
| Property | Typical Range |
|---|---|
| Tensile Strength | 1,000 – 1,800 MPa |
| Yield Strength | 600 – 1,200 MPa |
| Hardness | 550 – 800+ HB |
| Rockwell Hardness | 55 – 66+ HRC |
| Elongation | 2 – 8% |
| Impact Toughness | Low (improves after tempering) |
| Density | ~7.85 g/cm³ |
| Modulus of Elasticity | ~200 GPa |
Heat Treatment Characteristics
• Controlled preheating to prevent thermal shock
• Quenching in oil, polymer, or salt bath
• Carefully selected tempering temperatures
• Optional cryogenic treatment for carbide stability
Machinability & Weldability
Machinability:
• Poor in hardened condition
• Fair only when fully annealed
• Requires carbide or ceramic tooling
Weldability:
• Very poor and generally avoided
• Requires extensive preheat and post-weld heat treatment if unavoidable
Available Forms
✔ Bars (round, square, flat)
✔ Sheets & plates
✔ Forged blocks & billets
✔ Wires & rods
✔ Precision strips & coils
✔ Custom-machined components
Applications
Industrial: Cutting tools, dies, punches, wear plates, springs
Construction & Mining: Drilling tools, masonry cutters, agricultural implements
Specialty: Knives, swords, razor tools, precision instruments
Advantages
✔ Extreme hardness and abrasion resistance
✔ Outstanding cutting performance
✔ High compressive strength
✔ Long service life in wear-intensive applications
✔ Cost-effective alternative to some alloy tool steels
Limitations
⚠ Very low ductility
⚠ Poor weldability
⚠ Requires precise heat-treatment control
⚠ Susceptible to cracking if mishandled
⚠ Requires corrosion protection
Why Choose Ultra-High Carbon Steel
Ultra-High Carbon Steel is selected when maximum hardness, extreme wear resistance, and long-lasting cutting performance are non-negotiable. While it demands careful processing, its unmatched durability and edge stability make it indispensable in tooling, heavy industry, mining, construction equipment, precision engineering, and specialty blade applications.