2085 Tool Steel
2085 tool steel is a high-carbon, high-chromium cold-work tool steel known for its excellent wear resistance, high hardness, and good dimensional stability after heat treatment. It is primarily designed for cold working applications where abrasion resistance and edge retention are critical, making it suitable for a range of tooling and die applications.
Basic Information
Definition: 2085 is a cold-work tool steel categorized under the high-chromium family, characterized by a high carbon content and significant chromium addition. It offers a balance of wear resistance, hardenability, and moderate toughness, making it ideal for cold forming, blanking, and machining tools.
Corresponding Standards: While not as universally standardized as some grades, 2085 is often referenced in industrial specifications and is comparable to other high-chromium cold-work steels. It may be equivalent to certain grades in the DIN or GB standards, though exact matches vary by regional specifications.
Key Characteristics: High wear resistance (due to chromium carbides), high hardness after heat treatment, good dimensional stability, and moderate machinability in the annealed state.
Chemical Composition
The composition of 2085 tool steel is tailored to enhance wear resistance and hardenability, with typical ranges as follows:
Element Content Range Role in the Steel
Carbon (C) 1.40–1.60% High carbon content promotes the formation of hard carbides (critical for wear resistance) and enables high hardness after quenching.
Chromium (Cr) 11.00–13.00% The primary alloying element; forms chromium-rich carbides (Cr₇C₃) that significantly enhance wear resistance and improve hardenability.
Manganese (Mn) 0.20–0.60% Aids in deoxidation and improves hardenability slightly.
Silicon (Si) 0.20–0.60% Acts as a deoxidizer and enhances strength during heat treatment.
Molybdenum (Mo) ≤0.60% May be present in small amounts to improve hardenability and reduce temper brittleness.
Vanadium (V) 0.20–0.50% Refines grain structure, enhances toughness, and forms vanadium carbides for additional wear resistance.
Phosphorus (P) ≤0.030% Harmful impurity; strictly controlled to avoid brittleness.
Sulfur (S) ≤0.030% Controlled to prevent reduced toughness and hot cracking during processing.
Physical Properties
Density: Approximately 7.80–7.85 g/cm³ (consistent with most high-chromium tool steels).
Melting Point: Around 1430–1480°C (varies slightly with composition).
Thermal Conductivity: ~30–35 W/(m·K) at room temperature (lower than low-alloy steels due to high carbide content).
Coefficient of Thermal Expansion: ~10.5×10⁻⁶/°C (20–100°C), contributing to good dimensional stability.
Elastic Modulus: ~210 GPa.
Mechanical Properties
2085 tool steel’s performance is optimized through hardening and tempering, with properties focused on wear resistance and hardness:
Annealed State (for Machining)
Hardness: ≤255 HB (soft enough for conventional machining with carbide tools).
Tensile Strength: ~700–800 MPa.
Elongation: ~15–20% (moderate ductility for pre-forming).
After Hardening + Tempering
Tempering Temperature Hardness Tensile Strength Impact Toughness (Charpy V-Notch) Key Property Focus
150–200°C (302–392°F) 60–62 HRC ~2200–2400 MPa ~10–15 J Maximum hardness and wear resistance.
250–300°C (482–572°F) 58–60 HRC ~2000–2200 MPa ~15–20 J Balanced wear resistance and toughness.
350–400°C (662–752°F) 55–57 HRC ~1800–2000 MPa ~20–25 J Improved toughness with slightly reduced wear resistance.
Wear Resistance: Excellent, due to the high volume of hard chromium carbides distributed in the matrix, making it suitable for abrasive environments.
Dimensional Stability: Good—minimal distortion during heat treatment, critical for precision tooling.
Heat Treatment Process
Proper heat treatment is essential to maximize 2085’s wear resistance and hardness while maintaining dimensional stability:
Annealing
Purpose: Soften the steel for machining and prepare the microstructure for hardening.
Process: Heat to 800–850°C, hold for 2–4 hours, then cool slowly (≤20°C/hour) to 600°C, followed by air cooling. Results in a spheroidal carbide structure with hardness ≤255 HB.
Austenitizing (Heating for Hardening)
Temperature: 950–1000°C (1742–1832°F).
Hold Time: 30–60 minutes (depending on part thickness) to dissolve carbides evenly while avoiding grain growth.
Quenching
Cooling Medium: Oil quenching or air cooling (depending on part size); oil quenching ensures full hardening for thicker sections.
Result: Forms martensite, achieving as-quenched hardness of 62–64 HRC.
Tempering
Temperature Range: 150–400°C (302–752°F), with a holding time of 1–2 hours per 25 mm of thickness (double tempering recommended to eliminate retained austenite).
Effect: Reduces internal stress, stabilizes dimensions, and adjusts hardness/toughness balance. Higher temperatures increase toughness but reduce hardness.
Processing Performance
Machinability: Moderate in the annealed state (≤255 HB). Carbides can cause tool wear, so carbide cutting tools or high-speed steel tools with sharp edges are recommended.
Weldability: Poor—high carbon and chromium content make it prone to cracking during welding. Preheating and post-weld heat treatment are required, but welding is generally avoided for critical tools.
Formability: Limited cold formability due to moderate strength in the annealed state. Hot forming is possible at 1050–1150°C, followed by annealing to restore machinability.
Grindability: Good—can be ground to high precision and smooth surfaces, essential for tooling with tight tolerances.
Application Fields
2085 tool steel is primarily used in cold-work applications where wear resistance and edge retention are paramount:
Cold-Work Tooling:
Blanking dies, punching dies, and forming dies for sheet metal processing (resists wear from repeated contact with metal).
Thread rolling dies, wire drawing dies, and extrusion dies for cold forming operations.
Shear blades and slitter knives for cutting hard or abrasive materials (e.g., stainless steel, high-carbon steel).
Industrial Tools:
Wear parts in machinery, such as guides, bushings, and inserts, subjected to abrasive wear.
Precision gauges and measuring tools requiring high hardness and dimensional stability.
Mold Making:
Injection molds for abrasive plastics (e.g., filled with glass fibers) where wear resistance extends mold life.
In summary, 2085 tool steel is a reliable choice for cold-work applications demanding high wear resistance, high hardness, and dimensional stability. Its balance of properties makes it a staple in tooling and die-making industries where durability and precision are critical.