JIS SKS2 Oil-Hardening Cold Work Tool Steel

JIS SKS2 Oil-Hardening Cold Work Tool Steel Product Information -:- For detailed product information, please contact sales. -: JIS SKS2 Oil-Hardening Cold Work Tool Steel Synonyms -:- For detailed product information, please contact sales. -:

JIS SKS2 Oil-Hardening Cold Work Tool Steel Product Information -:- For detailed product information, please contact sales. -: # **JIS SKS2 Oil-Hardening Cold Work Tool Steel** **International Standard:** JIS G4404 (Japan Industrial Standard) - Tool Steels --- ## **1. Overview** JIS SKS2 is a **medium-carbon, low-alloy oil-hardening cold work tool steel** belonging to the SKS (Silicon-Chromium) series. Characterized by its **good machinability, minimal distortion during heat treatment, and excellent wear resistance after hardening**, SKS2 is a versatile and economical choice for a wide range of cold work tooling applications. It offers a balanced combination of hardness, toughness, and dimensional stability, making it particularly suitable for intricate tools and parts requiring precise heat treatment with minimal size change. --- ## **2. Chemical Composition (Typical Weight %)** | Element | Content (%) | | :------ | :---------- | | C | 0.95–1.10 | | Si | 0.15–0.35 | | Mn | 0.90–1.20 | | Cr | 0.50–1.00 | | W | 0.50–1.00 | | V | 0.10–0.25 | | P (max) | 0.030 | | S (max) | 0.030 | **Balance:** Iron (Fe). **Key Characteristics:** SKS2 features a **moderate alloy content with tungsten and chromium** for hardenability and wear resistance, while maintaining a composition that ensures good machinability in the annealed state and relatively low distortion during oil quenching. The combination of around 1% carbon with these alloying elements allows it to achieve good hardness while retaining reasonable toughness. --- ## **3. Physical & Mechanical Properties** ### **Physical Properties** - **Density:** ~7.83 g/cm³ - **Thermal Conductivity:** ~45 W/m·K (at 20°C) – Relatively good for a tool steel - **Coefficient of Thermal Expansion:** ~12.5 ×10⁻⁶ /K (20–200°C) - **Specific Heat Capacity:** ~0.46 kJ/kg·K - **Modulus of Elasticity:** ~210 GPa ### **Mechanical Properties (Heat-Treated)** - **Annealed Hardness:** 187–229 HB - **Hardened & Tempered Hardness:** **57–62 HRC** (typical working range) - **Tensile Strength:** ~2000–2200 MPa (at 60 HRC) - **Yield Strength:** ~1800–2000 MPa - **Elongation:** ~5–10% (depending on hardness) - **Impact Toughness:** **Good** – Better than many high-alloy cold work steels at similar hardness - **Wear Resistance:** **Good** – Suitable for many cold work applications - **Compressive Strength:** ~2500–2800 MPa --- ## **4. Heat Treatment Specifications** ### **1. Annealing** - **Temperature:** 750–800°C - **Process:** Heat uniformly, hold for 2–4 hours, furnace cool slowly (≤ 20°C/h) to 550°C, then air cool - **Resulting Hardness:** 187–229 HB (optimal for machining) - **Spheroidize Annealing:** Recommended for best machinability: 760–780°C, hold 4–6 hours, cool slowly (10°C/h) to 600°C ### **2. Stress Relieving** - **Temperature:** 600–650°C - **Hold Time:** 1–2 hours per 25mm thickness - **Cooling:** Air cool - **Purpose:** Reduce machining stresses, minimize distortion during final hardening ### **3. Hardening (Quenching)** - **Preheating:** Recommended for complex parts - **First Preheat:** 400–500°C (optional but beneficial) - **Second Preheat:** 700–750°C (recommended for uniform heating) - **Austenitizing Temperature:** **780–850°C** (typically 800–830°C) - **Soaking Time:** 20–30 minutes per 25mm at temperature - **Quenching Medium:** **Oil** (warm oil at 40–80°C recommended for minimal distortion) - **Quenching Temperature:** Quench from austenitizing temperature to 50–70°C ### **4. Tempering** - **Immediate Tempering Required:** Begin when tool reaches 50–80°C - **Temperature Range:** **150–250°C** for maximum hardness (58–62 HRC) - Can be tempered at higher temperatures (up to 500°C) for increased toughness with reduced hardness - **Hold Time:** 1–2 hours per 25mm thickness, minimum 1 hour - **Cycles:** Single temper usually sufficient; double tempering improves dimensional stability for precision tools ### **5. Sub-Zero Treatment** - **Generally Not Required:** Due to low retained austenite content - **Optional:** For maximum dimensional stability in precision tools, treat at -70 to -100°C before tempering --- ## **5. Key Features & Advantages** 1. **Minimal Distortion:** Oil quenching results in less distortion and size change compared to water-hardening steels, ideal for intricate tools 2. **Good Machinability:** In annealed condition, offers excellent machinability compared to higher-alloy tool steels 3. **Economical:** Lower alloy content makes it more cost-effective than many other tool steels 4. **Good Toughness-Hardness Balance:** Achieves good hardness while maintaining reasonable impact resistance 5. **Versatile Heat Treatment:** Can be heat treated with relatively simple equipment 6. **Good Wear Resistance:** Adequate for many cold work applications 7. **Relatively Deep Hardening:** Sufficient hardenability for medium-sized sections **Limitations:** - **Limited Hot Hardness:** Not suitable for applications involving significant heat generation - **Moderate Wear Resistance:** Less wear resistant than higher-alloy steels like D2 or high-speed steels - **Section Size Limitations:** Hardenability limited compared to air-hardening grades --- ## **6. Typical Applications** SKS2 is widely used for various **cold work tooling applications** where good wear resistance, reasonable toughness, and economical cost are important. ### **Cutting & Shearing Tools:** - **Hand Tools:** Chisels, punches, screwdrivers, cold chisels - **Cutting Blades:** Leather cutting knives, paper cutting blades, fabric cutters - **Shear Blades:** For cutting soft metals, plastics, and other materials - **Woodworking Tools:** Planer blades, carving tools ### **Forming Tools:** - **Punches and Dies:** For blanking, piercing, and forming of mild steel, brass, aluminum - **Bending Tools:** Press brake dies and punches - **Drawing Dies:** For shallow drawing operations - **Thread Rolling Dies:** For softer materials - **Knurling Tools:** For producing patterns on cylindrical surfaces ### **Measuring & Precision Tools:** - **Gauges:** Plug gauges, ring gauges, thread gauges - **Template:** For inspection and layout - **Machine Parts:** Bushings, wear plates, guide pins ### **Miscellaneous Tooling:** - **Lathe Centers:** For supporting workpieces - **Marking Tools:** Scribers, center punches - **Slitting Saws:** For cutting non-ferrous metals and plastics - **Embossing Dies:** For decorative work --- ## **7. International Standard Equivalents** | Standard | Grade Designation | Notes | | :--------------- | :------------------ | :----------------------------------------- | | **JIS** | SKS2 | Original specification (JIS G4404) | | **AISI/SAE (USA)**| O1 | **Direct Equivalent** (Oil-hardening 1) | | **DIN (Germany)** | 1.2510 | Close equivalent | | **ISO** | 95MnWCr1 | International designation | | **BS (UK)** | BO1 | British standard | | **GB (China)** | 9CrWMn | Similar composition | | **UNS** | T31501 | Unified Numbering System | --- ## **8. Machining & Fabrication Guidelines** ### **Machining (In Annealed State):** - **Excellent Machinability:** One of the most machinable tool steels - **Tooling:** High-speed steel tools work well; carbide for production - **Cutting Speeds:** Can use higher speeds than most tool steels - **Feeds:** Moderate to heavy feeds possible - **Chip Control:** Produces discontinuous chips; use chipbreakers ### **Grinding:** - **Good Grindability:** Responds well to grinding operations - **Wheel Selection:** Aluminum oxide wheels (A46-JV or similar) - **Coolant:** Use coolant to prevent overheating and maintain hardness - **Parameters:** Standard grinding parameters suitable ### **Electrical Discharge Machining (EDM):** - **Suitable:** Can be EDMed in hardened or annealed state - **Post-EDM:** Temper at 150–180°C to relieve stresses from white layer ### **Welding:** - **Possible with Care:** Can be welded using appropriate techniques - **Preheat:** 200–300°C recommended - **Filler Material:** Use matching or slightly lower carbon filler - **Post-Weld:** Anneal or re-harden entire tool for best results --- ## **9. Surface Treatment** ### **1. Nitriding:** - **Effective Treatment:** Improves surface hardness and wear resistance - **Process:** Gas or liquid nitriding at 500–550°C - **Case Depth:** 0.1–0.3 mm typical - **Surface Hardness:** 700–900 HV - **Caution:** May reduce core hardness if temperature exceeds tempering temperature ### **2. Carburizing:** - **Occasionally Used:** For special applications requiring very high surface carbon - **Process:** Pack or gas carburizing - **Result:** Creates high-carbon case on medium-carbon core ### **3. Phosphate Coating:** - **Common for Some Tools:** Improves corrosion resistance and lubricity - **Application:** Often used on punches and dies ### **4. Chrome Plating:** - **For Corrosion Resistance:** Thin decorative or hard chrome - **For Wear Resistance:** Hard chrome plating (0.01–0.05 mm) --- ## **10. Performance Comparison** ### **Within Oil-Hardening Tool Steel Family:** | Property | SKS2 (O1) | SKS3 (O2) | SKS21 (L6) | SKS4 (W1) | |-----------------------|--------------|--------------|--------------|--------------| | **Carbon Content** | 0.95–1.10% | 0.85–0.95% | 0.70–0.80% | 1.00–1.10% | | **Alloy Content** | Medium | Low | Medium | Very Low | | **Distortion** | Low | Very Low | Low | High | | **Machinability** | Excellent | Excellent | Good | Excellent | | **Hardenability** | Good | Fair | Good | Poor | | **Wear Resistance** | Good | Fair | Good | Fair | | **Toughness** | Good | Very Good | Excellent | Fair | ### **Compared to Other Cold Work Steels:** | Property | SKS2 (O1) | SKD11 (D2) | SKD1 (A2) | SKS8 (A6) | |-----------------------|--------------|--------------|--------------|--------------| | **Hardening Method** | Oil | Air | Air | Air | | **Max Hardness** | 62 HRC | 62 HRC | 62 HRC | 62 HRC | | **Distortion** | Low | Very Low | Very Low | Very Low | | **Wear Resistance** | Good | Excellent | Very Good | Good | | **Toughness** | Good | Fair | Very Good | Excellent | | **Machinability** | Excellent | Fair | Good | Good | | **Cost** | Low | High | Medium | Medium | --- ## **11. Design & Manufacturing Considerations** ### **Section Size Limitations:** - **Fully Hardenable:** Up to approximately 25 mm diameter/ thickness - **Surface Hardening Only:** Up to 75 mm (with reduced core hardness) - **Large Sections:** Consider air-hardening grades for sections > 75 mm ### **Stress Relief:** - **Essential After Rough Machining:** Minimizes distortion during final hardening - **Temperature:** 600–650°C - **Before Hardening:** Always stress relieve complex or heavily machined tools ### **Dimensional Changes:** - **During Heat Treatment:** Typically 0.05–0.15% growth - **During Tempering:** Minimal change - **Design Allowance:** Include appropriate machining allowance for finishing after hardening ### **Tool Geometry:** - **Avoid Sharp Corners:** Radius all corners (minimum 0.5 mm) to prevent cracking - **Uniform Sections:** Design for uniform wall thickness where possible - **Gradual Transitions:** Use generous fillets and tapers --- ## **12. Quality Control** ### **Hardness Testing:** - **Rockwell C Scale:** For hardened material - **Brinell or Rockwell B:** For annealed material - **Multiple Readings:** Take at various locations for uniformity ### **Microstructure Examination:** - **Annealed Condition:** Spheroidized carbides in ferritic matrix - **Hardened Condition:** Fine tempered martensite with dispersed carbides - **Grain Size:** ASTM 8 or finer desired ### **Non-Destructive Testing:** - **Magnetic Particle:** For surface cracks after heat treatment - **Dye Penetrant:** Alternative for non-magnetic applications - **Dimensional Verification:** Critical for precision tools --- ## **13. Summary & Selection Guidelines** JIS SKS2 (AISI O1) is a **versatile, economical oil-hardening cold work tool steel** that offers an excellent balance of properties for a wide range of tooling applications. ### **Select SKS2 When:** 1. **Good machinability** is important for tool manufacturing 2. **Minimal distortion** during heat treatment is required 3. **Tool complexity** necessitates oil quenching for dimensional control 4. **Cost-effectiveness** is a significant consideration 5. **Wear resistance requirements** are moderate 6. **Tool size** is within its hardenability limits 7. **Toughness** needs to be balanced with hardness ### **Optimal Application Examples:** - **Intricate punches and dies** requiring precise dimensions - **Hand tools** needing good edge retention - **Prototype tooling** where machinability speeds development - **Low-to-medium production** tooling - **Tools subject to moderate impact** as well as wear ### **Consider Alternatives When:** - **Extreme wear resistance** is needed (consider D2 or high-speed steels) - **Very high toughness** is primary requirement (consider SKS21/L6) - **Large section sizes** exceed hardenability limits (consider air-hardening grades) - **High temperature** operation is involved (consider hot work steels) - **Maximum dimensional stability** is critical (consider air-hardening grades) ### **Economic Advantages:** - **Lower material cost** than most alloy tool steels - **Reduced machining costs** due to excellent machinability - **Lower heat treatment costs** compared to some air-hardening grades - **Good tool life** for many applications ### **Heat Treatment Simplicity:** SKS2's oil-hardening characteristics make it suitable for shops with basic heat treatment facilities. The relatively low hardening temperature (780–850°C) and oil quenching requirement make it accessible for many toolrooms. ### **Versatility:** From simple hand tools to complex dies, SKS2 serves well across a broad spectrum of cold work applications. Its balanced properties make it a "go-to" steel for many general-purpose tooling needs. ### **Final Recommendation:** JIS SKS2 remains a **highly relevant and widely used tool steel** for applications where its combination of machinability, dimensional stability during heat treatment, and good wear resistance at reasonable cost provides optimal value. For many cold work tooling applications, especially those involving complex geometries or where tool manufacturing efficiency is important, SKS2 continues to be an excellent choice that has stood the test of time in toolrooms worldwide. -:- For detailed product information, please contact sales. -: JIS SKS2 Oil-Hardening Cold Work Tool Steel Specification Dimensions Size： Diameter 20-1000 mm Length <6819 mm Size:We can customized as required Standard： Per your request or drawing We can customized as required Properties（Theoretical） Chemical Composition -:- For detailed product information, please contact sales. -: JIS SKS2 Oil-Hardening Cold Work Tool Steel Properties -:- For detailed product information, please contact sales. -:

Applications of JIS SKS2 Oil-Hardening Cold Work Tool Steel -:- For detailed product information, please contact sales. -: Chemical Identifiers JIS SKS2 Oil-Hardening Cold Work Tool Steel -:- For detailed product information, please contact sales. -:

Packing of JIS SKS2 Oil-Hardening Cold Work Tool Steel -:- For detailed product information, please contact sales. -: Standard Packing: -:- For detailed product information, please contact sales. -: Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 3290 gallon liquid totes Special package is available on request. E FORUs’ is carefully handled to minimize damage during storage and transportation and to preserve the quality of our products in their original condition