JIS SKT4 Low Alloy Tool Steel Rod/Bar

JIS SKT4 Low Alloy Tool Steel Rod Product Information -:- For detailed product information, please contact sales. -: JIS SKT4 Low Alloy Tool Steel Rod Synonyms -:- For detailed product information, please contact sales. -:

JIS SKT4 Low Alloy Tool Steel Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: JIS SKT4 Low-Alloy Tool Steel** ## **Overview** JIS SKT4 is a **nickel-chromium-molybdenum alloyed** steel classified under the Japanese Industrial Standards (JIS) system, belonging to the **SKT series (Alloy Tool Steels for Hot and Cold Work)**. Characterized by its **balanced composition of nickel, chromium, and molybdenum**, SKT4 offers excellent **toughness, hardenability, and wear resistance** for both hot and cold work applications. This versatile grade is particularly valued for its **good impact resistance and dimensional stability**, making it suitable for demanding tooling applications requiring reliable performance under varying service conditions. **Key Advantages:** - **Excellent Toughness:** Superior impact resistance and resistance to cracking - **Good Hardenability:** Deep hardening characteristics with minimal distortion - **Versatile Application:** Suitable for both hot and cold work tooling - **Good Wear Resistance:** Adequate carbide formation for moderate service conditions - **Machinability:** Good machining characteristics in annealed condition **Primary Considerations:** - Moderate wear resistance compared to specialized high-wear grades - Requires proper heat treatment to achieve optimal properties - Higher cost than simple alloy steels due to nickel content - Best performance in applications where toughness is prioritized ## **International Designations & Standards** | Standard System | Designation | Note | |----------------|-------------|------| | **JIS (Japan)** | SKT4 | Primary specification | | **ISO (International)** | ~**55NiCrMoV7** | Similar nickel-chromium-molybdenum steel | | **ASTM (USA)** | ~**L6** | Closest AISI equivalent (nickel-chromium tool steel) | | **DIN (Germany)** | ~1.2713 | Similar composition tool steel | | **BS (UK)** | ~**BH21** | Related alloy tool steel | | **GB (China)** | ~**5CrNiMo** | Similar hot work die steel | | **KS (Korea)** | ~**STD4** | Korean equivalent | *Note: SKT4 bridges hot and cold work applications with its balanced alloy content. International equivalents may vary in specific application focus.* --- ## **1. Chemical Composition (Typical, Weight %)** The nickel-chromium-molybdenum balance provides excellent toughness and hardenability. | Element | Content (%) | Role & Metallurgical Effect | |---------|-------------|-----------------------------| | **Carbon (C)** | 0.50 - 0.60 | Provides base hardness and strength while maintaining good toughness. Optimized for impact resistance. | | **Nickel (Ni)** | 1.00 - 1.50 | **Key alloying element.** Dramatically improves toughness, ductility, and hardenability. Enhances resistance to impact and thermal fatigue. | | **Chromium (Cr)** | 0.50 - 1.00 | Improves hardenability, wear resistance, and provides moderate oxidation resistance. | | **Molybdenum (Mo)** | 0.20 - 0.50 | Enhances hardenability, improves toughness, and increases high-temperature strength. | | **Manganese (Mn)** | 0.50 - 0.90 | Supports hardenability and promotes austenite stability. | | **Silicon (Si)** | 0.10 - 0.30 | Deoxidizer, provides solid solution strengthening. | | **Vanadium (V)** | ≤0.20 (Optional) | When present, refines grain size and improves toughness. | | **Phosphorus (P)** | ≤0.030 | Harmful impurity; kept low to prevent embrittlement. | | **Sulfur (S)** | ≤0.030 | Impurity; controlled for machinability. | | **Iron (Fe)** | Balance | Matrix element. | **Alloying Philosophy:** The moderate carbon content combined with nickel creates a steel with exceptional toughness, while chromium and molybdenum provide necessary hardenability and wear characteristics. --- ## **2. Physical & Mechanical Properties** ### **Physical Properties** | Property | Typical Value | Conditions/Notes | |----------|---------------|------------------| | **Density** | 7.83 - 7.85 g/cm³ | At 20°C (68°F) | | **Melting Range** | 1420 - 1440°C (2588 - 2624°F) | Liquidus to solidus range | | **Thermal Conductivity** | 42 - 46 W/m·K | At 20°C (68°F) | | **Specific Heat Capacity** | 460 - 480 J/kg·K | At 20°C (68°F) | | **Coefficient of Thermal Expansion** | 11.5 - 12.0 × 10⁻⁶/K | 20-200°C (68-392°F) range | | **Electrical Resistivity** | 0.30 - 0.35 μΩ·m | At 20°C (68°F) | | **Elastic Modulus** | 205 - 210 GPa (29.7 - 30.5 × 10⁶ psi) | At room temperature | ### **Mechanical Properties (Heat-Treated Condition)** | Property | Value Range | Heat Treatment Condition | |----------|-------------|--------------------------| | **Hardness (Annealed)** | 183 - 217 HB | Spheroidize annealed condition | | **Hardness (Hardened)** | 52 - 56 HRC | Oil quenched from 830-860°C, tempered at 400-500°C | | **Tensile Strength** | 1650 - 1850 MPa (239 - 268 ksi) | At 54-56 HRC | | **Yield Strength (0.2% offset)** | 1400 - 1600 MPa (203 - 232 ksi) | At 54-56 HRC | | **Impact Toughness (Charpy)** | 40 - 60 J (29.5 - 44.3 ft·lb) | At 54-56 HRC, unnotched – **Exceptional toughness** | | **Fatigue Endurance Limit** | 700 - 800 MPa (102 - 116 ksi) | Rotating bending, 10⁷ cycles | | **Compressive Strength** | 2000 - 2200 MPa (290 - 319 ksi) | At 54-56 HRC | | **Fracture Toughness (K₁c)** | 60 - 80 MPa√m | At 54-56 HRC – **Excellent for tool steel** | ### **Hardenability Characteristics** | Distance from Quenched End (Jominy, 1/16 in) | 1 | 4 | 8 | 12 | 16 | 20 | 24 | |---------------------------------------------|---|---|---|---|---|---|---| | **Hardness (HRC)** | 56-58 | 55-57 | 54-56 | 53-55 | 52-54 | 51-53 | 50-52 | **Section Hardening Capability:** - **50mm (2") diameter:** Through-hardened to 54-56 HRC - **100mm (4") diameter:** Surface 54-56 HRC, core 52-54 HRC - **150mm (6") diameter:** Surface 53-55 HRC, core 50-52 HRC - **200mm (8") diameter:** Surface 52-54 HRC, core 48-50 HRC *Excellent through-hardening capability due to nickel content.* --- ## **3. Product Applications** ### **Primary Application Areas** **1. Hot Work Applications:** - Hammer die blocks for forging - Hot forming dies and punches - Hot shear blades and trimming tools - Die casting die components (moderate temperature) **2. Cold Work Tooling:** - Heavy-duty forming dies - Cold heading dies and punches - Thread rolling dies for tough materials - Bending and forming tools **3. High-Impact Tools:** - Pneumatic tool components - Demolition tools and heavy chisels - Blacksmith tools and anvil tools - Machine tool components subject to shock **4. Mold Applications:** - Plastic injection molds for engineering resins - Compression molds for rubber - Glass mold components - Large mold bases and inserts ### **Industry-Specific Applications** | Industry | Typical SKT4 Components | |----------|-------------------------| | **Forging Industry** | Hammer dies, press dies, trimming dies | | **Metal Forming** | Heavy-duty forming tools, bending dies | | **Fastener Manufacturing** | Cold heading dies for large fasteners | | **Plastics Manufacturing** | Large injection mold bases, inserts | | **General Manufacturing** | Machine tool components, wear plates | ### **Service Performance Summary** | Application Condition | SKT4 Performance | Recommended Hardness | |----------------------|------------------|----------------------| | **High Impact/Shock** | Excellent | 52-54 HRC | | **Hot Work (to 400°C)** | Good | 48-52 HRC | | **Moderate Wear** | Good | 54-56 HRC | | **Fatigue Loading** | Excellent | 52-54 HRC | | **Precision Applications** | Good | 54-56 HRC | --- ## **4. Heat Treatment Guidelines** ### **Annealing (Preparation for Machining)** - **Process:** Full annealing or spheroidize annealing - **Temperature:** 800-830°C (1470-1525°F) - **Cooling:** Slow furnace cool at ≤20°C/hr to 550°C, then air cool - **Resulting Hardness:** 183-217 HB (Brinell) - **Microstructure:** Fine pearlite or spheroidized structure ### **Hardening (Austenitizing & Quenching)** 1. **Preheating:** Essential for this grade - Temperature: 550-650°C (1020-1200°F) - Time: 20-30 minutes per inch 2. **Austenitizing:** - **Temperature:** 830-860°C (1525-1580°F) - **Soaking Time:** 25-35 minutes per inch of thickness - **Atmosphere:** Neutral to slightly carburizing - **Grain Size:** ASTM 8-10 achievable 3. **Quenching:** - **Medium:** **Warm oil** (50-80°C / 120-175°F) - **Agitation:** Moderate to vigorous agitation - **Quench to:** 60-80°C (140-175°F) before tempering - **Note:** Can also use polymer quenchants for complex shapes ### **Tempering (Critical for Toughness)** - **Time to Temper:** Within 1-2 hours of quenching - **Standard Practice:** Double tempering strongly recommended - First temper: 400-500°C (750-930°F) for 2+ hours - Second temper: Same or slightly higher temperature, 2+ hours - **Temperature-Hardness Relationship:** - 200°C (400°F): 54-56 HRC - 300°C (570°F): 53-55 HRC - 400°C (750°F): 52-54 HRC - 500°C (930°F): 48-50 HRC - 550°C (1020°F): 44-46 HRC - 600°C (1110°F): 40-42 HRC ### **Special Heat Treatment for Hot Work** For hot work applications: - **Higher tempering temperatures:** 550-600°C (1020-1110°F) - **Resulting hardness:** 40-45 HRC - **Benefits:** Improved thermal fatigue resistance and dimensional stability at working temperatures --- ## **5. Machining & Fabrication** ### **Machinability (Annealed Condition)** - **Relative Machinability:** 65-70% (compared to 1% carbon steel = 100%) - **Cutting Tool Recommendations:** - **Carbide:** C2-C6 grades for general machining - **HSS:** M2 or better for difficult operations - **Cutting Parameters:** - **Turning:** 40-60 m/min (130-200 SFM) with carbide - **Milling:** 25-40 m/min (80-130 SFM) with carbide - **Drilling:** 15-25 m/min (50-80 SFM) with HSS - **Tool Geometry:** Positive rake angles recommended - **Coolant:** Soluble oil or emulsion ### **Grinding (Hardened Condition)** - **Wheel Selection:** Aluminum oxide (A46-J8-V) or CBN - **Parameters:** Moderate speed, light feed - **Coolant:** Ample flow to prevent overheating - **Note:** Grinds well due to moderate hardness ### **Welding Characteristics** - **Preheat:** 300-400°C (570-750°F) - **Post-Weld Heat Treatment:** Full re-hardening recommended - **Filler Metal:** Similar composition or austenitic stainless - **Applications:** Repair of tools and dies possible --- ## **6. Comparative Analysis** ### **vs. Other SKT Series Grades** | Property | SKT4 | SKT3 | SKT6 | SKD61 (Hot Work) | |----------|------|------|------|------------------| | **Nickel Content** | 1.00-1.50% | 0.20-0.50% | None | None | | **Primary Strength** | Toughness | Hot strength | Wear resistance | Hot hardness | | **Hot Work Capability** | Good | Very Good | Fair | Excellent | | **Impact Resistance** | Excellent | Good | Fair | Good | | **Typical Hardness** | 52-56 HRC | 48-52 HRC | 56-60 HRC | 48-52 HRC | ### **vs. International Equivalents** | Aspect | JIS SKT4 | AISI L6 | DIN 1.2713 | 55NiCrMoV7 | |--------|----------|---------|------------|-------------| | **Nickel Content** | 1.00-1.50% | 1.25-1.75% | 0.90-1.20% | 1.50-1.80% | | **Primary Application** | Impact tools | General tooling | Forging dies | Forging dies | | **Toughness Level** | High | Very High | High | High | | **Hot Work Use** | Yes | Limited | Yes | Yes | | **Cost Factor** | 1.0x | 1.1x | 1.1x | 1.2x | --- ## **7. Quality Control & Inspection** ### **Material Specifications** - **Decarburization:** Maximum 0.15mm per side on tooling stock - **Surface Quality:** Free from seams, laps, and cracks - **Ultrasonic Testing:** Available for large die blocks - **Dimensions:** Per JIS G4404 requirements ### **Testing Requirements** - **Chemical Analysis:** Full spectrographic analysis - **Hardness Testing:** Multiple points for large sections - **Impact Testing:** Charpy testing for critical applications - **Microstructure:** Grain size and inclusion rating --- ## **8. Technical Recommendations** ### **Design Guidelines** 1. **Section Transitions:** Use generous radii (minimum R3mm) 2. **Wall Thickness:** Maintain uniformity where possible 3. **Hardness Selection:** Choose based on primary service condition 4. **Surface Finish:** Critical surfaces 1.6-3.2μm Ra ### **Heat Treatment Best Practices** 1. **Temperature Uniformity:** Ensure even heating in furnace 2. **Quench Control:** Maintain oil temperature and agitation 3. **Tempering:** Always double temper for best toughness 4. **Record Keeping:** Document all parameters for traceability ### **Common Issues and Solutions** | Problem | Likely Cause | Corrective Action | |---------|--------------|-------------------| | **Insufficient Toughness** | Low tempering temperature | Increase tempering temperature | | **Excessive Wear** | Too low hardness | Decrease tempering temperature | | **Distortion** | Uneven heating/quenching | Improve fixturing, use preheat | | **Cracking in Service** | Design stress concentrations | Increase radii, improve design | ### **Safety Considerations** - **Heat Treatment:** Standard furnace and oil safety procedures - **Machining:** Nickel alloys may require dust control - **Handling:** Large tools require proper lifting equipment - **Storage:** Protect from corrosion in humid environments --- ## **Disclaimer** This technical datasheet provides general information about JIS SKT4 tool steel based on standard specifications and industry practices. Actual properties and performance may vary depending on: 1. **Manufacturer's specific production methods** and quality control 2. **Precise heat treatment parameters** and equipment used 3. **Specific application conditions** and service requirements 4. **Tool design, manufacturing quality,** and maintenance practices **Important Considerations:** - SKT4 is a versatile steel but not optimal for extreme wear or high-temperature applications - Proper heat treatment is essential for achieving the desired toughness - Consider specialized grades for single-purpose applications - Always conduct testing for critical applications For current specifications and detailed technical data, refer to: - JIS G4404: Tool Steels - Manufacturer's technical datasheets and recommendations - Applicable industry standards and best practices This information is intended for reference purposes and is subject to revision as standards and technology evolve. Users should verify specific requirements with their steel suppliers and technical consultants for critical applications. -:- For detailed product information, please contact sales. -: JIS SKT4 Low Alloy Tool Steel Specification Dimensions Size： Diameter 20-1000 mm Length <6714 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 SKT4 Low Alloy Tool Steel Properties -:- For detailed product information, please contact sales. -:

Applications of JIS SKT4 Low Alloy Tool Steel Rod -:- For detailed product information, please contact sales. -: Chemical Identifiers JIS SKT4 Low Alloy Tool Steel Rod -:- For detailed product information, please contact sales. -:

Packing of JIS SKT4 Low Alloy Tool Steel Rod -:- 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 Rod 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 3185 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