JIS SKH59 Molybdenum High Speed Tool Steel Sheet,Plate

JIS SKH59 Molybdenum High Speed Tool Steel Sheet/Plate Product Information -:- For detailed product information, please contact sales. -: JIS SKH59 Molybdenum High Speed Tool Steel Sheet/Plate Synonyms -:- For detailed product information, please contact sales. -:

JIS SKH59 Molybdenum High Speed Tool Steel Product Information -:- For detailed product information, please contact sales. -: # **JIS SKH59 Molybdenum High-Speed Tool Steel** **International Standard:** JIS G4403 (Japan Industrial Standard) - High-Speed Tool Steels --- ## **1. Overview** JIS SKH59 is an **ultra-high-performance cobalt-molybdenum high-speed steel** that represents the pinnacle of conventional high-speed steel technology within the JIS classification system. Characterized by its **exceptionally high cobalt content (approximately 10-12%) balanced with optimized vanadium and carbon**, this grade is designed for the most extreme machining applications where maximum red hardness and hot strength are paramount. SKH59 is engineered to maintain cutting edge integrity under the severest thermal and mechanical stresses encountered in modern high-speed machining of superalloys, hardened steels, and other difficult-to-machine materials. --- ## **2. Chemical Composition (Typical Weight %)** | Element | Content (%) | | :------ | :---------- | | C | 1.25–1.40 | | Si | 0.15–0.45 | | Mn | 0.15–0.40 | | Cr | 3.80–4.50 | | Mo | 8.50–9.50 | | W | 5.50–6.50 | | V | 2.80–3.30 | | Co | 10.0–12.0 | | P (max) | 0.030 | | S (max) | 0.030 | **Balance:** Iron (Fe). **Key Characteristics:** SKH59 combines **ultra-high cobalt (10-12%) with significant vanadium (2.8-3.3%)** and **elevated molybdenum content**. This creates a highly alloyed matrix where cobalt provides exceptional solid solution strengthening and thermal properties, while vanadium carbides deliver excellent wear resistance. The carbon content is precisely balanced to optimize both carbide formation and matrix properties. --- ## **3. Physical & Mechanical Properties** ### **Physical Properties** - **Density:** ~8.20 g/cm³ - **Thermal Conductivity:** **Excellent** – Exceptionally high due to cobalt content (~33-38 W/m·K at 20°C), facilitating superior heat dissipation - **Coefficient of Thermal Expansion:** ~11.2 ×10⁻⁶ /K (20–500°C) - **Specific Heat Capacity:** ~0.46 kJ/kg·K - **Magnetic Properties:** Strongly ferromagnetic - **Electrical Conductivity:** Relatively good for a tool steel due to cobalt content ### **Mechanical Properties (Heat-Treated)** - **Annealed Hardness:** ≤ 302 HB - **Hardened & Tempered Hardness:** **68–70+ HRC** (consistently achieves ultra-high hardness levels) - **Red Hardness:** **Superior** – Maintains effective hardness up to ~670-690°C - **Hot Hardness at 600°C:** ~60-62 HRC (among highest for conventional HSS) - **Hot Hardness at 650°C:** ~55-57 HRC (exceptional retention) - **Wear Resistance:** **Excellent** – High vanadium content provides substantial abrasion resistance - **Transverse Rupture Strength:** 2,600–3,100 MPa - **Compressive Strength:** 3,700–4,300 MPa - **Modulus of Elasticity:** ~210 GPa - **Toughness:** **Moderate** – Better than expected for its hardness due to cobalt-enhanced matrix ductility --- ## **4. Heat Treatment Specifications** ### **1. Annealing** - **Full Annealing Temperature:** 850–900°C - **Process:** Heat uniformly, hold for 3–4 hours, furnace cool slowly (10–15°C/h) to 600°C, air cool - **Resulting Hardness:** ≤ 302 HB - **Spheroidize Annealing:** Highly recommended for optimal carbide spheroidization and machinability ### **2. Stress Relieving** - **Temperature:** 600–650°C - **Hold Time:** 2–3 hours per 25mm thickness - **Cooling:** Slow furnace cool or air cool - **Purpose:** Critical for complex tools to minimize distortion during final hardening ### **3. Hardening (Quenching)** - **Preheating:** **Multi-stage critical process:** - **First Preheat:** 450–550°C (ensure through-heating) - **Second Preheat:** 800–850°C (equalize temperature) - **Austenitizing Temperature:** **1200–1230°C** (Precise control essential) - **Soaking Time:** 2–4 minutes per 25mm section (minimum effective time) - **Quenching Medium:** Oil (preferred), hot salt bath (500-550°C for complex tools), or air for simple shapes ### **4. Tempering** - **Immediate Tempering:** Must begin when tool reaches 50–80°C - **Temperature Range:** 540–590°C - **Cycle:** **Triple tempering mandatory** – Each cycle: 2+ hours, air cool completely between cycles - **Optimal Process:** Temper at 560–580°C three times - **Hardness Development:** Exhibits strong secondary hardening; typically achieves 69–70+ HRC ### **5. Sub-Zero Treatment** - **Highly Recommended:** -80 to -100°C between quenching and first temper - **Duration:** 2–4 hours - **Benefits:** Maximizes transformation of retained austenite, improves dimensional stability, increases final hardness --- ## **5. Key Features & Advantages** 1. **Ultimate Red Hardness:** Ultra-high cobalt content provides exceptional hardness retention at extreme temperatures, outperforming most commercial HSS grades 2. **Superior Hot Strength:** Maintains cutting edge integrity under the most severe thermal loads 3. **Excellent Thermal Conductivity:** Enhanced heat dissipation reduces thermal damage, allows higher cutting parameters 4. **High Wear Resistance:** Significant vanadium content provides excellent resistance to abrasive wear 5. **Optimal Hardness-Toughness Balance:** Cobalt-enhanced matrix provides better toughness than expected for its hardness level 6. **Exceptional Thermal Fatigue Resistance:** Withstands repeated thermal cycling better than lower-cobalt grades **Trade-offs:** - **Very High Cost:** Extremely high cobalt content makes it among the most expensive HSS grades - **Specialized Application Range:** Not suitable for interrupted cuts or impact loading - **Complex Processing:** Demands precise heat treatment control and expertise - **Limited Availability:** Produced in limited quantities due to specialized nature --- ## **6. Typical Applications** SKH59 is reserved for the **most extreme machining applications** where thermal resistance is the primary limiting factor and cost is secondary to performance. ### **Primary Cutting Tool Applications:** #### **Aerospace & Power Generation:** - **Nickel-based Superalloys:** Inconel 718, 625, 713, Rene series, Hastelloy - **Cobalt-based Alloys:** Stellite, Haynes alloys - **Titanium Alloys:** Ti-6Al-4V, Ti-10V-2Fe-3Al, beta titanium alloys - **High-Temperature Stainless Steels:** A286, 17-4PH, 15-5PH in hardened condition #### **Hardened Materials:** - **Tool & Die Steels:** Hardened to 50-65 HRC - **Bearing Steels:** 52100, M50, other high-carbon steels - **High-Strength Alloys:** 300M, 4340, 4140 in hardened condition - **Die Casting Dies:** H13, H11 in hardened condition #### **Specific Tool Types:** - **High-Performance End Mills:** For aerospace structural components - **Solid Carbide Drills & Reamers:** Alternative where higher toughness than carbide is required - **Thread Mills & Taps:** For precision threading in superalloys - **Broaches:** For finishing turbine disks and other critical components - **Gear Hobs & Shapers:** For manufacturing hardened aerospace gears - **Form Tools & Inserts:** For specialized profiling operations ### **Specialized Industrial Sectors:** #### **Aerospace Manufacturing:** - Jet engine components (disks, blades, shafts) - Landing gear components - Structural airframe parts - Space vehicle components #### **Power Generation:** - Gas turbine components - Steam turbine blades and disks - Nuclear reactor components - High-temperature valve systems #### **High-Performance Automotive:** - Racing engine components - High-stress transmission parts - Performance suspension components #### **Oil & Gas:** - Downhole drilling tools - Valve components for high-pressure/high-temperature service - Subsea equipment components --- ## **7. International Standard Equivalents** | Standard | Grade Designation | Notes | | :--------------- | :------------------ | :----------------------------------------- | | **JIS** | SKH59 | Original specification (JIS G4403) | | **Proprietary** | Various high-Co HSS | Similar grades from major producers (e.g., special high-Co variants of M42/M48) | | **Custom Grades**| Ultra-high Co HSS | Manufacturer-specific formulations | | **Comparative** | Performance similar to premium PM-HSS | Though different manufacturing route | **Note:** SKH59 represents a **specialized ultra-high-cobalt grade** without direct universal equivalents. It embodies the highest performance level in conventional JIS HSS classification and is typically used for specific critical applications in Japanese high-tech industries. --- ## **8. Machining & Fabrication Guidelines** ### **Machining (In Annealed State):** - **Challenging Machinability:** High carbide content and hardness require careful approach - **Tooling:** **Premium carbide tools essential** – Use micrograin or submicron grades - **Parameters:** Conservative speeds (30-50% of standard steel rates), moderate feeds - **Coolant:** High-pressure coolant systems recommended - **Chip Control:** Use chipbreakers and positive rake angles ### **Grinding:** - **Critical Success Factor:** Proper technique determines final tool performance - **Wheel Selection:** - **Optimal:** Cubic Boron Nitride (CBN) wheels – most efficient and controllable - **Alternative:** High-quality diamond wheels for certain geometries - **Conventional:** Premium ceramic aluminum oxide wheels (soft grade, open structure) - **Parameters:** - **Infeed:** 0.005-0.015 mm/pass (finish), 0.02-0.05 mm/pass (roughing) - **Wheel Speed:** 25-35 m/s for conventional wheels, 80-120 m/s for CBN - **Workpiece Speed:** 10-20 m/min - **Coolant:** Copious high-pressure coolant (minimum 2-3 bar) essential - **Wheel Dressing:** Frequent dressing (every 2-4 parts for precision tools) - **Thermal Management:** Critical to avoid grinding burns (>0.5 mm affected zone unacceptable) ### **Electrical Discharge Machining (EDM):** - **Effective Method:** For complex geometries in hardened state - **Parameters:** - **Roughing:** High current, long pulse duration - **Finishing:** Multiple passes with decreasing parameters - **Final Pass:** Very fine settings for best surface integrity - **Post-EDM Processing:** - **Mandatory:** Complete removal of white layer (0.02-0.10 mm typically) - **Methods:** Diamond grinding, abrasive flow machining, ultrasonic polishing - **Stress Relief:** Low-temperature tempering (300-400°C) recommended ### **Wire EDM:** - **Excellent for:** Profile cutting of hardened blanks - **Considerations:** - **Cutting Speed:** 30-50% slower than for lower-alloy steels - **Wire Type:** Coated or stratified wires recommended - **Flushing:** High-pressure dielectric essential --- ## **9. Surface Treatment & Enhancement** ### **1. PVD Coatings (Primary Enhancement):** - **Optimal Coatings:** - **TiAlN/AlTiN:** Excellent thermal barrier properties - **AlCrN:** Superior oxidation resistance at high temperatures - **TiSiN:** Ultra-hard nanocomposite coating - **DLC:** For non-ferrous applications - **Coating Thickness:** 2-5 μm optimal - **Application Temperature:** 400-500°C (below tempering temperature) - **Performance Improvement:** Typically 3-8× tool life improvement in appropriate applications ### **2. CVD Coatings:** - **For Specific Applications:** TiCN/Al₂O₃/TiN multilayer systems - **Application Temperature:** 900-1050°C (requires special substrate treatment) - **Considerations:** May affect core properties; used primarily for inserts ### **3. Nitriding:** - **Process:** Plasma nitriding at 480–520°C - **Case Depth:** 0.02–0.08 mm - **Surface Hardness:** 1200–1500 HV - **Benefits:** Improved wear resistance without affecting core properties - **Limitations:** Temperature must remain below final tempering temperature ### **4. Surface Engineering:** - **Laser Surface Texturing:** - **Patterns:** Micro-dimples, grooves, cross-hatching - **Benefits:** Improved chip evacuation, reduced cutting forces, better lubricant retention - **Micro-blasting:** - **Media:** Ceramic or glass beads - **Benefits:** Controlled edge preparation, induced compressive stresses - **Electropolishing:** - **Benefits:** Improved surface finish, reduced adhesion tendency --- ## **10. Quality Control & Certification** ### **Material Certification:** - **Full Chemical Analysis:** Each heat with emphasis on Co, V, Mo, C balance - **Microcleanliness:** Per ASTM E45 (maximizing cleanliness for critical applications) - **Carbide Analysis:** - Size distribution (maximum 5-8 μm preferred) - Morphology (spheroidized preferred) - Distribution uniformity ### **Heat Treatment Validation:** - **Hardness Mapping:** Multiple points across critical sections - **Microstructure Examination:** - Grain size (ASTM 9 or finer required) - Tempered martensite quality - Retained austenite content (<3% desired) - **Dimensional Stability:** Verification after multiple tempering cycles ### **Non-Destructive Testing:** - **Ultrasonic Testing:** For internal soundness in larger sections - **Magnetic Particle Inspection:** For surface and near-surface defects - **Dye Penetrant Inspection:** For surface-breaking defects - **Dimensional Verification:** Post-heat treatment for critical tools ### **Performance Testing (Selective):** - **Hot Hardness Testing:** At 600°C and 650°C - **Wear Testing:** Pin-on-disk or turning tests against standard materials - **Thermal Fatigue Testing:** For tools subjected to cycling conditions --- ## **11. Economic & Strategic Considerations** ### **Cost Analysis:** - **Raw Material Cost:** Extremely high (typically 5-8× M2 cost) - **Processing Cost:** 2-3× higher than standard HSS due to specialized handling - **Tool Life:** 3-10× longer than M42 in appropriate applications - **Productivity Gains:** Enables 20-50% higher cutting speeds - **Downtime Reduction:** Fewer tool changes increase machine utilization ### **Return on Investment Factors:** - **Justified When:** - Machining costs significantly exceed tool costs - Tool failure has severe safety or quality consequences - Production bottlenecks exist due to tool life limitations - High-value components are being manufactured - **ROI Calculation Considerations:** - Total cost per part (including tooling) - Machine hour rate savings - Scrap/rework reduction - Delivery time improvements ### **Supply Chain Considerations:** - **Limited Suppliers:** Only specialized mills produce such grades - **Lead Times:** Typically 12-24 weeks for custom orders - **Minimum Quantities:** Higher than standard grades - **Quality Assurance:** Requires extensive supplier qualification --- ## **12. Performance Comparison** ### **Within JIS High-Speed Steel Family:** | Property | SKH59 | SKH58 | SKH57 | SKH55 (M42) | |-----------------------|--------------|--------------|--------------|--------------| | **Cobalt Content** | 10–12% | 7.5–8.5% | 11.5–12.5% | 8–9% | | **Vanadium Content** | 2.8–3.3% | 3.0–3.5% | 2.8–3.3% | 1.0–1.25% | | **Red Hardness** | **Best** | Very Good | Excellent | Excellent | | **Wear Resistance** | Excellent | **Best** | Excellent | Very Good | | **Hot Hardness (650°C)** | ~56 HRC | ~53 HRC | ~55 HRC | ~54 HRC | | **Toughness** | Moderate | Moderate | Moderate | Low-Moderate | | **Thermal Conductivity** | **Best** | Very Good | Excellent | Good | | **Cost Factor** | Highest | High | Highest | High | ### **Compared to Alternative Technologies:** | Property | SKH59 | PM-HSS | Carbide | Ceramic | |-----------------------|--------------|---------------|---------------|--------------| | **Red Hardness** | Excellent | Excellent | Good | **Best** | | **Toughness** | **Best** | Good | Poor | Very Poor | | **Wear Resistance** | Excellent | **Best** | Excellent | Excellent | | **Grindability** | Good | Poor | N/A | N/A | | **Cost** | High | Very High | Moderate | High | | **Optimal Speed Range**| Medium-High | High | Medium | **Very High**| --- ## **13. Summary & Selection Guidelines** JIS SKH59 represents the **ultimate in conventional high-speed steel performance**, pushing the boundaries of what is achievable with wrought high-alloy tool steel technology. ### **Select SKH59 When:** 1. **Maximum Red Hardness** is the primary requirement 2. Machining **superalloys, titanium, or hardened steels** at the highest feasible speeds 3. **Cutting edge temperatures regularly exceed 650°C** 4. **Thermal softening** is the dominant failure mode of current tools 5. **Dry or high-speed machining** operations demand ultimate heat resistance 6. **Productivity gains** justify substantial material cost premiums 7. **Conventional HSS processing** is required or preferred over PM alternatives ### **Avoid SKH59 When:** 1. Applications involve **significant interruption or impact** 2. **Cost sensitivity** outweighs performance benefits 3. **Lower-cobalt grades** (M42, M48) provide adequate performance 4. **Heat treatment capabilities** are limited 5. **Powder metallurgy HSS** could provide better overall value 6. **Carbide or ceramic tools** are more appropriate for the application ### **Strategic Applications:** - **Mission-critical aerospace components:** Where reliability is paramount - **High-volume production** of difficult materials where tool life dictates cycle time - **Prototype and development work** on new difficult-to-machine materials - **Specialized tooling** for unique or proprietary machining processes ### **Future Outlook:** While powder metallurgy (PM) HSS continues to advance, SKH59 maintains relevance for applications where: - **Conventional HSS manufacturing processes** are well-established - **Specific wrought material characteristics** are required - **Cobalt's unique benefits** are maximized for particular applications - **The full hardness potential** of conventional HSS is needed without PM processing ### **Implementation Strategy:** 1. **Start with Testing:** Conduct controlled trials comparing SKH59 to current tools 2. **Focus on Critical Operations:** Implement initially on bottleneck operations 3. **Optimize Parameters:** Adjust speeds, feeds, and cooling for maximum benefit 4. **Monitor Performance:** Track tool life, surface finish, and dimensional accuracy 5. **Calculate True Costs:** Include all factors in ROI analysis ### **Final Recommendation:** SKH59 should be considered a **strategic specialty material** for the most demanding applications rather than a general-purpose tool steel. Its use should be justified by specific performance requirements that cannot be met by lower-cost alternatives. When applied correctly to appropriate challenges, SKH59 delivers unparalleled high-temperature performance that can transform the economics of machining the world's most difficult materials. For manufacturers pushing the boundaries of machining technology in aerospace, power generation, and other high-tech industries, SKH59 represents a **proven, ultra-high-performance option** that continues to offer strategic value in the most demanding industrial applications. Its combination of extreme red hardness, good toughness, and reliable performance makes it a critical material in the advanced manufacturing toolkit for those who need the absolute best in conventional high-speed steel technology. -:- For detailed product information, please contact sales. -: JIS SKH59 Molybdenum High Speed Tool Steel Specification Dimensions Size： Diameter 20-1000 mm Length <6818 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 SKH59 Molybdenum High Speed Tool Steel Properties -:- For detailed product information, please contact sales. -:

Applications of JIS SKH59 Molybdenum High Speed Tool Steel Sheet,Plate -:- For detailed product information, please contact sales. -: Chemical Identifiers JIS SKH59 Molybdenum High Speed Tool Steel Sheet,Plate -:- For detailed product information, please contact sales. -:

Packing of JIS SKH59 Molybdenum High Speed Tool Steel Sheet/Plate -:- 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 Sheet/Plate 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 3289 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