JIS SKH58 Molybdenum High Speed Tool Steel Sheet,Plate

JIS SKH58 Molybdenum High Speed Tool Steel Sheet/Plate Product Information -:- For detailed product information, please contact sales. -: JIS SKH58 Molybdenum High Speed Tool Steel Sheet/Plate Synonyms -:- For detailed product information, please contact sales. -:

JIS SKH58 Molybdenum High Speed Tool Steel Product Information -:- For detailed product information, please contact sales. -: # **JIS SKH58 Molybdenum High-Speed Tool Steel** **International Standard:** JIS G4403 (Japan Industrial Standard) - High-Speed Tool Steels --- ## **1. Overview** JIS SKH58 is a **premium high-vanadium, cobalt-bearing molybdenum-based high-speed steel** that represents a specialized balance of extreme wear resistance and good high-temperature performance. Characterized by its **exceptionally high vanadium content combined with substantial cobalt addition**, this grade is engineered for applications where abrasion is the primary wear mechanism, yet some degree of red hardness is still required. SKH58 occupies a unique position between ultra-high-wear-resistant grades like SKH53 (M3:2) and high-cobalt hot-hardness grades like SKH55 (M42), offering a distinct combination for specific machining challenges. --- ## **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 | 4.80–5.50 | | W | 5.90–6.70 | | V | 3.00–3.50 | | Co | 7.50–8.50 | | P (max) | 0.030 | | S (max) | 0.030 | **Balance:** Iron (Fe). **Key Characteristics:** SKH58 combines **very high vanadium (3.0-3.5%) with substantial cobalt (7.5-8.5%)**, creating a unique alloy that delivers both excellent abrasion resistance (from vanadium carbides) and improved red hardness (from cobalt). The carbon content is elevated to match the high vanadium content, ensuring adequate carbon for carbide formation without excessive free carbon. --- ## **3. Physical & Mechanical Properties** ### **Physical Properties** - **Density:** ~8.15 g/cm³ - **Thermal Conductivity:** **Good** – Enhanced by cobalt content (~26-29 W/m·K at 20°C), better than high-vanadium, low-cobalt grades - **Coefficient of Thermal Expansion:** ~11.3 ×10⁻⁶ /K (20–500°C) - **Specific Heat Capacity:** ~0.46 kJ/kg·K - **Magnetic Properties:** Ferromagnetic ### **Mechanical Properties (Heat-Treated)** - **Annealed Hardness:** ≤ 293 HB - **Hardened & Tempered Hardness:** **66–69 HRC** (can achieve 68-69 HRC with optimized treatment) - **Red Hardness:** **Very Good to Excellent** – Maintains hardness effectively up to ~620-640°C - **Hot Hardness at 600°C:** ~56-58 HRC (improved over standard high-V grades due to cobalt) - **Wear Resistance:** **Exceptional** – Among the highest for conventional HSS due to high vanadium carbide volume - **Transverse Rupture Strength:** 2,700–3,100 MPa - **Compressive Strength:** 3,500–4,000 MPa - **Toughness:** **Moderate** – Lower than low-vanadium grades but better than some ultra-high-V grades due to cobalt matrix strengthening --- ## **4. Heat Treatment Specifications** ### **1. Annealing** - **Temperature:** 850–900°C - **Process:** Heat uniformly, hold for 3–4 hours, furnace cool slowly (10–15°C/h) to 600°C, then air cool - **Resulting Hardness:** ≤ 293 HB - **Spheroidize Annealing:** Recommended to optimize carbide morphology ### **2. Stress Relieving** - **Temperature:** 600–650°C - **Hold Time:** 2 hours per 25mm thickness - **Purpose:** Particularly important due to high alloy content and potential for distortion ### **3. Hardening (Quenching)** - **Preheating:** **Critical multi-stage process:** - **First Preheat:** 450–550°C - **Second Preheat:** 800–850°C - **Austenitizing Temperature:** **1190–1220°C** (Upper range often used to dissolve vanadium carbides) - **Soaking Time:** 2–4 minutes per 25mm section (adequate time needed for carbide solutioning) - **Quenching Medium:** Oil quenching recommended; salt bath for complex tools ### **4. Tempering** - **Immediate Tempering Required:** Begin when tool reaches 50–80°C - **Temperature Range:** 540–580°C - **Cycle:** **Triple tempering strongly recommended** – Each cycle: 2 hours minimum, air cool completely - **Optimal Process:** Temper at 560–570°C three times - **Hardness Development:** Strong secondary hardening response; achieves 67–69 HRC ### **5. Sub-Zero Treatment** - **Recommended:** Treatment at -70 to -100°C between quenching and first temper - **Benefits:** Particularly effective for stabilizing dimensions in high-alloy tools --- ## **5. Key Features & Advantages** 1. **Extreme Wear/Abrasion Resistance:** The high vanadium content (3.0-3.5%) provides exceptional resistance to abrasive wear, superior to most conventional HSS grades 2. **Enhanced Red Hardness:** Cobalt addition (7.5-8.5%) improves high-temperature performance compared to non-cobalt high-vanadium grades 3. **Balanced Performance:** Offers a unique combination of wear resistance and hot hardness not found in standard grades 4. **Good High-Temperature Strength:** Maintains cutting edge integrity under combined thermal and abrasive conditions 5. **Optimized for Specific Applications:** Designed for materials that are both abrasive and generate significant cutting heat **Trade-offs:** - **High Cost:** Significant cobalt and vanadium content makes it expensive - **Reduced Toughness:** Not suitable for severe interrupted cuts - **Challenging Grindability:** Hard vanadium carbides make grinding more difficult - **Complex Heat Treatment:** Requires precise control to optimize properties --- ## **6. Typical Applications** SKH58 is designed for **specialized applications where both abrasion and heat are significant factors**. ### **Primary Cutting Tool Applications:** - **Machining Highly Abrasive Materials at Higher Speeds:** - Advanced composites (carbon fiber, glass fiber, aramid composites) - High-silicon aluminum alloys (16-22% Si) at elevated cutting speeds - Metal matrix composites (MMCs) - Abrasive plastics with fillers (glass-filled, mineral-filled polymers) - Hardened steels with abrasive inclusions - **Specific Tool Types:** - **End Mills for Composites:** Where both abrasion and heat from high spindle speeds are concerns - **Drills for Abrasive Materials:** Requiring extended tool life in production environments - **Routers and Trimmers:** For composite material machining - **Broaches:** For finishing abrasive components where dimensional stability is critical - **Gear Hobs:** For cutting abrasive materials or gears with abrasive coatings ### **Specialized Industrial Applications:** - **Aerospace Composite Manufacturing:** Machining CFRP, GFRP structural components - **Automotive:** Machining aluminum-silicon alloy engine blocks and components - **Electronics:** Machining abrasive composite enclosures and components - **Mold & Die:** For molds processing abrasive filled plastics ### **Wear Part Applications:** - **Specialized Wear Components:** Where both abrasion and moderate temperatures are factors - **Guides and Bushings:** In abrasive processing environments - **Punches and Dies:** For forming abrasive materials --- ## **7. International Standard Equivalents** | Standard | Grade Designation | Notes | | :--------------- | :------------------ | :----------------------------------------- | | **JIS** | SKH58 | Original specification (JIS G4403) | | **AISI/SAE (USA)**| Similar to M4+Co* | High-vanadium, cobalt-bearing variant | | **Custom/Proprietary** | Various | Similar high-V, high-Co grades from specialty producers | | **DIN (Germany)** | Special grades | Comparable high-performance HSS | | **GB (China)** | Special grades | Custom formulations for specific needs | **Note:** SKH58 does not have a direct, universally standardized equivalent. It represents a specialized Japanese industrial grade that combines features of both high-vanadium (for wear) and high-cobalt (for hot hardness) HSS types. --- ## **8. Machining & Fabrication Guidelines** ### **Machining (In Annealed State):** - **Challenging Machinability:** Hard carbides and relatively high annealed hardness - **Tooling:** **Carbide tools essential** – Use grades for hard, abrasive materials - **Parameters:** Moderate speeds, consistent feeds, ample coolant - **Work Hardening:** Minimize tool dwell to prevent work hardening ### **Grinding:** - **Critical Consideration:** Hard vanadium carbides present grinding challenges - **Wheel Selection:** - **Optimal:** Cubic Boron Nitride (CBN) wheels – most efficient - **Alternative:** Diamond wheels for certain operations - **Conventional:** Premium ceramic aluminum oxide wheels with soft grade - **Parameters:** Light infeeds, high wheel speeds, copious high-pressure coolant - **Wheel Dressing:** Frequent dressing essential for maintaining efficiency - **Thermal Management:** Critical to avoid thermal damage ### **Electrical Discharge Machining (EDM):** - **Effective Method:** Suitable for complex shapes - **Parameters:** Use multiple passes with fine finish settings - **Post-Processing:** **Mandatory** removal of white layer - **Stress Relief:** Low-temperature tempering recommended ### **Wire EDM:** - **Suitable:** For profile cutting of hardened stock - **Considerations:** May require optimized parameters for best results --- ## **9. Surface Treatment** SKH58 benefits significantly from advanced surface treatments: 1. **PVD Coatings:** - **Recommended:** TiAlN, AlCrN, TiSiN, AlTiN - **Benefits:** Enhanced surface hardness, thermal barrier, reduced friction - **Application:** After final polishing; typical thickness 2-4 μm 2. **CVD Coatings:** - **For Specific Needs:** TiCN-based multilayer systems - **Consideration:** Higher temperature process requires careful control 3. **Nitriding:** - **Process:** Plasma or gas nitriding at 480–520°C - **Case Depth:** 0.03–0.10 mm - **Surface Hardness:** 1200–1400 HV - **Caution:** Temperature control critical 4. **Surface Engineering:** - **Laser Texturing:** For improved chip control - **Micro-blasting:** For edge preparation --- ## **10. Performance Comparison** ### **Within High-Speed Steel Categories:** | Property | SKH58 | SKH53 (M3:2) | SKH55 (M42) | SKH56 | |-----------------------|--------------|--------------|--------------|--------------| | **Vanadium Content** | 3.0–3.5% | 2.4–2.8% | 1.0–1.25% | 3.5–4.25% | | **Cobalt Content** | 7.5–8.5% | <0.5% | 8.0–9.0% | 9.5–10.5% | | **Wear Resistance** | **Excellent** | Very Good | Good | **Best** | | **Red Hardness** | Very Good | Good | **Excellent** | Excellent | | **Toughness** | Moderate | Moderate | Low-Moderate | Low | | **Primary Strength** | Abrasion | Abrasion | Heat | Both | ### **Strategic Positioning:** - **Compared to SKH53 (M3:2):** Better high-temperature performance due to cobalt - **Compared to SKH55 (M42):** Better wear resistance due to higher vanadium - **Compared to SKH56:** More balanced between wear and heat resistance - **Unique Niche:** For applications needing both abrasion resistance and moderate hot hardness --- ## **11. Quality Control** ### **Material Certification:** - Full chemical analysis with emphasis on V, Co, C balance - Microcleanliness assessment - Carbide structure analysis ### **Heat Treatment Validation:** - Hardness uniformity testing - Microstructure examination - Dimensional stability verification ### **Non-Destructive Testing:** - Ultrasonic inspection - Magnetic particle inspection - Dimensional accuracy verification --- ## **12. Economic Considerations** ### **Cost Factors:** - **Raw Material:** High due to vanadium and cobalt content - **Processing:** Higher grinding and heat treatment costs - **Tool Life:** Extended life in appropriate applications - **Productivity:** Enables efficient machining of difficult materials ### **ROI Justification:** - When machining highly abrasive materials - When both abrasion and heat are limiting factors - For critical production operations - When alternative materials fail prematurely --- ## **13. Summary & Selection Guidelines** JIS SKH58 represents a **specialized high-performance HSS grade** that fills a specific niche between pure abrasion-resistant grades and pure hot-hardness grades. **Select SKH58 when:** 1. Machining **highly abrasive materials** that also generate significant heat 2. **Both flank wear and thermal softening** are observed as failure modes 3. **Higher cutting speeds** are desired on abrasive materials 4. **Existing high-V tools** fail due to thermal issues 5. **Existing high-Co tools** fail due to abrasive wear **Optimal Application Examples:** - High-speed routing of carbon fiber composites - Drilling high-silicon aluminum at elevated speeds - Machining metal matrix composites in production quantities - Operations where switching between different tool materials is impractical **Alternative Considerations:** - **For pure abrasion:** Consider SKH53 (M3:2) or higher V grades - **For pure hot hardness:** Consider SKH55 (M42) or higher Co grades - **For extreme both:** Consider SKH56 or powder metallurgy grades - **For cost-sensitive applications:** Consider whether SKH51 (M2) with coating might suffice **Strategic Value:** SKH58 provides a **balanced solution** for specific industrial challenges where both abrasion and heat resistance are required. While not as extreme in either property as specialized grades, its balanced approach makes it versatile for certain production environments. For manufacturers facing **combined abrasive and thermal challenges** in their machining operations, SKH58 offers a **technologically advanced solution** that can improve tool life, reduce changeover frequency, and increase overall productivity in appropriate applications. -:- For detailed product information, please contact sales. -: JIS SKH58 Molybdenum High Speed Tool Steel Specification Dimensions Size： Diameter 20-1000 mm Length <6817 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 SKH58 Molybdenum High Speed Tool Steel Properties -:- For detailed product information, please contact sales. -:

Applications of JIS SKH58 Molybdenum High Speed Tool Steel Sheet,Plate -:- For detailed product information, please contact sales. -: Chemical Identifiers JIS SKH58 Molybdenum High Speed Tool Steel Sheet,Plate -:- For detailed product information, please contact sales. -:

Packing of JIS SKH58 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 3288 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