Bohler-Uddeholm BÖHLER S500(m42) High Speed Steel

Bohler-Uddeholm BÖHLER S500(m42) High Speed Steel Product Information -:- For detailed product information, please contact sales. -: Bohler-Uddeholm BÖHLER S500(m42) High Speed Steel Synonyms -:- For detailed product information, please contact sales. -:

Bohler-Uddeholm BÖHLER S500(m42) High Speed Steel Product Information -:- For detailed product information, please contact sales. -: # **Böhler-Uddeholm BÖHLER S500 (M42) High Speed Steel** ## **Product Overview** **BÖHLER S500** is a premium **cobalt-bearing, molybdenum high-speed steel** conforming to the AISI M42 specification. As one of the most widely used super high-speed steels, S500 is engineered to deliver **exceptional red hardness (hot hardness) and superior wear resistance**. The addition of approximately 8% cobalt dramatically enhances its ability to retain hardness and cutting edge integrity at elevated temperatures, making it the material of choice for machining difficult-to-cut materials, high-speed dry machining operations, and applications where conventional high-speed steels fail due to thermal softening. --- ## **1. Key Characteristics & Advantages** * **Exceptional Red Hardness (Hot Hardness):** Outstanding ability to maintain hardness at temperatures up to 600°C (1110°F) and above, significantly outperforming non-cobalt grades like M2 and M7. * **High Wear Resistance:** Excellent resistance to abrasive wear due to a high volume of hard vanadium and molybdenum carbides. * **Good Edge Strength:** Maintains cutting edge stability under high mechanical loads and during interrupted cuts. * **Superior High-Speed Machining Performance:** Enables higher cutting speeds and feed rates than standard high-speed steels, especially when machining hardened steels, superalloys, and high-temperature alloys. * **Good Grindability (for a cobalt HSS):** While more challenging to grind than M2, it offers better grindability than many other high-cobalt or high-vanadium super HSS grades (e.g., M4, T15), facilitating tool fabrication. * **Excellent Response to Coatings:** Serves as an ideal substrate for advanced PVD coatings (TiAlN, AlCrN), creating a synergistic effect for extreme performance. --- ## **2. Typical Chemical Composition (Weight %)** | Element | Carbon (C) | Molybdenum (Mo) | Tungsten (W) | Chromium (Cr) | Vanadium (V) | Cobalt (Co) | | :--- | :---: | :---: | :---: | :---: | :---: | :---: | | **Content** | **1.05 - 1.15** | **9.00 - 10.00** | **1.15 - 1.85** | **3.50 - 4.25** | **0.95 - 1.35** | **7.75 - 8.75** | **Alloying Rationale:** * **Cobalt (8.25%):** The defining element. Cobalt does not form carbides but increases the transformation temperature, enhances hot hardness, and improves tempering resistance by slowing the coalescence of other carbides. * **High Molybdenum (9.5%):** The primary carbide former, providing the base for secondary hardening and contributing significantly to wear resistance and hot strength. * **Vanadium (1.15%):** Forms hard vanadium carbides (VC) for wear resistance. The amount is balanced to provide good wear characteristics without making the steel excessively difficult to grind. * **Carbon (~1.10%):** Balanced with the strong carbide formers (Mo, V) to achieve high hardness without excessive retained austenite. * **Tungsten (1.5%):** Works synergistically with molybdenum to enhance hot hardness. * **Chromium (3.9%):** Provides hardenability and contributes to general wear resistance. --- ## **3. Physical & Mechanical Properties** ### **Physical Properties:** * **Density:** ~8.10 g/cm³ * **Thermal Conductivity:** ~25 W/(m·K) at 20°C * **Modulus of Elasticity:** ~220 GPa * **Coefficient of Thermal Expansion:** ~11.0 x 10⁻⁶/K (20-400°C) ### **Heat Treatment & Mechanical Data:** * **Annealed Hardness:** ~260 HBW * **Austenitizing Temperature:** 1170 - 1210°C (2140 - 2210°F) * **Quenching Medium:** Salt bath, vacuum/pressurized gas, or oil. * **Tempering:** **Triple tempering is strongly recommended.** Temperature range: 540 - 590°C (1005 - 1095°F). * **Achievable Hardness:** **66 - 69 HRC** * Typical operating hardness is **67-68 HRC** after triple tempering at 550-570°C. * **Hot Hardness (600°C):** **~60-62 HRC** (This is its key advantage, approximately 5-7 HRC points higher than M2 at this temperature). * **Transverse Rupture Strength:** ~2800 - 3100 MPa * **Impact Toughness:** Moderate; lower than tough grades like M1 or M7 due to high hardness and cobalt content, but sufficient for most cutting applications. --- ## **4. Primary Applications** BÖHLER S500 (M42) is the industry standard for demanding high-speed and high-temperature machining operations. * **High-Performance Cutting Tools:** * **End mills, drills, and reamers** for machining hardened steels (45-65 HRC), stainless steels, and high-temperature alloys (Inconel, Waspaloy, titanium). * **Gear hobs and shaper cutters** for hard finishing of gears. * **Broaches** for difficult-to-machine materials. * **Thread milling cutters** and form tools. * **High-Speed/Dry Machining:** Tools designed to operate at very high surface speeds or without coolant, where frictional heat generation is extreme. * **Severe Cold Work Applications:** * **Punches and dies** for cold forming of high-strength materials. * **Precision blanking dies** for abrasive sheet materials. --- ## **5. Relevant International Standards & Comparable Grades** BÖHLER S500 is the Böhler-Uddeholm designation for AISI M42 super high-speed steel. | Standard | Grade / Designation | Country/Region | Note | | :--- | :--- | :--- | :--- | | **AISI / ASTM A600** | **M42** | USA | Direct equivalent. | | **ISO 4957** | **HS2-9-8** | International | Corresponding ISO designation (approx. 2%W, 9%Mo, 8%Co). | | **DIN / Werkstoff** | **1.3247** | Germany/EU | Common European designation for cobalt HSS. | | **JIS G4403** | **SKH59 (Co8)** | Japan | The Japanese cobalt HSS equivalent (Note: SKH59 can also refer to M7; cobalt content specifies M42). | | **Performance Comparison** | **vs. M2/M7** | N/A | Superior hot hardness and wear resistance, enabling higher cutting speeds and longer tool life in tough materials. | | **Performance Comparison** | **vs. T15 (A11)** | N/A | T15 has higher vanadium for better wear resistance but is much more difficult to grind. M42 offers a better balance of hot hardness and grindability. | --- ## **6. Processing & Fabrication Guidelines** * **Supply Form:** Round bars, square bars, flat stock, and precision ground tool blanks. * **Machining:** Machine in the soft-annealed condition. Use sharp carbide tools. The material is abrasive and work-hardens; use stable setups and appropriate parameters. * **Grinding:** **Grindability is fair for a super HSS.** More difficult than M2 but easier than high-vanadium grades like M4 or T15. Use aluminum oxide or CBN wheels with ample coolant to avoid thermal damage (grinding burns). Proper wheel selection and dressing are critical. * **EDM:** Suitable. A stress-relieving temper (~550°C) after EDM is essential to mitigate the brittle white layer. * **Heat Treatment:** Requires precise, controlled atmosphere or vacuum heat treatment. 1. **Preheating:** 800-850°C and 1050-1100°C is mandatory to prevent cracking. 2. **Austenitizing:** Temperature control is critical; too high can lead to grain growth, too low results in low hardness. 3. **Quenching:** Oil or high-pressure gas quenching is standard. 4. **Tempering:** **Triple tempering is standard practice.** Immediate tempering after quenching is required. Cryogenic treatment (-196°C) between the first and second temper can maximize hardness and dimensional stability. * **Surface Treatment:** An **excellent substrate for PVD coatings**. The combination of a hard, thermally stable S500 substrate with a lubricious, insulating coating like TiAlN or AlCrN is the standard for modern high-performance cutting tools. --- ## **7. Conclusion** **BÖHLER S500 (M42)** is the **benchmark cobalt-bearing super high-speed steel**, defining performance for machining operations that push the boundaries of speed, temperature, and material difficulty. Its unparalleled hot hardness makes it indispensable for modern aggressive machining strategies and for cutting materials that rapidly degrade conventional tool steels. While it represents a higher initial investment and requires more careful grinding and heat treatment, the return in terms of productivity gains, extended tool life, and the ability to tackle challenging materials is substantial. For tool manufacturers and machinists working with hardened steels, superalloys, or in high-speed/dry machining environments, S500 is not just an option but often the necessary foundation for success, providing the thermal stability that enables next-level machining performance. -:- For detailed product information, please contact sales. -: Bohler-Uddeholm BÖHLER S500(m42) High Speed Steel Specification Dimensions Size： Diameter 20-1000 mm Length <6904 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. -: Bohler-Uddeholm BÖHLER S500(m42) High Speed Steel Properties -:- For detailed product information, please contact sales. -:

Applications of Bohler-Uddeholm BÖHLER S500(m42) High Speed Steel -:- For detailed product information, please contact sales. -: Chemical Identifiers Bohler-Uddeholm BÖHLER S500(m42) High Speed Steel -:- For detailed product information, please contact sales. -:

Packing of Bohler-Uddeholm BÖHLER S500(m42) High Speed 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 3375 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