Bohler-Uddeholm BÖHLER W400 VMR® H11 Hot Work Tool Steel

Bohler-Uddeholm BÖHLER W400 VMR® H11 Hot Work Tool Steel Product Information -:- For detailed product information, please contact sales. -: Bohler-Uddeholm BÖHLER W400 VMR® H11 Hot Work Tool Steel Synonyms -:- For detailed product information, please contact sales. -:

Bohler-Uddeholm BÖHLER W400 VMR® H11 Hot Work Tool Steel Product Information -:- For detailed product information, please contact sales. -: # **Böhler-Uddeholm BÖHLER W400 VMR® H11 Hot Work Tool Steel** ## **Product Overview** **BÖHLER W400 VMR®** is a premium-grade **air-hardening chromium hot work tool steel** conforming to AISI H11 specifications, manufactured using Böhler-Uddeholm's proprietary **VMR® (Vacuum Melted and Remelted)** process. This advanced dual vacuum melting technology ensures exceptional **internal cleanliness, microstructural homogeneity, and superior isotropy**. W400 VMR® is specifically engineered to deliver **excellent toughness, high thermal fatigue resistance, and good machinability**, making it an ideal choice for demanding hot work applications—particularly in aluminum extrusion, forging, and die-casting—where resistance to heat checking and mechanical shock are paramount. --- ## **1. Key Characteristics & Advantages** * **Exceptional Toughness:** Offers superior impact strength and fracture resistance at both ambient and elevated temperatures compared to higher-alloy hot work steels like H13. * **Excellent Thermal Fatigue Resistance:** Highly resistant to the initiation and propagation of heat checking cracks under cyclic thermal loading. * **Superior Internal Cleanliness:** The VMR® process dramatically reduces non-metallic inclusions and gas content (oxygen, hydrogen, nitrogen), resulting in improved mechanical properties and polishability. * **Good Machinability:** In the annealed condition, exhibits better machinability than many other hot work steels, reducing manufacturing time and cost. * **High Dimensional Stability:** Air-hardening characteristic with minimal distortion during heat treatment, suitable for complex tool geometries. * **Good Resistance to Thermal Softening:** Maintains adequate hardness and strength at moderate operating temperatures (up to ~540°C / 1000°F). * **Excellent Polishability:** The clean, homogeneous VMR® microstructure allows for very good surface finishes. * **Superior Weldability:** The low impurity content and controlled chemistry make it highly suitable for repair welding. --- ## **2. Chemical Composition (Weight %)** | Element | Carbon (C) | Chromium (Cr) | Molybdenum (Mo) | Vanadium (V) | Silicon (Si) | | :--- | :---: | :---: | :---: | :---: | :---: | | **Content** | **0.33 - 0.41** | **4.75 - 5.25** | **1.25 - 1.60** | **0.40 - 0.60** | **0.80 - 1.10** | **Alloying Rationale & VMR® Advantage:** * **Carbon (0.37%):** Balanced to provide a good combination of hardness and toughness. * **Chromium (5.0%) & Molybdenum (1.4%):** Provide deep hardenability, good high-temperature strength, and resistance to softening. * **Vanadium (0.5%):** Enhances wear resistance, refines grain size, and improves toughness. * **Silicon (1.0%):** Increases oxidation resistance and strength. * **VMR® Process Significance:** The sequential **Vacuum Induction Melting (VIM)** followed by **Vacuum Arc Remelting (VAR)** ensures: * Extremely low levels of sulfur, phosphorus, and oxides. * Minimal macro- and micro-segregation. * Very low gas content, reducing the risk of hydrogen embrittlement. * A uniform, fine-grained, and isotropic microstructure that directly translates to better fatigue life and toughness. --- ## **3. Physical & Mechanical Properties** ### **Physical Properties:** * **Density:** ~7.80 g/cm³ * **Thermal Conductivity:** ~28.5 W/(m·K) at 20°C * **Modulus of Elasticity:** ~210 GPa * **Coefficient of Thermal Expansion:** ~11.8 x 10⁻⁶/K (20-500°C) ### **Heat Treatment & Mechanical Data:** * **Annealed Hardness:** ~200 HBW (max) * **Austenitizing Temperature:** 1000 - 1030°C (1830 - 1885°F) * **Quenching Medium:** Air (forced air for sections >75mm/3"). Oil quenching can be used for complex shapes. * **Tempering:** **Double tempering is essential.** Temperature range: 540 - 650°C (1005 - 1200°F). * **Typical Working Hardness:** * **44-48 HRC** (tempered at 580-620°C): For maximum toughness and thermal fatigue resistance (e.g., aluminum extrusion dies, forging dies). * **48-51 HRC** (tempered at 540-580°C): For applications requiring higher strength while maintaining good toughness. * **Impact Toughness (Charpy V):** Typically >40 J at 46 HRC, exceptionally high for a hot work steel. * **Hot Hardness:** Maintains useful hardness up to approximately 540°C. --- ## **4. Primary Applications** W400 VMR® is the premium choice for applications where **maximum toughness and thermal fatigue resistance are more critical than extreme hot hardness**. * **Hot Aluminum Extrusion:** Dies, mandrels, backers, and containers—where its exceptional toughness resists breakage under high pressure. * **Hot Forging Dies:** Hammers, press forging dies, and inserts for steel and non-ferrous metals, benefiting from its shock resistance. * **Die-Casting:** Cores, pins, and inserts for aluminum and zinc die-casting, especially for thin, complex sections prone to cracking. * **Plastic Molds:** Cavities and cores for high-temperature engineering plastics; excellent for hot runner manifolds and nozzles. * **Press Hardening (Hot Stamping):** Tools where high toughness is required to withstand mechanical loads during forming of ultra-high-strength steel. * **General Hot Work Tooling:** Where reliability and resistance to catastrophic failure are prioritized. --- ## **5. Relevant International Standards & Comparable Grades** BÖHLER W400 VMR® is the premium, vacuum-remelted variant of the standard AISI H11 grade. | Standard | Grade / Designation | Country/Region | Quality Comparison | | :--- | :--- | :--- | :--- | | **AISI / ASTM A681** | **H11** | USA | W400 VMR® is the premium quality tier with VIM+VAR refinement. | | **DIN / Werkstoff** | **1.2343 (X38CrMoV5-1)** | Germany/EU | The standard air-melted equivalent. W400 VMR® offers superior cleanliness and isotropy. | | **JIS G4404** | **SKD6** | Japan | The Japanese H11 equivalent. | | **ISO 4957** | **X38CrMoV5-1** | International | Corresponding ISO designation. | | **GB/T 1299** | **4Cr5MoSiV1** | China | Similar chemistry; W400 VMR® defines the premium import standard. | | **Uddeholm VMR®** | **ORVAR®** | Uddeholm | Another VMR® hot work steel (H13 type). W400 is the H11 variant within the VMR® family. | **Critical Specification:** The **"VMR®"** designation is essential, guaranteeing the material has undergone dual vacuum melting for maximum internal purity and performance consistency, distinguishing it from standard air-melted or even single-vacuum melted H11. --- ## **6. Processing & Fabrication Guidelines** * **Machining:** **Very good machinability** in the annealed condition. Use sharp carbide tools. The VMR® structure provides predictable tool wear and excellent surface finishes from machining. * **Heat Treatment:** 1. **Preheating:** Essential. Recommended at 600-650°C and 800-850°C. 2. **Austenitizing:** Must be performed in a **vacuum or controlled atmosphere furnace** to protect the clean surface from decarburization. 3. **Quenching:** Air cooling is standard. For complex tools, high-pressure gas or oil quenching may be used. 4. **Tempering:** **Temper immediately after quenching.** Perform a **double temper**, allowing the tool to cool to room temperature between cycles. * **Stress Relieving:** After rough machining, a stress relief at 600-650°C is highly recommended. * **Welding:** **Excellent weldability** due to low impurity content. * **Filler Metal:** Use a matching or slightly softer hot work steel filler (e.g., Böhler UDDEHOLM WELDEX H11). * **Pre-heat:** 350-450°C. * **Post-Weld:** For critical tools, a full re-austenitizing and tempering cycle is recommended to restore optimal properties in the heat-affected zone. * **Surface Treatment:** Commonly nitrided (gas, plasma) to enhance surface hardness (>1000 HV) and wear/solder resistance without significantly affecting the core toughness. * **EDM:** Suitable. A low-temperature stress relief (400-450°C) after EDM is advisable. --- ## **7. Conclusion** **BÖHLER W400 VMR®** represents the **pinnacle of H11 hot work tool steel technology**, where ultimate **toughness, reliability, and internal integrity** are non-negotiable. The investment in the VMR® process translates directly into tools that are more resistant to catastrophic failure, exhibit longer thermal fatigue life, and provide consistent, predictable performance in the most demanding high-stress, high-temperature environments. For applications like aluminum extrusion dies and heavy forging tools, where the cost of unexpected tool failure is extremely high, W400 VMR® provides an unparalleled level of security and performance. It is the definitive choice for engineers and toolmakers who prioritize **maximum toughness and fatigue resistance over extreme hot hardness**, and who understand that the highest material quality is the foundation of tooling reliability and productivity. -:- For detailed product information, please contact sales. -: Bohler-Uddeholm BÖHLER W400 VMR® H11 Hot Work Tool Steel Specification Dimensions Size： Diameter 20-1000 mm Length <6899 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 W400 VMR® H11 Hot Work Tool Steel Properties -:- For detailed product information, please contact sales. -:

Applications of Bohler-Uddeholm BÖHLER W400 VMR® H11 Hot Work Tool Steel -:- For detailed product information, please contact sales. -: Chemical Identifiers Bohler-Uddeholm BÖHLER W400 VMR® H11 Hot Work Tool Steel -:- For detailed product information, please contact sales. -:

Packing of Bohler-Uddeholm BÖHLER W400 VMR® H11 Hot 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 3370 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