AISI Type H21 Tool Steel Tube,Pipe

AISI Type H21 Tool Steel Tube Product Information -:- For detailed product information, please contact sales. -: AISI Type H21 Tool Steel Tube Synonyms -:- For detailed product information, please contact sales. -:

AISI Type H21 Tool Steel Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: AISI Type H21 Tool Steel** ## **Overview** **AISI Type H21** is a **high-tungsten, chromium-based hot work tool steel** representing the foundational grade of the tungsten series hot work steels. Characterized by its **significant tungsten content (8-10%) with balanced chromium and vanadium**, H21 is engineered to provide **exceptional hot hardness, excellent resistance to thermal softening, and good high-temperature strength**. As a quintessential tungsten hot work steel, H21 delivers reliable performance in the most demanding high-temperature applications, particularly in hot forging and extrusion operations where temperatures exceed the capabilities of chromium-molybdenum grades like H13. --- ## **Chemical Composition (Typical Weight %)** H21 features a classic tungsten-chromium-vanadium composition optimized for extreme temperature service. | Element | Content (%) | Role in Hot Work Performance | | :--- | :--- | :--- | | **Tungsten (W)** | **8.00 - 10.00** | **Primary high-temperature strengthening element.** Forms stable tungsten carbides (WC, W₂C) that provide exceptional red hardness and resist softening at extreme temperatures. | | **Chromium (Cr)** | **3.00 - 3.75** | Provides oxidation resistance, moderate hardenability, and contributes to hot strength through chromium carbide formation. | | **Vanadium (V)** | **0.30 - 0.60** | Forms vanadium carbides that refine grain size, improve elevated-temperature properties, and enhance wear resistance. | | **Carbon (C)** | **0.25 - 0.35** | Lower carbon content than many hot work steels to maintain toughness at high temperatures while providing adequate hardness. | | **Silicon (Si)** | 0.15 - 0.40 | Increases resistance to oxidation. | | **Manganese (Mn)** | 0.20 - 0.50 | Aids hardenability and deoxidization. | | **Molybdenum (Mo)** | **≤ 0.30** | Minimal content; H21 relies on tungsten rather than molybdenum for high-temperature properties. | | **Sulfur (S)** | ≤ 0.03 | - | | **Phosphorus (P)** | ≤ 0.03 | - | | **Iron (Fe)** | **Balance** | Base metal. | **Key Distinction:** H21's **high tungsten content with relatively low carbon** distinguishes it from both chromium-molybdenum hot work steels and higher-carbon tungsten grades. This combination prioritizes hot hardness and toughness over maximum room-temperature hardness. --- ## **Physical & Mechanical Properties** *Properties are for material in the hardened and tempered condition.* | Property | Typical Value / Description | | :--- | :--- | | **Density** | ~8.25 g/cm³ (Higher than molybdenum-based grades due to tungsten) | | **Hardness (Annealed)** | 200 - 230 HB | | **Hardness (Hardened & Tempered)** | **42 - 52 HRC** (Typically operated at 46-50 HRC for hot work) | | **Hot Hardness (at 650°C / 1200°F)** | **~40-44 HRC** (Exceptional retention of hardness at extreme temperatures) | | **Tensile Strength** | 1400 - 1700 MPa (at 48 HRC) | | **Yield Strength (0.2%)** | 1200 - 1500 MPa (at 48 HRC) | | **Elongation** | 6 - 12% (at 48 HRC) | | **Impact Toughness (Charpy)** | **15 - 25 J** (at 48 HRC; relatively good for a tungsten hot work steel) | | **Thermal Fatigue Resistance** | **Fair.** Adequate for many applications but generally inferior to H13 in severe thermal cycling due to lower thermal conductivity. | | **Thermal Conductivity** | **~24.0 W/m·K** at 20°C (Lower than molybdenum-based grades) | | **Coefficient of Thermal Expansion** | ~11.7 × 10⁻⁶/°C (20-500°C) | | **Maximum Continuous Service Temperature** | **~650°C (1200°F)** | | **Specific Heat Capacity** | 460 J/kg·K | | **Machinability (Annealed)** | **Fair** (~50% of 1% carbon steel). | | **Grindability** | **Fair to Poor.** | --- ## **Heat Treatment Guidelines** Proper heat treatment is critical to develop H21's optimal high-temperature properties. | Process | Parameters | Special Considerations for H21 | | :--- | :--- | :--- | | **Annealing** | Heat to 850-880°C (1560-1615°F), slow furnace cool to 480°C (900°F) at ≤15°C/hr, then air cool. | Results in ~215 HB for machining. | | **Stress Relieving** | 650-700°C (1200-1290°F) for 2 hrs, air cool. | Recommended after rough machining. | | **Preheating** | **Double preheat:** 650°C (1200°F) and 850°C (1560°F). | Critical to prevent thermal shock during high-temperature austenitizing. | | **Austenitizing** | **1100-1150°C (2010-2100°F).** Soak: 20-30 min/inch. | **High temperature required** to dissolve tungsten carbides; must use protective atmosphere or salt bath. | | **Quenching** | **Oil quench** (standard) or air quench for complex shapes. | Oil quenching (40-60°C oil) ensures maximum hardness; air quenching minimizes distortion. | | **Tempering** | **Double temper at 600-650°C (1110-1200°F)** for 2+ hours each. | **Must temper immediately** after quenching; high temperatures develop optimal secondary hardening. | --- ## **Product Applications** H21 is specialized for high-temperature applications where exceptional hot hardness is required. ### **Primary Hot Work Applications:** #### **1. Hot Forging (Primary Application):** - **Hammer and press forging dies** for steel, alloy steel, and high-temperature alloys - **Forging dies for brass and copper alloys** - **Die inserts for high-temperature forging** #### **2. Hot Extrusion:** - **Extrusion dies and mandrels** for copper, brass, and bronze - **Dummy blocks and containers** for high-temperature extrusion #### **3. Other High-Temperature Applications:** - **Hot piercing punches and mandrels** - **Hot shear blades** for cutting hot metals - **Tools for powder metallurgy hot pressing** - **Glass forming tools** (molds, plungers) ### **Specific Industry Usage:** - **Forging Industry** (automotive, aerospace components) - **Non-Ferrous Metal Extrusion** (copper, brass manufacturers) - **Heavy Equipment Manufacturing** - **Glass Production** - **High-Temperature Tooling for Special Alloys** --- ## **International Standards & Cross-Reference** H21 is widely recognized with direct equivalents in major international systems. | Standard | Designation | Equivalent / Similar Grade | | :--- | :--- | :--- | | **AISI/SAE (USA)** | **H21** | - | | **UNS (USA)** | **T20821** | - | | **ASTM (USA)** | A681 | Grade H21 | | **Europe (EN)** | **1.2581** | X30WCrV9-3 | | **Germany (DIN)** | **1.2581** | X30WCrV9-3 | | **Japan (JIS)** | **SKD5** | - | | **ISO** | **HS30-9-3** | - | | **UK (BS)** | **BH21** | - | | **China (GB)** | **3Cr2W8V** | - | | **Sweden (SS)** | **2732** | - | --- ## **Technical Comparison: H21 vs. Other Hot Work Steels** | Property | **H21 (UNS T20821)** | **H13 (UNS T20813)** | **H10 (UNS T20810)** | | :--- | :--- | :--- | :--- | | **Primary Alloy System** | **Tungsten-based** | Chromium-Molybdenum | Chromium-Molybdenum | | **Tungsten Content** | **8.00-10.00%** | 0% | 0% | | **Hot Hardness (at 600°C)** | **~42-44 HRC** | ~34-36 HRC | ~36-38 HRC | | **Maximum Service Temp** | **~650°C (1200°F)** | ~540°C (1000°F) | ~540°C (1000°F) | | **Toughness (at 48 HRC)** | 15-25 J | **25-40 J** | 20-35 J | | **Thermal Conductivity** | ~24.0 W/m·K | **~28.0 W/m·K** | ~28.5 W/m·K | | **Thermal Fatigue Resistance** | Fair | **Excellent** | Very Good | | **Primary Application** | **High-temp forging** | **Die casting** | **Thermal fatigue apps** | | **Relative Cost** | High | Moderate | Moderate | --- ## **Advantages & Considerations** ### **Advantages:** 1. **Exceptional Hot Hardness:** Maintains hardness at temperatures up to 650°C, superior to chromium-molybdenum grades. 2. **Good High-Temperature Strength:** Excellent resistance to deformation under high-temperature stress. 3. **Resistance to Thermal Softening:** Tungsten carbides provide outstanding resistance to tempering effects. 4. **Good Toughness for a Tungsten Steel:** Relatively good impact resistance compared to other tungsten hot work steels. 5. **Good Wear Resistance at Temperature:** Suitable for high-temperature abrasive applications. ### **Considerations:** 1. **Lower Thermal Conductivity:** Reduced heat dissipation compared to molybdenum-based grades, potentially leading to thermal gradients. 2. **Reduced Thermal Fatigue Resistance:** More susceptible to heat checking than H13 in severe thermal cycling applications. 3. **Complex Heat Treatment:** Requires precise control of high-temperature processing. 4. **Higher Cost:** Tungsten is an expensive alloying element. 5. **Lower Oxidation Resistance:** Reduced chromium content compared to H13 lowers oxidation resistance. 6. **Specific Application Focus:** Over-specified for applications below 500°C; best for high-temperature use. --- ## **Metallurgical Characteristics** ### **Tungsten Strengthening Mechanisms:** 1. **Carbide Formation:** Primary strengthening through stable tungsten carbides (WC, W₂C). 2. **Solid Solution Strengthening:** Tungsten in solid solution enhances high-temperature strength. 3. **Grain Refinement:** Inhibits austenite grain growth during high-temperature processing. ### **Microstructural Stability:** H21's tungsten carbides provide excellent microstructural stability at high temperatures: - **Resistance to Carbide Coarsening:** Tungsten carbides resist growth during prolonged high-temperature exposure. - **Tempering Resistance:** Maintains hardness better than molybdenum-based steels during high-temperature service. - **Creep Resistance:** Good resistance to deformation under sustained high-temperature stress. --- ## **Special Processing & Fabrication** ### **Forging Recommendations:** - **Start Forging:** 1150-1200°C (2100-2190°F) - **Finish Forging:** ≥950°C (1740°F) - **Cooling After Forging:** Slow furnace cool or bury in insulating material ### **Machining (Annealed State):** - Use carbide tools with positive rake angles - Moderate cutting speeds with adequate feed rates - Use coolant to manage heat and extend tool life - Stress relieve after heavy machining ### **Grinding (Hardened State):** - Aluminum oxide or CBN wheels recommended - Light infeeds with consistent traverse rates - Ample coolant to prevent thermal damage --- ## **Surface Treatments & Enhancements** ### **Recommended Surface Treatments:** 1. **Nitriding:** Improves surface hardness (1000-1200 HV), wear resistance, and corrosion resistance. 2. **PVD Coatings:** TiN, TiAlN, or CrN coatings can enhance performance in specific applications. 3. **Oxidation Treatments:** Can improve high-temperature oxidation resistance. ### **Benefits of Surface Treatment:** - Extended tool life in abrasive applications - Improved resistance to soldering and galling - Enhanced performance in specific operating conditions --- ## **Economic & Selection Considerations** ### **When to Select H21:** 1. Operating temperatures consistently exceed 550°C 2. Hot hardness is the primary failure mode (thermal softening) 3. Application involves high-temperature forging or extrusion 4. H13 or similar grades show premature softening 5. The increased cost is justified by extended tool life ### **Cost-Benefit Analysis:** While H21 has higher initial costs (material and processing), its extended tool life in appropriate high-temperature applications can result in: - Lower cost per part produced - Reduced downtime for tool changes - Improved process consistency and quality --- ## **Modern Alternatives & Evolution** While H21 remains a viable and widely used grade, modern developments include: 1. **Premium ESR/VAR H21:** Improved cleanliness and isotropic properties 2. **Modified Tungsten Grades:** With cobalt or other additions for enhanced properties 3. **Powder Metallurgy Alternatives:** For improved toughness and performance 4. **Nickel-based Superalloys:** For extreme temperature applications (>700°C) --- ## **Conclusion** **AISI Type H21 Tool Steel** stands as the **classic and most widely used tungsten-based hot work steel**, offering **exceptional hot hardness and high-temperature performance** for demanding forging, extrusion, and other high-temperature applications. Its **balanced tungsten-chromium-vanadium composition** provides an optimal combination of **hot hardness, toughness, and workability** that has made it a mainstay in high-temperature tooling for decades. While its **lower thermal conductivity and reduced thermal fatigue resistance** compared to chromium-molybdenum grades like H13 limit its use in severe thermal cycling applications, H21 remains **unmatched for pure hot hardness applications** in the 550-650°C range. For tooling engineers working with **high-temperature forging, brass/copper extrusion, or other applications** where thermal softening is the primary failure mode, H21 provides a **proven, reliable solution** with a long history of successful performance. As manufacturing processes continue to evolve and demand higher performance from tooling materials, H21 maintains its relevance as a **specialized, high-performance option** for specific high-temperature applications, demonstrating the enduring value of well-designed tungsten-based alloy systems in hot work tooling. -:- For detailed product information, please contact sales. -: AISI Type H21 Tool Steel Specification Dimensions Size： Diameter 20-1000 mm Length <6694 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. -: AISI Type H21 Tool Steel Properties -:- For detailed product information, please contact sales. -:

Applications of AISI Type H21 Tool Steel Tube -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI Type H21 Tool Steel Tube -:- For detailed product information, please contact sales. -:

Packing of AISI Type H21 Tool Steel Tube -:- 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 Tube 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 3165 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