AISI Type H26 Tungsten Hot Work Tool Steel Tube,Pipe (UNS T20826)

AISI Type H26 Tungsten Hot Work Tool Steel Tube (UNS T20826) Product Information -:- For detailed product information, please contact sales. -: AISI Type H26 Tungsten Hot Work Tool Steel Tube (UNS T20826) Synonyms -:- For detailed product information, please contact sales. -:

AISI Type H26 Tungsten Hot Work Tool Steel (UNS T20826) Product Information -:- For detailed product information, please contact sales. -: # **Product Introduction: AISI Type H26 Tungsten Hot Work Tool Steel (UNS T20826)** ## **Overview** **AISI Type H26 (UNS T20826)** is a **very high-tungsten, chromium-based hot work tool steel** representing one of the final members of the traditional tungsten series hot work steels. Characterized by its **substantial tungsten content with balanced chromium and vanadium additions**, H26 is engineered to provide **exceptional hot hardness and high-temperature stability** for demanding thermal applications. This grade bridges the gap between conventional tungsten hot work steels and more specialized compositions, offering a balanced approach to extreme temperature service with particular emphasis on wear resistance at elevated temperatures. --- ## **Chemical Composition (Typical Weight %)** H26 features a high-tungsten composition with carefully balanced supporting elements. | Element | Content (%) | Role in Hot Work Performance | | :--- | :--- | :--- | | **Tungsten (W)** | **17.00 - 19.00** | **Exceptionally high tungsten content.** Forms a dense, stable network of tungsten carbides (WC, W₂C) providing maximum red hardness and resistance to thermal softening. | | **Chromium (Cr)** | **3.75 - 4.50** | Provides essential oxidation resistance, contributes to hardenability, and forms chromium carbides that complement the tungsten carbide network. | | **Vanadium (V)** | **0.75 - 1.25** | **Significant vanadium content.** Forms ultra-hard vanadium carbides (VC) for enhanced wear resistance at high temperatures and refines grain structure. | | **Carbon (C)** | **0.45 - 0.55** | **Higher carbon than other tungsten H-grades.** Provides increased carbide volume for better wear resistance while maintaining adequate toughness. | | **Molybdenum (Mo)** | **≤ 0.50** | Minimal; H26 relies primarily on tungsten for high-temperature properties. | | **Silicon (Si)** | 0.15 - 0.40 | Improves oxidation resistance. | | **Manganese (Mn)** | 0.20 - 0.50 | Aids hardenability and deoxidization. | | **Sulfur (S)** | ≤ 0.03 | - | | **Phosphorus (P)** | ≤ 0.03 | - | | **Cobalt (Co)** | **0%** | Notably absent; distinguishes H26 from cobalt-containing grades like H24/H25. | | **Iron (Fe)** | **Balance** | Base metal. | **Key Distinction:** H26's **very high tungsten content (17-19%) with zero cobalt** distinguishes it from the cobalt-enhanced tungsten grades (H24, H25). This creates a material that relies exclusively on carbide strengthening (tungsten and vanadium carbides) rather than combined carbide and matrix (cobalt) strengthening. The **higher carbon content (0.45-0.55%)** compared to other tungsten H-grades also provides greater carbide volume for enhanced wear resistance. --- ## **Physical & Mechanical Properties** *Properties are for material in the hardened and tempered condition.* | Property | Typical Value / Description | | :--- | :--- | | **Density** | ~8.80 g/cm³ (Very high due to extreme tungsten content) | | **Hardness (Annealed)** | 235 - 265 HB | | **Hardness (Hardened & Tempered)** | **46 - 56 HRC** (Typically operated at 50-54 HRC for hot work) | | **Hot Hardness (at 650°C / 1200°F)** | **~44-48 HRC** (Exceptional retention at high temperatures) | | **Tensile Strength** | 1650 - 2000 MPa (at 52 HRC) | | **Yield Strength (0.2%)** | 1450 - 1800 MPa (at 52 HRC) | | **Elongation** | **3 - 7%** (at 52 HRC; low due to high carbide volume) | | **Impact Toughness (Charpy)** | **6 - 12 J** (at 52 HRC; very low - characteristic limitation) | | **Thermal Fatigue Resistance** | **Fair to Good.** Adequate for many applications but challenged by low thermal conductivity. | | **Thermal Conductivity** | **~21.5 W/m·K** at 20°C (Very low due to extreme alloy content) | | **Coefficient of Thermal Expansion** | ~11.2 × 10⁻⁶/°C (20-500°C) | | **Maximum Continuous Service Temperature** | **~680°C (1255°F)** | | **Specific Heat Capacity** | 460 J/kg·K | | **Machinability (Annealed)** | **Extremely Poor** (~20-25% of 1% carbon steel). Exceptionally difficult. | | **Grindability** | **Extremely Poor.** Among the most challenging steels to grind. | --- ## **Heat Treatment Guidelines** H26 requires extreme care in heat treatment due to its high alloy content and sensitivity. | Process | Parameters | Critical Considerations for H26 | | :--- | :--- | :--- | | **Annealing** | Heat to 870-900°C (1600-1650°F), slow furnace cool to 480°C (900°F) at ≤8°C/hr, then air cool. | Results in ~250 HB; essential for any machining attempts. | | **Stress Relieving** | 650-700°C (1200-1290°F) for 3-4 hrs, slow furnace cool. | Mandatory after machining to prevent stress-induced cracking. | | **Preheating** | **Triple preheat:** 400°C (750°F), 650°C (1200°F), and 850°C (1560°F). | Critical to prevent thermal shock during high-temperature austenitizing. | | **Austenitizing** | **1220-1260°C (2230-2300°F).** Soak: 20-40 min/inch. | **Extreme temperature required** to dissolve tungsten carbides; vacuum atmosphere essential. | | **Quenching** | **Oil quench** with vigorous agitation or **high-pressure gas quench.** | Rapid cooling necessary; air quenching generally insufficient for full hardness. | | **Tempering** | **Triple temper at 630-680°C (1165-1255°F)** for 2+ hours each. Cryogenic treatment between tempers recommended. | High tempering temperatures required; must begin tempering immediately after quenching. | --- ## **Product Applications** H26 is specialized for extreme high-temperature applications requiring maximum hot hardness without cobalt. ### **Primary Hot Work Applications:** #### **1. High-Temperature Forging:** - **Dies for high-alloy steel forging** at 600-750°C - **Hot die forging tools** for nickel-based alloys - **Forging dies for specialized high-temperature materials** #### **2. Hot Extrusion Tooling:** - **Extrusion dies for copper and copper alloys** - **Mandrels for high-temperature extrusion** - **Tools for specialized metal extrusion processes** #### **3. Wear-Intensive High-Temperature Applications:** - **Hot work tools subject to severe abrasion** at elevated temperatures - **Die casting tools for abrasive high-temperature alloys** - **Tools for hot powder compaction** of hard materials ### **Specific Industry Usage:** - **Specialty Metal Forging** (high-alloy steels, certain superalloys) - **Non-Ferrous Metal Processing** (copper, brass industries) - **Advanced Materials Manufacturing** - **Research & Development** in high-temperature tooling --- ## **International Standards & Cross-Reference** H26 is a highly specialized grade with limited international recognition. | Standard | Designation | Equivalent / Similar Grade | | :--- | :--- | :--- | | **AISI/SAE (USA)** | **H26** | - | | **UNS (USA)** | **T20826** | - | | **ASTM (USA)** | A681 | Grade H26 | | **Europe (EN)** | **No equivalent** | - | | **Germany (DIN)** | **No equivalent** | - | | **Japan (JIS)** | **No equivalent** | - | | **ISO** | **No equivalent** | - | | **UK (BS)** | **No equivalent** | - | **Critical Note:** **AISI H26 has no direct international equivalents.** Its extreme tungsten content without cobalt creates a unique composition that falls outside standard international tool steel classifications. It is essentially exclusive to the AISI/SAE system and is rarely specified even within that framework. --- ## **Technical Comparison: H26 vs. Other Tungsten Hot Work Steels** | Property | **H26 (UNS T20826)** | **H21 (UNS T20821)** | **H23 (UNS T20823)** | | :--- | :--- | :--- | :--- | | **Tungsten Content** | **17.00-19.00%** | 8.00-10.00% | 11.00-12.75% | | **Cobalt Content** | **0%** | 0% | 0% | | **Chromium Content** | 3.75-4.50% | 3.00-3.75% | **11.00-12.75%** | | **Carbon Content** | **0.45-0.55%** | 0.25-0.35% | 0.25-0.35% | | **Hot Hardness (at 650°C)** | **~44-48 HRC** | ~40-44 HRC | ~42-46 HRC | | **Wear Resistance** | **Best** (high carbon + vanadium) | Good | Very Good | | **Toughness (at 52 HRC)** | 6-12 J | **15-25 J** | 8-15 J | | **Maximum Service Temp** | **~680°C (1255°F)** | ~650°C (1200°F) | ~700°C (1290°F) | | **Primary Characteristic** | **Max Wear at High Temp** | Balanced Performance | **High Temp + Oxidation** | --- ## **Advantages & Considerations** ### **Advantages:** 1. **Exceptional Hot Hardness:** Outstanding resistance to softening at high temperatures due to extreme tungsten content. 2. **Superior High-Temperature Wear Resistance:** High carbon and vanadium content provides excellent abrasion resistance at elevated temperatures. 3. **Cobalt-Free Composition:** Advantageous when cobalt is undesirable due to cost, supply, or specific application requirements. 4. **Good High-Temperature Stability:** Maintains properties well during prolonged high-temperature exposure. ### **Considerations & Limitations:** 1. **Extremely Low Toughness:** Very brittle at all temperatures; requires meticulous handling and design. 2. **Very High Cost:** Extreme tungsten content makes it very expensive. 3. **Extremely Complex Heat Treatment:** Demands specialized equipment and expertise. 4. **Very Poor Thermal Conductivity:** Severe thermal gradients and stress concentrations. 5. **Near-Impossible Machinability:** Fabrication is exceptionally difficult and costly. 6. **Very Limited Availability:** Essentially special-order only with long lead times. 7. **Niche Application:** Only justifiable for specific extreme applications. --- ## **Special Metallurgical Characteristics** ### **Tungsten-Dominant Microstructure:** 1. **High Carbide Volume:** Extreme tungsten content creates very high volume fraction of tungsten carbides. 2. **Carbon Optimization:** Higher carbon than other tungsten H-grades increases carbide formation while maintaining some matrix integrity. 3. **Vanadium Enhancement:** Significant vanadium content provides additional wear resistance through VC carbides. ### **Absence of Cobalt Effects:** - **Pure Carbide Strengthening:** Relies exclusively on carbide strengthening rather than combined carbide-matrix strengthening. - **Different Tempering Response:** Exhibits different secondary hardening behavior compared to cobalt-containing grades. - **Matrix Characteristics:** Ferrite matrix has different high-temperature behavior without cobalt solid solution strengthening. --- ## **Processing Challenges** ### **Fabrication Considerations:** 1. **Consider Near-Net-Shape Forming:** Where possible, to minimize machining 2. **EDM Preferred:** For complex shapes, despite slow processing 3. **Specialized Grinding:** Required for final dimensions and surface finish 4. **Minimal Post-Heat-Treatment Machining:** Due to extreme hardness ### **Heat Treatment Criticalities:** 1. **Atmosphere Control:** Essential to prevent catastrophic decarburization 2. **Temperature Uniformity:** ±5°C control necessary during austenitizing 3. **Quenching Rate:** Must be rapid enough to achieve full hardness 4. **Tempering Precision:** Critical to develop optimal properties without overtempering --- ## **Economic & Practical Considerations** ### **Application Justification:** H26 might be considered when: 1. Maximum hot hardness is required without cobalt 2. High-temperature wear resistance is paramount 3. Alternative materials have failed 4. Budget allows for extreme material and processing costs 5. Application can accommodate very low toughness ### **Cost Analysis:** - **Material Cost:** 4-8× higher than H13 - **Fabrication Cost:** 3-6× higher due to machining difficulty - **Heat Treatment Cost:** 2-4× higher with specialized equipment - **Total Investment:** Often prohibitive for commercial applications --- ## **Modern Context & Alternatives** ### **Contemporary Alternatives:** 1. **Advanced Coatings:** PVD/CVD coatings on more economical substrates 2. **Powder Metallurgy Tool Steels:** For better toughness at high hardness 3. **Ceramic and Cermet Tooling:** For specific extreme conditions 4. **Modified Standard Grades:** Enhanced versions of H13, H21 with better balance of properties ### **H26's Diminishing Role:** In modern manufacturing, H26's applications have largely been superseded by: - **More manufacturable materials** with adequate performance - **Advanced surface engineering** techniques - **Improved process controls** that reduce tooling demands - **Alternative manufacturing approaches** that avoid extreme conditions --- ## **Conclusion** **AISI Type H26 Tungsten Hot Work Tool Steel (UNS T20826)** represents the **final evolution of traditional high-tungsten, non-cobalt hot work steels**, offering **extreme hot hardness and high-temperature wear resistance** through its remarkable tungsten content (17-19%) and optimized carbon level. As a material that **pushes traditional alloying to its practical limits**, H26 demonstrates both the **potential and the challenges** of extreme tungsten-based compositions. However, its **severe limitations in toughness, manufacturability, and cost** have rendered it largely obsolete for most practical applications. In today's manufacturing landscape, H26 serves more as a **metallurgical curiosity and historical benchmark** than as a viable production material for all but the most specialized, well-funded applications. The story of H26 illustrates an important principle in materials engineering: that **extreme performance in one area often comes at unacceptable costs in others**. While it remains a fascinating example of traditional metallurgical extremes, H26's practical relevance has been largely supplanted by more balanced, manufacturable alternatives and advanced surface engineering technologies. For materials historians and specialists, H26 represents an important chapter in the development of high-temperature tool steels. For practical engineers and manufacturers, it serves as a reminder to seek balanced solutions rather than pursuing single-property extremes at all costs. -:- For detailed product information, please contact sales. -: AISI Type H26 Tungsten Hot Work Tool Steel (UNS T20826) Specification Dimensions Size： Diameter 20-1000 mm Length <6699 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 H26 Tungsten Hot Work Tool Steel (UNS T20826) Properties -:- For detailed product information, please contact sales. -:

Applications of AISI Type H26 Tungsten Hot Work Tool Steel Tube (UNS T20826) -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI Type H26 Tungsten Hot Work Tool Steel Tube (UNS T20826) -:- For detailed product information, please contact sales. -:

Packing of AISI Type H26 Tungsten Hot Work Tool Steel Tube (UNS T20826) -:- 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 3170 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