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Technical Specifications
Product Overview
Metallurgical Characteristics
AISI H21 is a tungsten-type hot work tool steel characterized by its high tungsten content (8.5-10.0%) which provides exceptional high-temperature strength and thermal shock resistance. The steel's microstructure consists of a tempered martensitic matrix with uniformly distributed tungsten and vanadium carbides. These carbides maintain their hardness and wear resistance at elevated temperatures, making H21 ideal for hot work applications. The chromium content (3.0-3.75%) enhances hardenability and provides moderate corrosion resistance.
Heat Treatment Process
MetalZenith employs precision-controlled heat treatment cycles optimized for AISI H21. Annealing is performed at 870-900°C followed by slow cooling to achieve maximum machinability. Hardening involves preheating to 650-700°C, then heating to 1000-1030°C in a protective atmosphere, followed by air cooling or oil quenching depending on section size. Tempering is conducted at 540-650°C to achieve the desired working hardness of 42-48 HRC. Double tempering is recommended to ensure dimensional stability and stress relief.
Manufacturing Process Excellence
Our manufacturing process begins with vacuum induction melting (VIM) using high-purity raw materials, followed by electroslag remelting (ESR) to eliminate inclusions and achieve exceptional cleanliness. The ingots undergo controlled forging and rolling operations to refine the grain structure and ensure uniform carbide distribution. Hot working is performed within the temperature range of 1150-850°C with careful control of deformation rates to prevent cracking. All products undergo comprehensive ultrasonic testing, chemical analysis, and mechanical property verification.
Quality Standards & Certifications
MetalZenith maintains ISO 9001:2015 certification and complies with international standards including ASTM A681, EN ISO 4957, and JIS SKD61. Our quality control laboratory is equipped with advanced testing equipment including optical emission spectrometers, universal testing machines, hardness testers, and metallographic analysis systems. Each batch undergoes rigorous testing including chemical composition verification, mechanical property testing, microstructure examination, and dimensional inspection. Complete material traceability and certification documentation is provided with every shipment.
🧪 Chemical Composition
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.28 - 0.35 |
| Manganese (Mn) | 0.15 - 0.40 |
| Silicon (Si) | 0.15 - 0.40 |
| Phosphorus (P) | ≤ 0.030 |
| Sulfur (S) | ≤ 0.030 |
| Chromium (Cr) | 3.00 - 3.75 |
| Tungsten (W) | 8.50 - 10.00 |
| Vanadium (V) | 0.30 - 0.60 |
| Nickel (Ni) | ≤ 0.30 |
| Molybdenum (Mo) | ≤ 0.30 |
| Copper (Cu) | ≤ 0.25 |
⚙️ Mechanical Properties
| Property | Value | Condition |
|---|---|---|
| Tensile Strength | 1380 - 1520 MPa | Hardened & Tempered |
| Yield Strength (0.2% offset) | 1240 - 1380 MPa | Hardened & Tempered |
| Elongation | 8 - 12% | Hardened & Tempered |
| Reduction of Area | 25 - 35% | Hardened & Tempered |
| Hardness (HRC) | 42 - 48 | Working Hardness |
| Hardness (HRC) | 52 - 58 | Maximum Hardness |
| Impact Energy (Charpy V-notch) | 15 - 25 J | Room Temperature |
| Fatigue Limit | 620 - 690 MPa | 10&sup7; cycles |
| Modulus of Elasticity | 210 - 220 GPa | Room Temperature |
| Poisson's Ratio | 0.27 - 0.30 | Room Temperature |
🔬 Physical Properties
| Property | Value | Temperature |
|---|---|---|
| Density | 8.15 g/cm³ | 20°C |
| Melting Point | 1480 - 1520°C | - |
| Thermal Conductivity | 24.5 W/m·K | 20°C |
| Thermal Conductivity | 28.8 W/m·K | 400°C |
| Thermal Expansion Coefficient | 11.2×10-6/K | 20-100°C |
| Thermal Expansion Coefficient | 12.8×10-6/K | 20-400°C |
| Specific Heat Capacity | 460 J/kg·K | 20°C |
| Electrical Resistivity | 0.65 µΩ·m | 20°C |
| Magnetic Permeability | Ferromagnetic | Room Temperature |
| Thermal Diffusivity | 6.5×10-6 m²/s | 20°C |
📏 Product Specifications
| Specification | Available Options | Standards |
|---|---|---|
| Product Forms | Round bars, flat bars, plates, blocks, forgings | ASTM A681 |
| Round Bar Diameter | 10 - 500 mm | ASTM A681 |
| Flat Bar Thickness | 8 - 150 mm | ASTM A681 |
| Plate Thickness | 20 - 300 mm | ASTM A681 |
| Block Dimensions | Up to 1000×500×300 mm | Custom |
| Surface Finish | Hot rolled, annealed, turned, ground | ASTM A681 |
| Dimensional Tolerance | ±0.5 mm (standard), ±0.1 mm (precision) | ISO 2768 |
| Length | Up to 6000 mm (standard), longer available | Custom |
| Heat Treatment Condition | Annealed, normalized, hardened & tempered | ASTM A681 |
| Quality Standards | ISO 9001:2015, ASTM A681, EN ISO 4957 | International |
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Our Advantages in Processing AISI H21
Advanced Vacuum Melting Technology
MetalZenith employs vacuum induction melting (VIM) and electroslag remelting (ESR) processes to produce AISI H21 with exceptional cleanliness and homogeneity. Our controlled atmosphere melting eliminates inclusions and ensures optimal carbide distribution, resulting in superior mechanical properties and extended tool life performance.
Precision Heat Treatment Control
Our state-of-the-art heat treatment facilities feature computer-controlled furnaces with precise temperature uniformity and atmosphere control. We implement proprietary heat treatment cycles optimized for AISI H21, ensuring consistent hardness profiles, dimensional stability, and maximum thermal shock resistance across all product forms.
Complete Customization & Technical Support
MetalZenith offers comprehensive customization services including precision machining, surface treatments, and application-specific heat treatment. Our metallurgical engineering team provides technical consultation, failure analysis, and tool optimization services, supported by our global supply chain and rapid delivery capabilities.
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