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Technical Specifications
Product Overview
Metallurgical Characteristics
AISI 4340 is a low-alloy steel with excellent hardenability due to its nickel, chromium, and molybdenum content. The steel exhibits a martensitic microstructure when quenched, which can be tempered to achieve the desired balance of strength and toughness. The alloy's deep hardening capability makes it suitable for large cross-sections while maintaining uniform properties throughout.
Heat Treatment Process
MetalZenith's heat treatment process begins with normalizing at 870-900°C, followed by annealing at 810-840°C for stress relief. Hardening is performed by austenitizing at 845-870°C, followed by oil quenching to achieve maximum hardness. Tempering at 200-650°C allows precise control of final mechanical properties. Our computer-controlled furnaces ensure uniform heating and cooling rates for consistent results.
Manufacturing Process
Our AISI 4340 steel production utilizes electric arc furnace melting with ladle refining and vacuum degassing to achieve superior cleanliness. The steel is cast into ingots or continuously cast billets, then hot rolled to the required dimensions. Secondary operations include precision machining, heat treatment, and surface finishing according to customer specifications. Advanced ultrasonic testing ensures internal soundness.
Quality Standards & Testing
MetalZenith maintains strict quality control throughout production, with comprehensive testing including chemical analysis by optical emission spectroscopy, mechanical testing per ASTM standards, ultrasonic inspection for internal defects, and metallographic examination. Our quality management system complies with ISO 9001:2015, AS9100D, and NADCAP requirements, ensuring consistent quality and traceability for critical applications.
🧪 Chemical Composition
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.38 - 0.43 |
| Manganese (Mn) | 0.60 - 0.80 |
| Silicon (Si) | 0.15 - 0.35 |
| Phosphorus (P) | ≤ 0.035 |
| Sulfur (S) | ≤ 0.040 |
| Chromium (Cr) | 0.70 - 0.90 |
| Nickel (Ni) | 1.65 - 2.00 |
| Molybdenum (Mo) | 0.20 - 0.30 |
| Aluminum (Al) | 0.020 - 0.035 |
| Copper (Cu) | ≤ 0.35 |
⚙️ Mechanical Properties
| Property | Value | Condition |
|---|---|---|
| Tensile Strength | 1280 - 1520 MPa | Quenched & Tempered |
| Yield Strength (0.2% offset) | 1080 - 1280 MPa | Quenched & Tempered |
| Elongation | 10 - 13% | In 50mm gauge length |
| Reduction of Area | 40 - 50% | Quenched & Tempered |
| Hardness (Brinell) | 262 - 321 HB | Annealed |
| Hardness (Rockwell C) | 38 - 45 HRC | Quenched & Tempered |
| Impact Energy (Charpy V-notch) | ≥ 54 J | At room temperature |
| Fatigue Limit | 620 - 690 MPa | 10&sup7; cycles |
| Modulus of Elasticity | 205 GPa | Typical value |
🔬 Physical Properties
| Property | Value | Temperature/Condition |
|---|---|---|
| Density | 7.85 g/cm³ | At 20°C |
| Melting Point | 1427 - 1482°C | Solidus - Liquidus |
| Thermal Conductivity | 44.5 W/m·K | At 100°C |
| Thermal Expansion Coefficient | 12.3×10-6/K | 20-100°C |
| Specific Heat Capacity | 475 J/kg·K | At 20°C |
| Electrical Resistivity | 0.23 µΩ·m | At 20°C |
| Magnetic Permeability | Ferromagnetic | Annealed condition |
| Curie Temperature | 770°C | Approximate |
| Poisson's Ratio | 0.27 - 0.30 | Elastic range |
📏 Product Specifications
| Specification | Available Options | Standards |
|---|---|---|
| Product Forms | Round bars, square bars, flat bars, plates, sheets, forgings, tubes | ASTM A29, A322, A331 |
| Round Bar Diameter | 6mm - 500mm | Hot rolled, cold drawn |
| Plate Thickness | 6mm - 200mm | ASTM A29, A322 |
| Length | Up to 12 meters | Custom lengths available |
| Surface Finish | Hot rolled, cold drawn, turned, ground, polished | Ra 0.8 - 12.5 µm |
| Dimensional Tolerance | ±0.1mm to ±3mm | Depending on form and size |
| Heat Treatment Condition | Annealed, normalized, quenched & tempered | Customer specified |
| International Standards | ASTM A29, SAE 4340, EN 1.6565, JIS SCM440 | Multiple certifications |
| Testing Certificates | Mill test certificate, material test report, 3.1 certificate | EN 10204 |
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Our Advantages in Processing AISI 4340
Advanced Vacuum Melting Technology
MetalZenith employs cutting-edge vacuum induction melting and electroslag remelting processes to produce AISI 4340 with exceptional cleanliness and homogeneity. Our controlled atmosphere processing eliminates harmful inclusions and ensures consistent chemical composition throughout the entire steel structure.
Precision Heat Treatment Capabilities
Our state-of-the-art heat treatment facilities feature computer-controlled furnaces with precise temperature monitoring and atmosphere control. This enables us to achieve optimal hardness, strength, and toughness combinations while maintaining dimensional stability and minimizing distortion.
Comprehensive Testing & Customization
MetalZenith offers complete customization services including specialized heat treatments, machining to near-net shape, and comprehensive material testing. Our in-house laboratory provides full chemical analysis, mechanical testing, and metallurgical evaluation to meet specific customer requirements.
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