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Technical Specifications
Product Overview
Metallurgical Characteristics
AISI 8740 is a low-alloy steel with a pearlitic-ferritic microstructure in the annealed condition. The addition of nickel, chromium, and molybdenum significantly enhances hardenability, allowing for through-hardening in larger sections. The nickel content improves toughness and impact resistance, while chromium contributes to hardenability and wear resistance. Molybdenum prevents temper brittleness and enhances high-temperature strength.
Heat Treatment Processes
MetalZenith employs precise heat treatment protocols for optimal performance. Normalizing is conducted at 870-900°C followed by air cooling. For hardening, the steel is austenitized at 845-870°C, quenched in oil or water, then tempered at 540-650°C depending on desired hardness. Our controlled atmosphere furnaces prevent decarburization and ensure uniform heating throughout the cross-section.
Manufacturing Process Excellence
Our manufacturing process begins with electric arc furnace melting using premium scrap and alloy additions. Secondary refining through ladle metallurgy and vacuum degassing removes harmful elements and inclusions. Continuous casting produces high-quality billets, which are hot rolled using computer-controlled rolling mills to achieve precise dimensions and mechanical properties. Cold drawing operations provide superior surface finish and dimensional accuracy.
Quality Standards & Testing
MetalZenith maintains comprehensive quality control throughout production. Chemical analysis is performed using optical emission spectroscopy and combustion analysis. Mechanical testing includes tensile, impact, and hardness testing per ASTM standards. Non-destructive testing includes ultrasonic inspection for internal soundness and magnetic particle inspection for surface defects. All products are supplied with certified test reports and material traceability documentation.
🧪 Chemical Composition
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.38 - 0.43 |
| Manganese (Mn) | 0.75 - 1.00 |
| Silicon (Si) | 0.20 - 0.35 |
| Phosphorus (P) | ≤ 0.035 |
| Sulfur (S) | ≤ 0.040 |
| Chromium (Cr) | 0.40 - 0.60 |
| Nickel (Ni) | 0.40 - 0.70 |
| Molybdenum (Mo) | 0.20 - 0.30 |
| Copper (Cu) | ≤ 0.35 |
| Iron (Fe) | Balance |
⚙️ Mechanical Properties
| Property | Value | Condition |
|---|---|---|
| Tensile Strength | 1030 - 1380 MPa | Quenched & Tempered |
| Yield Strength (0.2% offset) | 895 - 1240 MPa | Quenched & Tempered |
| Elongation | 12 - 17% | In 50mm gauge length |
| Reduction of Area | 40 - 55% | Quenched & Tempered |
| Hardness (Brinell) | 302 - 388 HB | Quenched & Tempered |
| Impact Energy (Charpy V-notch) | ≥ 54 J | At room temperature |
| Fatigue Limit | 515 - 690 MPa | 10&sup7; cycles |
| Modulus of Elasticity | 200 - 210 GPa | Typical value |
🔬 Physical Properties
| Property | Value | Temperature/Condition |
|---|---|---|
| Density | 7.85 g/cm³ | At 20°C |
| Melting Point | 1420 - 1460°C | Solidus - Liquidus |
| Thermal Conductivity | 42.7 W/m·K | At 20°C |
| Thermal Expansion Coefficient | 12.3×10-6/K | 20-100°C |
| Specific Heat Capacity | 460 J/kg·K | At 20°C |
| Electrical Resistivity | 0.28 µΩ·m | At 20°C |
| Magnetic Permeability | Ferromagnetic | Annealed condition |
| Curie Temperature | 770°C | Approximate |
📏 Product Specifications
| Specification | Available Options | Standards |
|---|---|---|
| Product Forms | Round bars, square bars, flat bars, plates, sheets, forgings, tubes | ASTM A322, A331, A505 |
| Round Bar Diameter | 6mm - 500mm | Hot rolled, cold drawn |
| Plate Thickness | 5mm - 200mm | Hot rolled, normalized |
| Length | Up to 12 meters | Custom cutting available |
| Surface Finish | Hot rolled, cold drawn, turned, ground, polished | Ra 0.8 - 12.5 µm |
| Dimensional Tolerance | h9 to h11 (cold drawn), ±1-3mm (hot rolled) | ISO 2768, DIN 1013 |
| Heat Treatment Condition | Annealed, normalized, quenched & tempered | Customer specified |
| International Equivalents | 40NiCrMo7 (EN), SCM440 (JIS), 40KhNMA (GOST) | Cross-reference standards |
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Our Advantages in Processing AISI 8740
Advanced Vacuum Melting Technology
MetalZenith employs cutting-edge vacuum induction melting and electroslag remelting processes to produce AISI 8740 with exceptional cleanliness and homogeneity. Our controlled atmosphere melting eliminates harmful inclusions and ensures consistent chemical composition throughout the entire heat, resulting in superior mechanical properties and enhanced fatigue resistance.
Precision Heat Treatment & Quality Control
Our state-of-the-art heat treatment facilities feature computer-controlled furnaces with precise temperature monitoring and automated quenching systems. Every batch undergoes comprehensive testing including tensile testing, hardness verification, impact testing, and ultrasonic inspection to guarantee consistent quality and performance that exceeds industry standards.
Custom Processing & Global Supply Chain
MetalZenith offers comprehensive customization services including precision machining, surface treatments, and specialized heat treatment cycles tailored to specific applications. Our global distribution network and strategic inventory locations ensure rapid delivery worldwide, while our technical support team provides engineering assistance for optimal material selection and processing.
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