AISI 8740H Steel, normalized

AISI 8740H Steel, normalized 870°C (1600°F) Product Information -:- For detailed product information, please contact sales. -: AISI 8740H Steel, normalized 870°C (1600°F) Synonyms -:- For detailed product information, please contact sales. -:

AISI 8740H Steel, normalized 870°C (1600°F) Product Information -:- For detailed product information, please contact sales. -: **Technical Specification: AISI 8740H Steel – Normalized Condition** --- ### **1. MATERIAL IDENTIFICATION & SPECIFICATION** * **Standard Designation:** AISI 8740H / SAE 8740H * **UNS Number:** G87401 * **Material Type:** Hardenability-Banded Chromium-Molybdenum-Nickel Alloy Steel * **Condition:** Normalized at 870°C (1600°F) * **Key Feature:** The "H" suffix indicates the steel is produced to meet specific hardenability requirements as per end-quench (Jominy) test bands defined in SAE J1268. **International/Regional Equivalents:** | Region/Standard | Designation | Note | |----------------|-------------|------| | **ASTM (USA)** | A304 (Standard for H-Grade Steel Bars) | Governs hardenability requirements | | **DIN (Germany)** | 1.6546 (41CrMo4) + Hardenability band | Similar chemistry, H-band equivalent | | **EN (Europe)** | 1.7225 (42CrMo4) + HL/HR/HH bands | EN 10083-3 defines hardenability classes | | **JIS (Japan)** | SCM440H | Japanese H-grade equivalent | | **GB (China)** | 42CrMoH | Chinese H-grade designation | --- ### **2. CHEMICAL COMPOSITION (Weight %)** The chemical composition for 8740H is controlled within broader ranges than standard 8740 to ensure consistent hardenability across production heats. | Element | AISI/SAE 8740H Range (%) | Primary Function | |---------|--------------------------|------------------| | **Carbon (C)** | 0.37 - 0.44 | Base strength and hardenability control element | | **Manganese (Mn)** | 0.65 - 1.10 | Enhances hardenability and strength | | **Silicon (Si)** | 0.15 - 0.35 | Deoxidizer, increases strength | | **Chromium (Cr)** | 0.35 - 0.65 | Improves hardenability and wear resistance | | **Nickel (Ni)** | 0.35 - 0.75 | **Critical for toughness enhancement** | | **Molybdenum (Mo)** | 0.15 - 0.30 | Promotes deep hardening and temper resistance | | **Phosphorus (P)** | ≤ 0.025 | Impurity control for toughness | | **Sulfur (S)** | ≤ 0.025 | Impurity control for machinability | | **Iron (Fe)** | Balance | Base element | **H-Grade Significance:** The "H" designation means purchasers can specify material based on **Jominy hardenability test results** rather than strict chemical limits, ensuring consistent heat treatment response regardless of minor chemistry variations within the specified bands. --- ### **3. NORMALIZING HEAT TREATMENT** * **Process:** Normalizing at 870°C (1600°F) * **Procedure:** 1. Heat uniformly to 870°C ± 15°C (1600°F ± 25°F) 2. Soak for approximately 1 hour per 25 mm (1 inch) of thickness 3. Cool in still air to room temperature * **Metallurgical Purpose:** - Refine grain structure after hot working - Improve microstructural homogeneity - Relieve internal stresses - Enhance machinability and dimensional stability - Prepare for subsequent heat treatment * **Resulting Microstructure:** Fine-grained ferrite-pearlite structure with uniform distribution --- ### **4. MECHANICAL PROPERTIES (Normalized Condition)** | Property | Typical Value | Test Standard | |----------|---------------|---------------| | **Tensile Strength** | 620 - 800 MPa (90-116 ksi) | ASTM E8 | | **Yield Strength (0.2% offset)** | 380 - 550 MPa (55-80 ksi) | ASTM E8 | | **Elongation** | 18-24% | ASTM E8 | | **Reduction of Area** | 45-60% | ASTM E8 | | **Hardness** | 197-241 HBW (92-100 HRB) | ASTM E10/E18 | | **Charpy V-Notch Impact** | 40-70 J (30-52 ft·lb) at 21°C | ASTM E23 | **Note:** These are typical properties in the normalized condition. Final properties are achieved through subsequent quenching and tempering. --- ### **5. HARDENABILITY DATA (Jominy End-Quench)** 8740H is supplied with guaranteed hardenability bands. Typical Jominy curve characteristics: | Distance from Quenched End | Hardness Range (HRC) | |----------------------------|----------------------| | 1/16 inch (1.6 mm) | 48-55 | | 1/4 inch (6.4 mm) | 45-52 | | 1/2 inch (12.7 mm) | 38-46 | | 1 inch (25.4 mm) | 30-38 | | 2 inches (50.8 mm) | 25-32 | **Hardenability Bands:** Material is supplied to specific "H-bands" (e.g., H-band minimum and maximum curves) as agreed between purchaser and supplier per SAE J1268. --- ### **6. PHYSICAL PROPERTIES** | Property | Value @ 20°C (68°F) | |----------|---------------------| | **Density** | 7.85 g/cm³ (0.284 lb/in³) | | **Modulus of Elasticity** | 205 GPa (29,700 ksi) | | **Poisson's Ratio** | 0.29 | | **Thermal Conductivity** | 41.8 W/m·K | | **Specific Heat Capacity** | 460 J/kg·K | | **Coefficient of Thermal Expansion** | 12.2 × 10⁻⁶/K (20-100°C) | | **Magnetic Properties** | Ferromagnetic | --- ### **7. PROCESSING CHARACTERISTICS** **Machinability (Normalized Condition):** - **Machinability Rating:** 60% (compared to 100% for 1212 steel) - **Recommended Cutting Speeds:** 30-45 m/min (100-150 ft/min) for turning - **Tool Materials:** Carbide or high-speed steel with positive rake angles - **Chip Formation:** Continuous chips; chip breakers recommended **Weldability:** - **Weldability Rating:** Fair to Good (with precautions) - **Preheat Temperature:** 150-200°C (300-400°F) recommended - **Post-Weld Heat Treatment:** Recommended for critical applications - **Suitable Processes:** SMAW, GTAW, GMAW with low-hydrogen electrodes **Forging:** - **Hot Working Temperature:** 1150-900°C (2100-1650°F) - **Finishing Temperature:** ≥ 850°C (1560°F) - **Annealing Required:** After forging to restore machinability --- ### **8. TYPICAL APPLICATIONS** **Aerospace & Defense:** - Landing gear components (in normalized state prior to final heat treatment) - Engine mounts and structural fittings - Helicopter transmission components - Missile and rocket motor cases **Automotive & Transportation:** - High-strength gears and pinions - Crankshafts and camshafts - Axle shafts and drive components - Heavy-duty suspension parts **Industrial Machinery:** - Large gear blanks for power transmission - Machine tool components (shafts, spindles) - Hydraulic cylinder rods and pistons - Mining and construction equipment parts **Oil & Gas Industry:** - Drill collar components - Tool joints and subs - Valve bodies and stems - Wellhead equipment **Additional Applications:** - High-strength fasteners and bolts - Marine shafting and propeller components - Agricultural equipment gears and shafts - Crane and hoist components --- ### **9. HEAT TREATMENT AFTER NORMALIZING** Normalized 8740H is typically further processed to achieve final properties: | Subsequent Treatment | Resulting Hardness | Applications | |----------------------|-------------------|--------------| | **Quench & Temper (425-650°C)** | 25-45 HRC | General high-strength components | | **Carburizing** | Case: 58-63 HRC | Wear-resistant surfaces | | **Induction Hardening** | 50-58 HRC | Localized wear resistance | | **Nitriding** | Surface: 65-72 HRC | High-wear, low-distortion parts | --- ### **10. QUALITY ASSURANCE & TESTING** **Standard Testing Requirements:** - Chemical analysis (each heat) - Hardenability test (Jominy) per ASTM A255 - Mechanical property verification - Macroetch test for soundness (if specified) **Optional/Nondestructive Testing:** - Ultrasonic testing per ASTM A388 - Magnetic particle inspection per ASTM E709 - Dye penetrant inspection per ASTM E165 **Certification:** - Mill Test Certificate per EN 10204 3.1 or 3.2 - Material Test Report with full traceability - Hardenability certification per SAE J1268 --- ### **11. DESIGN & SELECTION CONSIDERATIONS** **Advantages of 8740H in Normalized Condition:** 1. **Consistent Heat Treatment Response:** Guaranteed hardenability ensures uniform properties after quenching 2. **Excellent Machinability:** Normalized structure provides optimal condition for machining 3. **Good Weldability:** Suitable for fabricated components requiring post-weld heat treatment 4. **Versatile Applications:** Wide range of achievable final properties through different heat treatments 5. **Cost-Effective:** H-grade specification reduces quality assurance costs through predictable performance **Limitations:** - Not suitable for high-temperature service (>400°C/750°F) - Requires corrosion protection in aggressive environments - Higher cost than carbon steels **Design Recommendations:** - Specify hardenability band requirements based on section size - Consider subsequent heat treatment in design tolerances - Allow for decarburization removal in machined surfaces - Design for uniform section thickness where possible --- ### **12. ORDERING INFORMATION** When ordering AISI 8740H normalized material, specify: 1. **Material Designation:** AISI 8740H, Normalized 2. **Dimensions and Tolerances** 3. **Hardenability Requirements:** Specific Jominy band or minimum/maximum values at specified positions 4. **Testing and Certification:** Required tests and certificate type 5. **Special Requirements:** NDT, straightness, surface condition 6. **Quantity and Packaging** **Example Order Specification:** - AISI 8740H Round Bar, Normalized at 870°C - Diameter: 50mm ±0.5mm, Length: 3000mm ±10mm - Hardenability: To SAE J1268 Band Limits - Certification: EN 10204 3.1 with chemical analysis and Jominy test report - Surface: Descaled, ends square cut --- ### **13. TECHNICAL NOTES** 1. **Hardenability Control:** The "H" designation ensures that material from different heats will respond similarly to heat treatment, critical for large production runs. 2. **Normalizing Benefits:** Normalizing provides more consistent properties than as-rolled material and better machinability than annealed material for many applications. 3. **Nickel Content:** The nickel content (0.35-0.75%) provides superior toughness compared to nickel-free grades like 4140H. 4. **Section Size Limitations:** Final achievable properties after quenching depend on section size; consult hardenability data for specific applications. 5. **Quality Grades:** Available in commercial quality, aircraft quality (AMS), and special quality grades with varying levels of testing and inspection. --- **Disclaimer:** This technical data sheet provides typical values and characteristics. Actual properties may vary based on manufacturing processes, heat treatment parameters, and section size. For critical applications, conduct appropriate testing and consult with materials engineering specialists. Always refer to the latest edition of relevant standards and specifications. -:- For detailed product information, please contact sales. -: AISI 8740H Steel, normalized 870°C (1600°F) Specification Dimensions Size： Diameter 20-1000 mm Length <6385 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 8740H Steel, normalized 870°C (1600°F) Properties -:- For detailed product information, please contact sales. -:

Applications of AISI 8740H Steel, normalized 870°C (1600°F) -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI 8740H Steel, normalized 870°C (1600°F) -:- For detailed product information, please contact sales. -:

Packing of AISI 8740H Steel, normalized 870°C (1600°F) -:- 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 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 2856 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