AISI 8740H Steel, annealed

AISI 8740H Steel, annealed 815°C (1500°F) Product Information -:- For detailed product information, please contact sales. -: AISI 8740H Steel, annealed 815°C (1500°F) Synonyms -:- For detailed product information, please contact sales. -:

AISI 8740H Steel, annealed 815°C (1500°F) Product Information -:- For detailed product information, please contact sales. -: # **Technical Specification: AISI 8740H Alloy Steel – Full Annealed Condition** ## **1. MATERIAL IDENTIFICATION** | **Property** | **Specification** | |--------------|-------------------| | **Standard Designation** | AISI 8740H / SAE 8740H | | **UNS Number** | G87401 | | **Material Type** | Hardenability-Banded Chromium-Molybdenum-Nickel Alloy Steel | | **Heat Treatment Condition** | Full Annealed at 815°C (1500°F) | | **Key Feature** | "H" suffix denotes guaranteed hardenability bands per SAE J1268/ASTM A304 | ### **International Standard Equivalents** | **Standard** | **Designation** | **Remarks** | |--------------|-----------------|-------------| | **ASTM (USA)** | A304 Grade 8740H | Hardenability specification | | **AMS (Aerospace)** | AMS 6320 (Annealed) | Aircraft quality | | **DIN (Germany)** | 1.6546H / 41CrMo4H | With Hardenability certification | | **EN (Europe)** | 1.7225H / 42CrMo4H | EN 10083-3, Hardenability class | | **JIS (Japan)** | SCM440H | Japanese H-grade equivalent | | **ISO** | 683-1 41CrMo4H | International standardization | --- ## **2. CHEMICAL COMPOSITION (Weight %)** AISI 8740H features controlled chemistry ranges to ensure consistent hardenability response within specified bands. | **Element** | **Min (%)** | **Max (%)** | **Optimal Range (%)** | **Metallurgical Function** | |-------------|-------------|-------------|----------------------|----------------------------| | **Carbon (C)** | 0.37 | 0.44 | 0.39-0.42 | Primary hardenability and strength element | | **Manganese (Mn)** | 0.65 | 1.10 | 0.75-0.95 | Austenite stabilizer, improves hardenability | | **Silicon (Si)** | 0.15 | 0.35 | 0.20-0.30 | Deoxidizer, solid solution strengthener | | **Chromium (Cr)** | 0.35 | 0.65 | 0.45-0.55 | Carbide former, improves wear resistance | | **Nickel (Ni)** | 0.35 | 0.75 | 0.45-0.65 | **Critical toughness enhancer**, austenite stabilizer | | **Molybdenum (Mo)** | 0.15 | 0.30 | 0.20-0.25 | Refines grain, prevents temper embrittlement | | **Phosphorus (P)** | - | 0.025 | ≤0.020 | Impurity control (toughness preservation) | | **Sulfur (S)** | - | 0.025 | 0.010-0.020 | Machinability improvement | | **Iron (Fe)** | Balance | - | - | Matrix element | **H-Grade Significance:** The "H" designation ensures predictable heat treatment response across different production batches through controlled hardenability rather than strict chemical composition limits. --- ## **3. ANNEALING HEAT TREATMENT** ### **Process Parameters** - **Annealing Temperature:** 815°C ± 15°C (1500°F ± 25°F) - **Soaking Time:** 1-2 hours per inch of thickness (minimum 2 hours) - **Cooling Rate:** Furnace cooling at ≤30°C/hour (55°F/hour) to 600°C (1110°F), then air cooling - **Atmosphere:** Protective (endothermic gas) to prevent decarburization ### **Metallurgical Objectives** 1. **Softening:** Achieve minimum hardness for optimal machinability 2. **Stress Relief:** Eliminate residual stresses from prior manufacturing 3. **Grain Refinement:** Produce uniform, equiaxed ferrite-pearlite microstructure 4. **Homogenization:** Ensure chemical and structural uniformity 5. **Dimensional Stability:** Minimize distortion during subsequent machining ### **Resulting Microstructure** - **Primary Phase:** Coarse, spheroidized cementite in ferrite matrix - **Grain Size:** ASTM 5-7 (fine to medium) - **Carbide Distribution:** Uniformly dispersed, well-spheroidized - **Phase Balance:** Approximately 40-50% ferrite, balance pearlite --- ## **4. MECHANICAL PROPERTIES (Annealed Condition)** ### **Typical Room Temperature Properties** | **Property** | **Value Range** | **Test Standard** | **Notes** | |--------------|----------------|-------------------|-----------| | **Hardness** | 149-187 HBW (80-90 HRB) | ASTM E10/E18 | Optimal for machining | | **Tensile Strength** | 515-655 MPa (75-95 ksi) | ASTM E8 | | | **Yield Strength (0.2%)** | 310-450 MPa (45-65 ksi) | ASTM E8 | | | **Elongation (50mm)** | 20-28% | ASTM E8 | Excellent ductility | | **Reduction of Area** | 50-65% | ASTM E8 | | | **Modulus of Elasticity** | 200-205 GPa (29,000-29,700 ksi) | ASTM E111 | | | **Charpy V-Notch Impact** | 35-60 J (26-44 ft·lb) @ 21°C | ASTM E23 | Good toughness | ### **Properties vs. Section Size** | **Section Diameter** | **Surface Hardness (HBW)** | **Core Hardness (HBW)** | **Tensile Strength (MPa)** | |----------------------|----------------------------|-------------------------|----------------------------| | ≤25 mm (1") | 165-187 | 165-187 | 590-655 | | 25-50 mm (1-2") | 159-179 | 157-177 | 550-620 | | 50-100 mm (2-4") | 152-172 | 149-169 | 525-590 | --- ## **5. PHYSICAL PROPERTIES** | **Property** | **Value @ 20°C (68°F)** | **Remarks** | |--------------|-------------------------|-------------| | **Density** | 7.85 g/cm³ (0.284 lb/in³) | Typical for alloy steels | | **Thermal Conductivity** | 42.0 W/m·K | At annealed condition | | **Specific Heat Capacity** | 460 J/kg·K | | | **Coefficient of Thermal Expansion** | 12.3 × 10⁻⁶/K (20-100°C) | Linear expansion | | **Electrical Resistivity** | 0.22 μΩ·m | | | **Magnetic Properties** | Ferromagnetic | Curie temp: ~770°C | | **Melting Range** | 1425-1510°C (2600-2750°F) | Solidus-Liquidus | --- ## **6. PROCESSING CHARACTERISTICS** ### **Machinability** - **Machinability Rating:** 65-70% (relative to B1112 = 100%) - **Optimal Cutting Speed:** 35-50 m/min (115-165 ft/min) for turning - **Recommended Feed Rate:** 0.15-0.30 mm/rev (0.006-0.012 in/rev) - **Tool Materials:** Carbide inserts (grades C5-C6) or coated HSS - **Chip Formation:** Continuous, ribbon-type chips (chip breakers recommended) - **Surface Finish:** Can achieve Ra 0.8-1.6 μm (32-63 μin) with proper technique ### **Formability** - **Cold Forming:** Good (with proper tooling and lubrication) - **Bend Radius:** Minimum 2× thickness for 90° bend - **Forging Temperature Range:** 1150-900°C (2100-1650°F) - **Hot Working:** Excellent above 950°C (1740°F) ### **Weldability** - **Weldability Rating:** Fair (Carbon Equivalent ≈ 0.75-0.85) - **Preheat Required:** 150-200°C (300-400°F) for thickness >12 mm - **Post-Weld Heat Treatment:** Recommended (stress relief at 595-650°C) - **Suitable Processes:** GTAW, GMAW (low-hydrogen), SMAW (E10018-D2) --- ## **7. HARDENABILITY CHARACTERISTICS** ### **Jominy End-Quench Test Results (Typical)** | **Distance from Quenched End** | **Hardness Range (HRC)** | **H-Band Specification** | |--------------------------------|--------------------------|--------------------------| | 1/16 inch (1.6 mm) | 50-56 | Min 48, Max 57 | | 1/4 inch (6.4 mm) | 47-52 | Min 44, Max 53 | | 1/2 inch (12.7 mm) | 40-46 | Min 37, Max 47 | | 1 inch (25.4 mm) | 32-38 | Min 29, Max 39 | | 2 inches (50.8 mm) | 26-32 | Min 23, Max 33 | **Note:** Actual hardenability bands are certified per customer requirements within SAE J1268 limits. ### **Section Size Limitations for Through-Hardening** | **Quenching Medium** | **Maximum Diameter for 50% Martensite** | **Maximum Diameter for 90% Martensite** | |----------------------|-----------------------------------------|----------------------------------------| | **Fast Oil** | 100-125 mm (4-5 inches) | 75-90 mm (3-3.5 inches) | | **Water** | 125-150 mm (5-6 inches) | 100-115 mm (4-4.5 inches) | | **Polymer Quench** | 90-110 mm (3.5-4.3 inches) | 65-80 mm (2.5-3.1 inches) | --- ## **8. TYPICAL APPLICATIONS** ### **Aerospace & Defense Applications** - **Landing Gear Components:** Forgings and machined parts prior to final heat treatment - **Engine Mounts and Brackets:** Complex shapes requiring extensive machining - **Helicopter Transmission Parts:** Gear blanks and housing components - **Missile Components:** Structural elements requiring precise machining ### **Automotive & Heavy Equipment** - **Transmission Gears:** High-precision gear blanks for automotive transmissions - **Crankshafts and Camshafts:** Forged blanks for high-performance engines - **Axle Shafts:** Heavy-duty axle components for trucks and off-road vehicles - **Steering Components:** Precision parts requiring complex machining ### **Industrial Machinery** - **Gear Blanks:** Large diameter gears for industrial drives - **Machine Tool Components:** Spindles, shafts, and precision parts - **Hydraulic Components:** Pump parts, valve bodies, cylinder rods - **Mining Equipment:** Wear parts requiring high toughness ### **Oil & Gas Industry** - **Drill String Components:** Tool joints, subs, and connectors - **Valve Components:** Gates, stems, and bodies for high-pressure service - **Wellhead Equipment:** Critical components requiring reliability ### **Additional Applications** - **High-Strength Fasteners:** Bolts, studs, and special fasteners - **Marine Components:** Shafting, propeller hubs, and fittings - **Agricultural Equipment:** Gears, shafts, and driveline components - **Construction Machinery:** Pins, bushings, and linkage components --- ## **9. SUBSEQUENT HEAT TREATMENT OPTIONS** ### **Recommended Heat Treatment Cycles** | **Treatment** | **Austenitizing** | **Quench Medium** | **Tempering Range** | **Resultant Hardness** | **Typical Applications** | |---------------|-------------------|-------------------|---------------------|------------------------|--------------------------| | **High Strength** | 830-850°C (1525-1560°F) | Fast Oil | 200-400°C (390-750°F) | 40-52 HRC | Gears, shafts, bearings | | **High Toughness** | 830-850°C (1525-1560°F) | Fast Oil | 540-650°C (1000-1200°F) | 25-35 HRC | Structural components | | **Case Hardening** | Carburize at 900-925°C (1650-1700°F) | Oil | 150-200°C (300-400°F) | Case: 58-63 HRC Core: 30-40 HRC | Wear surfaces | | **Induction Hardening** | 870-900°C (1600-1650°F) | Water spray | 150-200°C (300-400°F) | 50-58 HRC | Localized wear areas | ### **Heat Treatment Response** - **Critical Cooling Rate:** ~15°C/second (27°F/second) for 50% martensite - **Ms Temperature:** ~350°C (660°F) - **Mf Temperature:** ~200°C (390°F) - **Tempering Stability:** Good resistance to overtempering up to 400°C (750°F) --- ## **10. QUALITY ASSURANCE & TESTING** ### **Standard Testing Requirements** 1. **Chemical Analysis:** Per heat/lot (ASTM A751) 2. **Hardenability Test:** Jominy end-quench (ASTM A255) 3. **Mechanical Testing:** Tensile and hardness (ASTM A370) 4. **Macroetch Test:** For internal quality (ASTM E381) 5. **Grain Size:** ASTM E112 (typical 5-7) ### **Optional/Nondestructive Testing** - **Ultrasonic Testing:** ASTM A388 (for internal defects) - **Magnetic Particle Inspection:** ASTM E709 (surface cracks) - **Dye Penetrant Inspection:** ASTM E165 (surface defects) - **Decarburization Check:** ASTM E1077 ### **Certification Levels** - **Commercial Quality:** Standard MTR with chemistry and hardness - **Aircraft Quality:** AMS 6320 with full testing including Jominy - **Nuclear Quality:** Additional NDT and enhanced documentation - **Customer-Specific:** Tailored testing per drawing requirements --- ## **11. DESIGN & SELECTION GUIDELINES** ### **Advantages of Annealed 8740H** 1. **Superior Machinability:** Lowest possible hardness for complex machining 2. **Predictable Heat Treatment:** Guaranteed hardenability ensures consistent results 3. **Excellent Toughness Potential:** Nickel content enables high impact resistance 4. **Dimensional Stability:** Stress-relieved condition minimizes distortion 5. **Versatility:** Suitable for multiple final heat treatment paths ### **Design Considerations** - **Allow for Decarburization:** 0.25-0.50 mm (0.010-0.020 in) per side removal - **Section Uniformity:** Design for consistent wall thickness where possible - **Stress Concentrations:** Use generous fillet radii (minimum 3 mm) - **Heat Treatment Distortion:** Allow 0.1-0.2% dimensional change during hardening ### **Cost-Benefit Analysis** | **Factor** | **Advantage** | **Consideration** | |------------|---------------|-------------------| | **Material Cost** | Moderate | Higher than carbon steels, lower than premium alloys | | **Machining Cost** | Low | Excellent machinability reduces tooling and time | | **Heat Treatment Cost** | Moderate | Requires controlled atmosphere for best results | | **Performance Value** | High | Excellent strength-toughness combination | --- ## **12. ORDERING INFORMATION** ### **Minimum Order Specifications** ```plaintext 1. Material: AISI 8740H, Full Annealed at 815°C 2. Dimensions: [Specify diameter/thickness × length] 3. Quantity: [Number of pieces or weight] 4. Hardenability: [Specify Jominy band requirements] 5. Certification: [MTR type and testing requirements] 6. Surface Condition: [Black, descaled, rough turned, etc.] 7. Packaging: [Bundle, crate, special handling] ``` ### **Standard Delivery Conditions** - **Lead Time:** 4-8 weeks for standard sizes, 8-12 weeks for specials - **Minimum Order Quantity:** Typically 500 kg (1100 lb) for standard sizes - **Tolerances:** Per ASTM A29 or customer specification - **Marking:** Heat number, grade, size, and supplier identification ### **Special Requirements Availability** - **Enhanced Cleanliness:** Vacuum degassed, inclusion control - **Special Shapes:** Forged, rolled, or extruded to near-net shape - **Surface Protection:** Oiled, coated, or wrapped for corrosion protection - **Just-in-Time Delivery:** Scheduled deliveries to support production --- ## **13. TECHNICAL SUPPORT & RESOURCES** ### **Technical References** - **SAE J404:** Chemical Compositions - **SAE J1268:** Hardenability Bands - **ASTM A304:** H-Grade Steel Bars - **ASM Handbook Vol. 1:** Properties and Selection - **ASM Specialty Handbook:** Carbon and Alloy Steels ### **Industry Applications** - **Aerospace:** AMS specifications and NADCAP requirements - **Automotive:** SAE and AIAG standards - **Oil & Gas:** API and NACE specifications - **Nuclear:** ASME Section II and III requirements ### **Supplier Qualifications** - **ISO 9001:** Quality Management Systems - **AS9100:** Aerospace Quality Systems - **NADCAP:** Special Process Accreditation - **ISO/IEC 17025:** Testing Laboratory Competence --- ## **14. ENVIRONMENTAL & SAFETY INFORMATION** ### **Material Safety** - **Health Hazards:** Grinding dust may be hazardous if inhaled - **Fire Hazards:** Not flammable, but hot machining can generate sparks - **Disposal:** Recyclable as scrap steel - **Handling:** Use standard mechanical handling equipment ### **Sustainability** - **Recyclability:** 100% recyclable - **Energy Efficiency:** Can be produced with electric arc furnace technology - **Life Cycle:** Long service life reduces replacement frequency --- **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. The information contained herein is subject to change without notice and is provided for technical guidance only. -:- For detailed product information, please contact sales. -: AISI 8740H Steel, annealed 815°C (1500°F) Specification Dimensions Size： Diameter 20-1000 mm Length <6386 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, annealed 815°C (1500°F) Properties -:- For detailed product information, please contact sales. -:

Applications of AISI 8740H Steel, annealed 815°C (1500°F) -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI 8740H Steel, annealed 815°C (1500°F) -:- For detailed product information, please contact sales. -:

Packing of AISI 8740H Steel, annealed 815°C (1500°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 2857 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