AISI 4640 Steel Seamless tube (UNS G46400)

AISI 4640 Steel Seamless tube (UNS G46400) Product Information -:- For detailed product information, please contact sales. -: AISI 4640 Steel Seamless tube (UNS G46400) Synonyms -:- For detailed product information, please contact sales. -:

AISI 4640 Steel (UNS G46400) Product Information -:- For detailed product information, please contact sales. -: # **AISI 4640 Alloy Steel (UNS G46400)** ## **Medium Carbon Nickel-Molybdenum Through-Hardening Steel** --- ### **1. PRODUCT OVERVIEW** **AISI 4640 Alloy Steel (UNS G46400)** - **Material Classification:** Medium-carbon nickel-molybdenum alloy steel - **Primary Application:** Through-hardening (quenching and tempering) - **Carbon Content:** 0.38-0.43% (medium-high carbon range) - **Key Alloying Elements:** Nickel (0.70-1.00%) + Molybdenum (0.15-0.25%) - **Material Family:** AISI/SAE 46xx series (nickel-molybdenum steels) - **"40" Designation:** Nominal carbon content of approximately 0.40% - **UNS Designation:** G46400 (Standard), H46400 (Hardenability controlled) - **Typical Forms:** Rounds, flats, squares, forgings, billets **Material Characteristics:** 1. **Higher Carbon Content:** Provides excellent hardenability and wear resistance 2. **Moderate Nickel Level:** Lower than 4340 but provides good toughness 3. **Balanced Molybdenum:** Provides grain refinement and tempering stability 4. **Cost-Effective Alternative:** To 4340 with similar properties at lower nickel content 5. **Versatile Applications:** Suitable for both general and critical engineering uses --- ### **2. CHEMICAL COMPOSITION SPECIFICATION** | Element | AISI 4640 Standard Range (%) | Typical Aim Composition (%) | Metallurgical Function | |---------|-----------------------------|-----------------------------|------------------------| | **Carbon (C)** | 0.38-0.43 | 0.40-0.42 | Primary strengthener, determines hardness and hardenability | | **Manganese (Mn)** | 0.75-1.00 | 0.85-0.95 | Enhances hardenability, solid solution strengthening | | **Phosphorus (P)** | ≤ 0.035 | ≤ 0.020 | Residual impurity (controlled) | | **Sulfur (S)** | ≤ 0.040 | 0.020-0.035 | Machinability enhancer, typically at controlled levels | | **Silicon (Si)** | 0.15-0.30 | 0.20-0.25 | Deoxidizer, improves strength and temper resistance | | **Nickel (Ni)** | 0.70-1.00 | 0.80-0.90 | **Primary alloy:** Provides toughness and hardenability | | **Molybdenum (Mo)** | 0.15-0.25 | 0.18-0.22 | **Secondary alloy:** Grain refinement, prevents temper embrittlement | | **Chromium (Cr)** | - | ≤ 0.20 | Trace residual (not specified) | | **Copper (Cu)** | - | ≤ 0.35 | Trace residual | | **Iron (Fe)** | Balance | Balance | Matrix element | **Composition Design Philosophy:** - **Carbon Optimization:** 0.40% nominal provides excellent hardenability and strength - **Nickel Reduction:** Lower than 4340 (0.9% vs 1.8%) for cost optimization while maintaining toughness - **Manganese Enhancement:** Higher than 4600 series for improved hardenability - **Economic Balance:** Provides 4340-like properties at reduced alloy cost --- ### **3. INTERNATIONAL STANDARDS & EQUIVALENTS** | Standard System | Designation | Title / Description | Notes | |----------------|-------------|---------------------|-------| | **UNS** | G46400 | Unified Numbering System | Primary US designation | | **AISI/SAE** | 4640 | SAE J404, J412 | Original specification | | **ASTM** | A322 | Standard Specification for Steel Bars, Alloy | Grade 4640 | | **ASTM** | A29/A29M | Steel Bars, Carbon and Alloy | General requirements | | **ASTM** | A519 | Seamless Carbon and Alloy Steel Mechanical Tubing | Tubing applications | | **AMS** | 6427 | Steel Bars, Forgings, and Tubing | Aerospace specification | | **ISO** | 683-11 | Heat-treatable steels | International classification | | **DIN** | 1.6560 | 40NiCrMo6 | German equivalent | | **EN** | 1.6560 | 40NiCrMo6 | European designation | | **JIS** | SNCM439 | Nickel-chromium-molybdenum steel | Japanese similar grade | | **GB** | 40Ni2Mo | Chinese standard | Chinese equivalent | **H-Grade Availability:** - **AISI 4640H:** Hardenability controlled version - **Complies with:** SAE J1268 and ASTM A304 - **Typical bands:** Bands 2-4 depending on application requirements --- ### **4. PHYSICAL PROPERTIES** | Property | Value | Conditions / Notes | |----------|-------|-------------------| | **Density** | 7.85 g/cm³ (0.284 lb/in³) | At 20°C | | **Melting Range** | 1475-1515°C | Liquidus to solidus temperature | | **Thermal Conductivity** | 41.0 W/m·K | At 100°C, annealed condition | | **Specific Heat Capacity** | 460 J/kg·K | At 20°C | | **Coefficient of Thermal Expansion** | 12.0 × 10⁻⁶/K | 20-100°C temperature range | | **Electrical Resistivity** | 0.25 μΩ·m | At 20°C | | **Modulus of Elasticity** | 205 GPa (29.7×10⁶ psi) | Typical for steel | | **Shear Modulus** | 80 GPa (11.6×10⁶ psi) | - | | **Poisson's Ratio** | 0.29 | Standard value for steel | | **Magnetic Properties** | Ferromagnetic | Below Curie temperature (~770°C) | **Transformation Temperatures:** - **Ac₁:** ~720°C (1330°F) - **Ac₃:** ~780°C (1435°F) - **Ms (Martensite Start):** ~320°C (610°F) - **Mf (Martensite Finish):** ~180°C (355°F) --- ### **5. MECHANICAL PROPERTIES (HEAT TREATED CONDITION)** #### **Typical Properties After Standard Heat Treatment:** *845°C (1550°F) Austenitize, Oil Quench, 540°C (1000°F) Temper* | Property | Value Range | Testing Standard | Application Significance | |----------|-------------|------------------|--------------------------| | **Tensile Strength** | 1100-1300 MPa (160-189 ksi) | ASTM E8/E8M | High strength capability | | **Yield Strength (0.2%)** | 950-1150 MPa (138-167 ksi) | ASTM E8/E8M | Excellent resistance to deformation | | **Elongation in 4D** | 12-16% | ASTM E8/E8M | Moderate ductility for high-strength material | | **Reduction of Area** | 35-45% | ASTM E8/E8M | Good energy absorption capability | | **Hardness** | 32-38 HRC (302-352 HB) | ASTM E18/E10 | Balanced hardness for many applications | | **Charpy V-Notch Impact** | 25-40 J (18-30 ft-lb) | ASTM E23 | Moderate toughness, suitable for impact applications | | **Fatigue Strength (Rotating Bending)** | 550-650 MPa | - | Good fatigue resistance | | **Endurance Limit (approx.)** | 50-55% of UTS | - | Typical for quenched and tempered steels | #### **Properties by Tempering Temperature:** | Tempering Temperature | Hardness (HRC) | Tensile Strength (MPa) | Yield Strength (MPa) | Impact Energy (J) | |----------------------|----------------|------------------------|----------------------|------------------| | **200°C (390°F)** | 50-54 | 1600-1800 | 1400-1600 | 15-25 | | **425°C (800°F)** | 42-46 | 1300-1450 | 1150-1300 | 25-35 | | **540°C (1000°F)** | 32-36 | 1100-1250 | 950-1100 | 30-40 | | **650°C (1200°F)** | 26-30 | 850-950 | 700-800 | 40-50 | --- ### **6. HEAT TREATMENT RESPONSE** #### **Recommended Heat Treatment Parameters:** 1. **Annealing (Full):** - Temperature: 830-850°C (1525-1560°F) - Cooling: Furnace cool to 600°C at ≤25°C/hour, then air cool - Resulting Hardness: 187-229 HB 2. **Normalizing:** - Temperature: 870-900°C (1600-1650°F) - Cooling: Air cool - Purpose: Grain refinement, homogenization 3. **Hardening (Austenitizing):** - Temperature: 830-850°C (1525-1560°F) - Soak Time: 30 minutes per inch of thickness - Quenching Medium: Oil (standard), water for smaller sections - Critical Cooling Rate: Good due to carbon and alloy content 4. **Tempering:** - Temperature Range: 200-650°C (390-1200°F) - Time: 1-2 hours per inch of thickness - Cooling: Air cool (water or oil cooling may be used) #### **Hardenability Characteristics (Jominy Test - Typical):** | Distance from Quenched End | Hardness (HRC) | Microstructure | |----------------------------|----------------|---------------| | **1.5 mm (1/16 inch)** | 52-56 | 95-100% martensite | | **5 mm (3/16 inch)** | 46-50 | 85-95% martensite | | **10 mm (3/8 inch)** | 40-44 | 70-85% martensite | | **15 mm (5/8 inch)** | 34-38 | 50-70% martensite | | **25 mm (1 inch)** | 30-34 | 30-50% martensite | **Through-Hardening Capability:** - **Ideal Critical Diameter (Dᵢ):** ~50-75mm (2-3 inches) in oil - **Maximum Effective Hardening Depth:** ~40mm (1.5 inches) for 50 HRC - **Section Sensitivity:** Good - suitable for medium to large components - **Hardenability Index:** Similar to 4140 with better toughness --- ### **7. TYPICAL APPLICATIONS** #### **Automotive Components:** - **Transmission Parts:** Gears, shafts, synchronizer components - **Steering Components:** Steering knuckles, pitman arms, shafts - **Engine Components:** Crankshafts (medium duty), camshafts, connecting rods - **Drive Train:** Axle shafts, drive shafts, universal joints - **Suspension Parts:** Torsion bars, spring components, sway bars #### **Industrial Machinery:** - **Gear Manufacturing:** Industrial gears, pinions, heavy-duty gear blanks - **Power Transmission:** Couplings, sprockets, chain wheels, driveshafts - **Heavy Equipment:** Excavator pins, bucket teeth, track links, hydraulic rods - **Machine Tools:** Spindles, arbors, tool holders, lathe centers, milling machine parts - **Agricultural Machinery:** Plow shares, cultivator teeth, gearbox components #### **Construction and Mining:** - **Earth-Moving Equipment:** Wear plates, cutting edges, bucket adapters - **Mining Tools:** Drill bits, cutter teeth, crusher parts, mining shovel components - **Material Handling:** Conveyor components, bucket teeth, crane hooks #### **Oil and Gas Industry:** - **Drill String Components:** Tool joints, subs, stabilizers - **Valve Components:** Stems, gates, bodies for high-pressure service - **Pump Parts:** Shafts, impellers, liners - **Wellhead Equipment:** Mandrels, hangers, seals #### **General Engineering:** - **Fasteners:** High-strength bolts, studs, anchor bolts (Grade 10.9+ equivalent) - **Shafting:** General purpose shafts and axles for heavy machinery - **Wear Parts:** Components requiring high wear resistance and strength - **Tooling:** Die components, molds, jigs, fixtures --- ### **8. PROCESSING CHARACTERISTICS** #### **Machinability:** - **Relative Rating:** 50-55% of B1112 free-cutting steel (annealed condition) - **Annealed Condition Hardness:** 187-229 HB (optimal for machining) - **Hardened Condition Machinability:** 35-40% (requires carbide tools) - **Recommended Cutting Parameters:** - Annealed: 30-50 m/min with HSS tools - Hardened: 20-35 m/min with carbide tools - Feed rates: 0.10-0.20 mm/rev for finishing - Depth of cut: 1-4 mm optimal - **Tool Materials:** Carbide recommended for production - **Chip Formation:** Continuous to segmented chips depending on condition #### **Forming and Forging:** - **Hot Working Temperature:** 1150-900°C (2100-1650°F) - **Forgeability:** Good - suitable for most forging operations - **Cold Formability:** Limited in annealed condition - **Annealing Recommended:** Between forming operations if severe deformation #### **Welding Characteristics:** - **Weldability Rating:** Poor (requires significant precautions) - **Preheat Temperature:** 200-300°C (400-570°F) for thickness >12mm - **Post-Weld Heat Treatment:** Stress relief at 590-650°C (1100-1200°F) mandatory - **Recommended Methods:** GTAW (TIG), SMAW with low-hydrogen electrodes - **Filler Material:** AWS E11018-D2 or matching composition - **Critical Considerations:** High carbon content increases cracking susceptibility #### **Grinding and Finishing:** - **Grindability:** Good with proper wheel selection - **Surface Finishing:** Responds well to polishing and superfinishing - **Plating/Coating Compatibility:** Good base for various surface treatments - **Heat Generation Control:** Important to avoid tempering during grinding --- ### **9. MICROSTRUCTURAL CHARACTERISTICS** #### **As-Annealed Condition:** - **Primary Phase:** Ferrite with spheroidized carbides - **Grain Size:** ASTM 5-7 (fine to medium grain) - **Carbide Distribution:** Uniformly dispersed fine carbides - **Band Structure:** Minimal due to controlled processing #### **As-Quenched (Hardened):** - **Matrix:** Martensite (primarily lath type with some plate martensite) - **Retained Austenite:** <5% (typical) - **Prior Austenite Grain Size:** ASTM 7-8 (fine) - **Carbide Dissolution:** Complete during proper austenitizing #### **Tempered Condition:** - **Matrix:** Tempered martensite - **Carbide Precipitation:** Fine alloy carbides within martensite laths - **Tempering Stages:** Well-defined transformation stages - **Tempered Martensite Embrittlement:** Minimal due to molybdenum content --- ### **10. QUALITY ASSURANCE AND TESTING** #### **Standard Testing Requirements:** 1. **Chemical Analysis:** Spectrographic analysis per heat/lot (ASTM E415) 2. **Mechanical Testing:** Tensile and hardness tests (ASTM E8, E18) 3. **Microstructural Examination:** Grain size, cleanliness (ASTM E112, E45) 4. **Non-Destructive Testing:** As required by specification 5. **Hardenability Testing:** For H-grades per ASTM A255 #### **Inclusion Rating (Typical):** | Inclusion Type | ASTM E45 Rating (Worst Field) | Typical Value | |----------------|-------------------------------|---------------| | **A (Sulfide)** | ≤ 2.0 | 1.0-1.5 | | **B (Alumina)** | ≤ 1.5 | 0.5-1.0 | | **C (Silicate)** | ≤ 1.5 | 0.5-1.0 | | **D (Globular Oxide)** | ≤ 1.5 | 0.5-1.0 | #### **Certification Levels:** - **Standard Mill Certificate:** Chemical composition and hardness - **Test Certificate 3.1:** Includes mechanical property testing - **H-Grade Certification:** Includes Jominy hardenability curve - **Special Testing:** Additional tests as specified by customer --- ### **11. COMPARISON WITH SIMILAR GRADES** | Grade | C% Range | Ni% Range | Mo% Range | Typical UTS (MPa) | Hardness after 540°C temper | Primary Distinction | |-------|----------|-----------|-----------|-------------------|-----------------------------|---------------------| | **AISI 4640** | 0.38-0.43 | 0.70-1.00 | 0.15-0.25 | 1100-1300 | 32-38 HRC | Cost-effective high strength | | **AISI 4340** | 0.38-0.43 | 1.65-2.00 | 0.20-0.30 | 1200-1400 | 34-40 HRC | Higher toughness (more nickel) | | **AISI 4140** | 0.38-0.43 | - | 0.15-0.25 | 1100-1300 | 32-38 HRC | No nickel, lower toughness | | **AISI 8640** | 0.38-0.43 | 0.40-0.70 | 0.15-0.25 | 1100-1300 | 32-38 HRC | Lower nickel than 4640 | | **AISI 1045** | 0.43-0.50 | - | - | 700-850 | 25-30 HRC | Plain carbon, lower hardenability | **Selection Guidelines:** - **Choose 4640 over 4340:** For cost-sensitive applications with good toughness requirements - **Choose 4640 over 4140:** When better impact resistance is needed - **Choose 4640 over 8640:** When higher nickel content is justified for toughness - **Choose 4640 over 1045:** When hardenability and strength are critical --- ### **12. DESIGN CONSIDERATIONS** #### **Strength Advantages:** 1. **Excellent Hardenability:** Suitable for sections up to 75mm diameter 2. **Good Toughness:** Nickel provides reasonable impact resistance 3. **Wear Resistance:** High carbon content provides good abrasion resistance 4. **Fatigue Resistance:** Suitable for cyclic loading applications #### **Design Limitations:** 1. **Corrosion Resistance:** Similar to plain carbon steel (requires protection) 2. **Maximum Service Temperature:** Approximately 400°C (750°F) continuous 3. **Notch Sensitivity:** Moderate to high - design with proper radii 4. **Weldability Constraints:** Requires significant precautions #### **Recommended Design Practices:** - **Section Size:** Optimal for 25-75mm diameter components - **Heat Treatment:** Through-harden for uniform properties - **Surface Finish:** Good surface finish improves fatigue life (1.6-3.2μm Ra recommended) - **Stress Concentrations:** Use generous fillet radii (minimum 3mm) - **Thread Design:** Use rolled threads for better fatigue performance #### **Design Parameters for Typical Applications:** | Application | Recommended Hardness (HRC) | Tempering Temperature | Surface Finish (Ra) | Key Considerations | |-------------|----------------------------|----------------------|---------------------|-------------------| | **General Gears** | 32-36 | 540°C | 1.6-3.2 μm | Good balance of strength and toughness | | **Shafts** | 30-34 | 560°C | 0.8-1.6 μm | Optimize for fatigue resistance | | **Wear Plates** | 38-42 | 425°C | 3.2-6.3 μm | Maximize surface hardness | | **Fasteners** | 34-38 | 500°C | 1.6-3.2 μm | Consider thread rolling after heat treatment | --- ### **13. ENVIRONMENTAL AND ECONOMIC CONSIDERATIONS** #### **Cost Factors:** - **Material Cost:** Medium (higher than plain carbon, lower than high-nickel grades) - **Processing Cost:** Standard heat treatment requirements - **Lifecycle Cost:** Good for medium to heavy-duty applications - **Availability:** Readily available from steel service centers #### **Environmental Aspects:** - **Recyclability:** 100% recyclable as steel scrap - **Production Energy:** Moderate (higher than plain carbon steels) - **Alternative Materials:** Consider 4140 for similar strength at potentially lower cost - **Sustainability:** Nickel and molybdenum are fully recyclable #### **Supply Chain Considerations:** - **Lead Times:** Typically available from stock for common sizes - **Global Availability:** Widely produced in US, Europe, and Asia - **Quality Consistency:** Good with reputable producers - **Certification Availability:** Full testing and certification readily available --- ### **14. TECHNICAL GUIDELINES** #### **Optimal Heat Treatment for Common Applications:** 1. **General Purpose Components:** 845°C oil quench + 540°C temper 2. **High Strength Applications:** 845°C oil quench + 425°C temper 3. **Maximum Toughness:** 845°C oil quench + 650°C temper 4. **Wear Resistance Focus:** 845°C oil quench + 200°C temper #### **Post-Heat Treatment Processing:** - **Stress Relieving:** Recommended after rough machining (550-650°C) - **Straightening:** May be required after heat treatment - **Final Machining:** Light finishing after heat treatment if needed - **Surface Treatments:** Nitriding, induction hardening, or coatings as required #### **Special Heat Treatment Considerations:** - **Austempering:** Possible for improved toughness in certain applications - **Marquenching:** Can reduce distortion in complex shapes - **Cryogenic Treatment:** Optional for retained austenite transformation - **Multiple Tempering:** Sometimes used for stress relief and property optimization --- **MATERIAL SELECTION SUMMARY:** AISI 4640 (UNS G46400) represents an economically optimized high-strength alloy steel that balances performance with cost. With its medium-high carbon content (0.38-0.43%) and moderate nickel level (0.70-1.00%), it provides excellent hardenability, good strength, and reasonable toughness. This makes it particularly suitable for components requiring high strength and wear resistance where the premium cost of higher-nickel grades like 4340 cannot be justified. **KEY ADVANTAGES:** 1. **Excellent Hardenability:** Good through-hardening capability 2. **Cost Effective:** Lower nickel content than 4340 reduces material cost 3. **Good Strength-Toughness Balance:** Suitable for impact applications 4. **Versatile Applications:** Wide range of industrial and automotive uses **HEAT TREATMENT RECOMMENDATION:** For optimal performance with AISI 4640: 1. Austenitize at 830-850°C (1525-1560°F) with adequate soak time 2. Oil quench for sections up to 75mm diameter 3. Temper according to required property balance (typically 425-600°C) 4. Consider stress relieving after rough machining if dimensional stability is critical 5. For maximum properties, consider double tempering at 25°C above initial temper --- **QUALITY ASSURANCE STATEMENT:** AISI 4640 alloy steel is produced to meet or exceed the requirements of SAE J404/J412 and ASTM A322. For critical applications, specify additional testing requirements such as microcleanliness rating, grain size verification, non-destructive examination, or H-grade certification for hardenability control. **DISCLAIMER:** The information provided represents typical properties and characteristics based on standard specifications. Actual values may vary within acceptable specification ranges. For critical applications, material testing and validation are essential. Consultation with qualified materials engineering professionals is recommended for specific application requirements. Proper heat treatment procedures must be followed to achieve specified properties. Always verify material certification and test reports upon receipt for critical applications. -:- For detailed product information, please contact sales. -: AISI 4640 Steel (UNS G46400) Specification Dimensions Size： Diameter 20-1000 mm Length <4079 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 4640 Steel (UNS G46400) Properties -:- For detailed product information, please contact sales. -:

Applications of AISI 4640 Steel Seamless tube (UNS G46400) -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI 4640 Steel Seamless tube (UNS G46400) -:- For detailed product information, please contact sales. -:

Packing of AISI 4640 Steel Seamless tube (UNS G46400) -:- 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 Seamless tube 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 550 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