AISI 4340 Steel Flange

1,We Manufacturing processes are primarily classified into four types: 1:Forging, 2:Casting, 3:Cutting, 4:Rolling. 2,We can manufacture in accordance with these standards. Standards: GB Series (Chinese Standards), JB Series (Machinery Standards), HG Series (Chemical Industry Standards), ASME B16.5 (American Standards), BS4504 (British Standards), DIN (German Standards), and JIS (Japanese Standards). Internationally, there are two primary systems of pipe flange standards: the European system, represented by the German DIN standards (including those of the former Soviet Union), and the American system, represented by the US ANSI pipe flange standards. Other common standards include: the Chinese Ministry of Machinery Industry standards (JB series), the Ministry of Chemical Industry standards (HG series), the Chinese National Standard *GB/T 9112–9124-2010 Steel Pipe Flanges*, as well as US standards (ASME B16.5), British standards (BS4504), German standards (DIN), Japanese standards (JIS), and marine standards (CBM), among others. The nominal pressure ratings for the PN series are designated by "PN" and comprise the following nine levels: PN2.5, PN6, PN10, PN16, PN25, PN40, PN63, PN100, and PN160. The nominal pressure ratings for the Class series are designated by "Class" and comprise the following six levels: Class150, Class300, Class600, Class900, Class1500, and Class2500. Flange Classification 1. **According to Chemical Industry Standards:** Flanges are classified as follows: Plate Flat Welding Flange (PL), Necked Flat Welding Flange (SO), Necked Butt Welding Flange (WN), Integral Flange (IF), Socket Welding Flange (SW), Threaded Flange (Th), Butt Welding Ring Loose Flange (PJ/SE), Blind Flange (BL), Flat Welding Ring Loose Flange (PJ/PJ), and Lined Blind Flange (BL(s)). 2. **According to Petrochemical (SH) Industry Standards:** Flanges are classified as follows: Threaded Flange (PL), Butt Welding Flange (WN), Flat Welding Flange (SO), Socket Welding Flange (SW), Loose Flange (LJ), and Blind Flange (no specific designation). 3. **According to Machinery (JB) Industry Standards:** Flanges are classified as follows: Integral Flange, Butt Welding Flange, Plate Flat Welding Flange, Butt Welding Ring Plate Loose Flange, Flat Welding Ring Plate Loose Flange, Lap Joint Ring Plate Loose Flange, and Blind Flange. 4. **According to Connection Method/Type:** Flanges are classified as follows: Plate Flat Welding Flange, Necked Flat Welding Flange, Necked Butt Welding Flange, Socket Welding Flange, Threaded Flange, Blind Flange, Necked Butt Welding Ring Loose Flange, Flat Welding Ring Loose Flange, Ring-Type Joint (RTJ) Flange and Blind Flange, Large-Diameter Plate Flange, Large-Diameter High-Neck Flange, Figure-8 Blind Plate, Butt Welding Ring Loose Flange, etc. 5. **According to the Component Being Connected:** Flanges can be classified into Vessel Flanges and Pipe Flanges. 6. **According to Structural Type:** Flanges include Integral Flanges, Threaded Flanges, Flat Welding Flanges, Butt Welding Flanges, Lap Joint (Loose/Swivel) Flanges, and Blind Flanges. A flange—also referred to as a flange plate or rim—is a component used to connect shafts to one another, or, more commonly, to join the ends of pipes. Flanges are also utilized at the inlet and outlet ports of equipment to facilitate connections between two devices—for instance, the flange on a speed reducer. A "flange connection" or "flanged joint" refers to a detachable joint assembly comprising three interconnected elements—a flange, a gasket, and bolts—that together form a sealed structural unit. In the context of piping systems, a "pipe flange" specifically denotes a flange used for plumbing within the installation; when applied to equipment, it refers to the inlet or outlet flange of that specific device. Flanges feature a series of holes through which bolts are inserted to securely fasten the two flanges together, while a gasket placed between the flanges ensures a leak-proof seal. Flanges are broadly categorized into three types: threaded (screw-in) flanges, welded flanges, and clamp-type flanges. Flanges are invariably used in pairs; threaded flanges are suitable for low-pressure piping applications, whereas welded flanges are required for systems operating at pressures exceeding 4 kilograms per square centimeter. A sealing gasket is inserted between the two flange plates, which are then firmly secured using bolts. The thickness of a flange—as well as the specifications of the bolts used to fasten it—vary depending on the specific pressure rating required for the application. When connecting equipment such as water pumps or valves to piping systems, the corresponding connection points on these devices are often manufactured in the shape of a matching flange; this method of attachment is also referred to as a "flange connection." Generally, any connecting component that utilizes bolts to join and seal the perimeters of two flat surfaces—such as the joints in ventilation ducts—is termed a "flange"; such components may collectively be classified as "flange-type parts." However, since such a connection often constitutes merely a *portion* of a larger device—for instance, the interface between a flange and a water pump—it would be inappropriate to classify the entire water pump itself as a "flange-type part." Conversely, smaller components—such as valves—that feature such flanged interfaces may indeed be appropriately categorized as "flange-type parts." -:- For detailed product information, please contact sales. -: AISI 4340 Steel Flange, annealed, 25 mm round Product Information -:- For detailed product information, please contact sales. -: AISI 4340 Steel Flange, annealed, 25 mm round Synonyms -:- For detailed product information, please contact sales. -:

AISI 4340 Steel, annealed, 25 mm round Product Information -:- For detailed product information, please contact sales. -: # **AISI 4340 Steel - Annealed Product Specification** ## **1. Product Overview & Classification** **AISI 4340** is a premier **nickel-chromium-molybdenum alloy steel** renowned for its exceptional combination of high strength, toughness, and fatigue resistance. Often referred to as the "workhorse" of high-performance alloy steels, 4340 provides an optimal balance of properties that make it suitable for the most demanding applications in aerospace, defense, and heavy industry. Supplied in the annealed condition, this material offers excellent machinability and serves as an ideal starting point for subsequent heat treatment. **Material Classification:** - **Series:** 43xx Nickel-Chromium-Molybdenum alloy steel - **Carbon Level:** Medium (0.38-0.43%) - optimized for strength and hardenability - **Nickel Content:** High (1.65-2.00%) for superior toughness - **Primary Attributes:** Exceptional strength-to-toughness ratio, excellent hardenability, superior fatigue resistance - **Condition:** Fully annealed to maximize machinability - **Form:** 25 mm (1 inch) diameter round bar - ideal for many applications **Key Advantages:** - **Proven Performance:** Decades of successful use in critical applications - **Versatility:** Suitable for various heat treatment processes - **Reliability:** Consistent, predictable material behavior - **Availability:** Widely produced and readily available ## **2. International Standards & Designations** | Region/Standard | Designation | Equivalent Standard | Notes | |-----------------|-------------|---------------------|-------| | **United States** | AISI 4340, SAE 4340, UNS G43400 | ASTM A29/A29M, SAE J404, J412 | Standard annealed condition | | **UNS System** | G43400 | Unified Numbering System | Official UNS designation | | **Europe** | 1.6562 (34CrNiMo6) | EN 10083-3 | Close equivalent | | **Japan** | SNCM439 | JIS G4103 | Standard equivalent | | **China** | 40CrNiMoA | GB/T 3077 | National standard | | **ISO** | 34CrNiMo6 | ISO 683-18 | International standard | | **Aerospace** | AMS 6414, AMS 6415 | Aerospace Material Specifications | Heat treated versions | | **Common Industry** | Often called "4340 Annealed" or "4340-A" | Various manufacturer standards | | **Note:** 25 mm (1 inch) diameter is one of the most commonly stocked sizes for this material. ## **3. Chemical Composition (Weight %)** *Precisely balanced for optimal performance* | Element | Composition Range (%) | Typical Aim (%) | Metallurgical Function | |---------|----------------------|-----------------|------------------------| | **Carbon (C)** | 0.38 - 0.43 | 0.40 | Primary strengthener; provides optimum hardenability and strength | | **Manganese (Mn)** | 0.60 - 0.80 | 0.70 | Enhances hardenability and strength | | **Phosphorus (P)** | ≤ 0.035 | 0.020 | Controlled low level for maximum toughness | | **Sulfur (S)** | ≤ 0.040 | 0.025 | Improves machinability; forms MnS inclusions | | **Silicon (Si)** | 0.15 - 0.35 | 0.25 | Deoxidizer; solid solution strengthener | | **Nickel (Ni)** | 1.65 - 2.00 | 1.82 | **Critical element:** Dramatically improves toughness and impact resistance | | **Chromium (Cr)** | 0.70 - 0.90 | 0.80 | Enhances hardenability; improves wear resistance | | **Molybdenum (Mo)** | 0.20 - 0.30 | 0.25 | Improves hardenability; prevents temper embrittlement | **Special Composition Characteristics:** - **Carbon-Nickel Synergy:** Provides optimal strength-toughness combination - **Molybdenum Benefit:** Essential for preventing 475°C (885°F) embrittlement - **Balanced Alloying:** Each element contributes to specific properties - **Consistency:** Tightly controlled composition for predictable performance **Quality Enhancements (Often Specified):** - **Vacuum Degassing:** For improved cleanliness and reduced gas content - **Fine Grain Practice:** Aluminum treated for ASTM 5-8 grain size - **Inclusion Control:** ASTM E45 ratings typically specified - **Trace Element Control:** Sn, As, Sb limited for temper embrittlement resistance ## **4. Hardenability Characteristics** *Exceptional hardenability - a defining feature of 4340* ### **Jominy End-Quench Data (Base Material)** | Distance from Quenched End | As-Quenched Hardness (HRC) | After Tempering (540°C/1000°F) | |----------------------------|----------------------------|--------------------------------| | **J₁ (Surface)** | 55 - 59 | 35 - 39 | | **J₄ (1/4" depth)** | 52 - 56 | 34 - 38 | | **J₈ (1/2" depth)** | 48 - 52 | 33 - 37 | | **J₁₂ (3/4" depth)** | 44 - 48 | 32 - 36 | | **Center of 25 mm bar** | ~50 HRC | ~34 HRC | **Hardenability Performance Metrics:** - **Ideal Critical Diameter (Dᵢ):** 125-150 mm (5-6 inches) in oil - **95% Martensite Diameter (D₉₅):** 100-125 mm (4-5 inches) in oil - **Grossmann Hardenability Factor:** 5.5-6.5 (Exceptional) - **Maximum Section for Full Hardening:** 175 mm (7 inches) with proper quench - **For 25 mm diameter:** 100% martensite easily achievable with oil quench ## **5. Physical Properties (Annealed Condition)** | Property | Value | Conditions/Notes | |----------|-------|------------------| | **Density** | 7.85 g/cm³ (0.284 lb/in³) | At 20°C | | **Melting Range** | 1415-1505°C (2580-2740°F) | - | | **Modulus of Elasticity (E)** | 205 GPa (29.7 × 10⁶ psi) | At 20°C | | **Shear Modulus (G)** | 80 GPa (11.6 × 10⁶ psi) | At 20°C | | **Poisson's Ratio (ν)** | 0.29 | At 20°C | | **Thermal Conductivity** | 41.0 W/m·K | At 100°C | | **Specific Heat Capacity** | 475 J/kg·K | At 20°C | | **Coefficient of Thermal Expansion** | 12.1 × 10⁻⁶ /K | 20-100°C range | | **Electrical Resistivity** | 0.23 µΩ·m | At 20°C | | **Magnetic Properties** | Ferromagnetic | Below Curie temperature (~770°C) | | **Thermal Diffusivity** | 11.2 × 10⁻⁶ m²/s | At 20°C | ## **6. Mechanical Properties (Annealed Condition)** *Minimum guaranteed properties for 25 mm diameter after proper annealing* | Property | Minimum Value | Typical Value | Test Standard | |----------|---------------|---------------|---------------| | **Hardness (Brinell)** | 217 HB | 235 HB | ASTM E10 | | **Hardness (Rockwell)** | 95 HRB | 100 HRB | ASTM E18 | | **Tensile Strength** | 745 MPa (108 ksi) | 825 MPa (120 ksi) | ASTM A370 | | **Yield Strength (0.2%)** | 470 MPa (68 ksi) | 550 MPa (80 ksi) | ASTM A370 | | **Elongation in 50 mm** | 22% | 25% | ASTM A370 | | **Reduction of Area** | 50% | 55% | ASTM A370 | | **Charpy V-Notch Impact (20°C)** | 54 J (40 ft-lb) | 81 J (60 ft-lb) | ASTM A370 | | **Charpy V-Notch Impact (-40°C)** | 34 J (25 ft-lb) | 54 J (40 ft-lb) | ASTM A370 | | **Fatigue Strength (10⁷ cycles)** | 380 MPa (55 ksi) | 450 MPa (65 ksi) | ASTM E466 | | **Machinability Rating** | 55% of B1112 | - | Industry standard | **Benefits of Annealed Condition for 25 mm Diameter:** - **Optimal Machinability:** Maximum softness for efficient machining - **Dimensional Stability:** Minimal residual stress reduces distortion during machining - **Uniform Properties:** Consistent throughout cross-section - **Predictable Behavior:** Known starting point for heat treatment ## **7. Annealing Process Details** ### **Standard Annealing Practice for 4340** ``` Annealing Temperature: 830-860°C (1525-1580°F) Typical Cycle: 1. Heat slowly to 650°C (1200°F) to prevent thermal shock 2. Heat to annealing temperature: 845°C ±10°C (1555°F ±20°F) 3. Soak time: 45-60 minutes for 25 mm diameter 4. Cool: Furnace cool at ≤15°C/hour (27°F/hour) to 600°C (1110°F) 5. Final cooling: Air cool to room temperature 6. Result: Hardness typically 217-255 HB Alternative: Spheroidize Annealing Temperature: 740-760°C (1365-1400°F) Time: Extended (4-8 hours) Cooling: Very slow (≤5°C/hour to 600°C) Result: Optimal machinability (hardness ~197-229 HB) ``` ### **Metallurgical Result of Proper Annealing** - **Microstructure:** Spheroidized carbides in ferrite matrix - **Carbide Morphology:** Well-rounded, evenly distributed carbides - **Grain Size:** ASTM 5-7 (controlled) - **Decarburization:** ≤0.38 mm (0.015 in) total depth typically - **Uniformity:** Excellent throughout 25 mm cross-section - **Surface Condition:** Typically shot blasted or pickled after annealing ### **Why Annealing is Critical for 4340:** 1. **Machinability Enhancement:** Softest possible condition for this alloy 2. **Stress Relief:** Eliminates residual stresses from previous processing 3. **Dimensional Stability:** Minimizes distortion during subsequent machining 4. **Consistent Starting Point:** Uniform microstructure for predictable heat treatment 5. **Grain Structure Control:** Produces optimal structure for final properties ## **8. Machinability & Manufacturing Characteristics** ### **Machinability in Annealed Condition** - **Relative Machinability:** 55% (compared to 100% for B1112 steel) - **Rating:** Fair to Good for an alloy steel - **Chip Formation:** Produces manageable, segmented chips - **Surface Finish:** Capable of 1.6-3.2 µm Ra with proper technique - **Tool Life:** Moderate with appropriate tool materials - **Nickel Benefit:** Less tendency for built-up edge than some alloy steels ### **Recommended Machining Parameters for 25 mm Diameter** | Operation | Speed (m/min) | Feed (mm/rev) | Tool Recommendations | Notes | |-----------|--------------|---------------|----------------------|-------| | **Turning** | 35-60 | 0.15-0.30 | C2/C6 carbide, positive rake | Use coolant | | **Drilling** | 20-30 | 0.10-0.18 | HSS-Co drills, peck drilling | For depths >3× diameter | | **Milling** | 30-50 | 0.10-0.22 | Carbide end mills | Climb milling recommended | | **Tapping** | 6-12 | - | Premium HSS-E taps | Use tapping fluid | | **Threading** | 20-35 | - | Carbide inserts | Single-point threading preferred | | **Sawing** | 25-40 | - | Bi-metal bandsaw blades | Use cutting fluid | ### **Special Machining Considerations** 1. **Work Hardening:** Moderate tendency - maintain consistent feed rates 2. **Chip Control:** Use chipbreakers for turning operations 3. **Coolant:** Highly recommended for heat dissipation and chip evacuation 4. **Tool Geometry:** Positive rake angles reduce cutting forces 5. **Rigidity:** Ensure machine and fixture rigidity for best results ## **9. Subsequent Heat Treatment Potential** ### **Quenching and Tempering (Most Common)** ``` Standard Heat Treatment for 4340: 1. Austenitize: 830-860°C (1525-1580°F) 2. Soak: 30 minutes per inch minimum 3. Quench: Oil (fast oil, 40-60°C, agitated) 4. Temper: According to desired final properties 5. Typical Results: - 205°C temper: 52-56 HRC, 1790-1930 MPa tensile - 425°C temper: 42-46 HRC, 1380-1520 MPa tensile - 540°C temper: 35-39 HRC, 1170-1310 MPa tensile - 595°C temper: 31-35 HRC, 1030-1170 MPa tensile ``` ### **Carburizing Potential** *Though primarily a through-hardening steel, 4340 can be carburized:* - **Case Depth:** Up to 1.5 mm possible - **Surface Hardness:** 58-63 HRC achievable - **Core Properties:** Maintains excellent toughness - **Applications:** Specialized components requiring both case hardness and tough core ### **Austempering & Other Treatments** - **Austempering:** Produces bainitic structure for exceptional toughness - **Nitriding:** For additional surface hardness (up to 72 HRC) - **Induction Hardening:** For localized surface hardening ## **10. Product Applications** ### **Aerospace & Defense (Primary Applications)** - **Aircraft landing gear components** (main and nose gear) - **Helicopter rotor hubs** and **components** - **Jet engine shafts** and **mounts** - **Missile body sections** and **structural members** - **Armor vehicle components** requiring ballistic protection - **Weapon system components** requiring reliability ### **Automotive & Racing** - **High-performance crankshafts** and **connecting rods** - **Racing transmission gears** and **shafts** - **Suspension components** for performance vehicles - **Drive train components** for drag racing and motorsports - **Turbocharger shafts** for high-boost applications ### **Oil & Gas Industry** - **Drill collar connections** for deep wells - **Tool joints** and **heavy-weight drill pipe** - **Downhole tool components** for extreme environments - **Valve stems** for high-pressure service - **BOP (Blowout Preventer) components** ### **Power Generation** - **Turbine shafts** for steam and gas turbines - **Generator rotor shafts** for large generators - **Large compressor shafts** for industrial applications - **Coupling hubs** for high-torque transmission - **Pump shafts** for boiler feed applications ### **Industrial Machinery** - **Extruder screws** for plastics and rubber - **Press frames** and **components** for metal forming - **Large gear blanks** for heavy machinery - **Rolling mill rolls** for steel production - **Mining equipment components** subject to impact ### **Why 25 mm Diameter is Ideal:** 1. **Common Size:** Widely available from distributors 2. **Versatility:** Suitable for many shaft and pin applications 3. **Heat Treatment:** Optimal for uniform through-hardening 4. **Machining:** Good chip control and surface finish achievable 5. **Cost-Effective:** Competitive pricing due to volume production ## **11. Comparison with Similar Grades** ### **vs. AISI 4140 (Common Alternative)** | Parameter | AISI 4340 | AISI 4140 | Advantage | |-----------|-----------|-----------|-----------| | **Nickel Content** | 1.65-2.00% | None | 4340: Superior toughness | | **Toughness at same hardness** | Much higher | Good | 4340: 50-100% better impact | | **Fatigue Strength** | Higher | Good | 4340: 15-25% better | | **Hardenability** | Excellent | Very Good | 4340: Larger sections possible | | **Cost** | Higher | Lower | 4140: More economical | | **Applications** | Critical components | General high-strength | Different performance levels | ### **vs. AISI 4330 & 4337** | Aspect | AISI 4340 | AISI 4330 | AISI 4337 | Selection Guide | |--------|-----------|-----------|-----------|----------------| | **Carbon** | 0.38-0.43% | 0.28-0.33% | 0.35-0.40% | Different strength levels | | **Strength** | Highest | Lower | Intermediate | Application dependent | | **Toughness** | Exceptional | Excellent | Excellent | All good; 4340 best | | **Primary Use** | Maximum performance | High toughness needed | Balanced properties | Different optimizations | ## **12. Quality Assurance & Testing** ### **Standard Testing Package** 1. **Chemical Analysis:** Full spectrographic analysis (OES preferred) 2. **Hardness Testing:** Brinell or Rockwell, multiple locations 3. **Tensile Testing:** Per ASTM A370 at room temperature 4. **Charpy Impact Testing:** At 20°C (optional at -40°C) 5. **Microstructure Examination:** Verification of annealed structure 6. **Grain Size Measurement:** ASTM E112 method 7. **Decarburization Check:** Depth measurement if specified ### **Enhanced Testing for Critical Applications** - **Ultrasonic Testing:** Per ASTM A388 for internal soundness - **Magnetic Particle Inspection:** Per ASTM A275/A966 for surface defects - **Macroetch Testing:** For solidification pattern and segregation - **Fracture Toughness Testing:** K₁c or J₁c testing for critical applications - **Fatigue Testing:** Rotating beam or axial testing - **Hardenability Testing:** Jominy test if certification required ### **Certification Requirements** - **Mill Test Certificate:** Standard 3.1 per EN 10204 or equivalent - **Heat Number Traceability:** Full chemistry and test results - **Process Certificates:** Annealing cycle documentation if critical - **Third-Party Inspection:** Available if specified ## **13. Design & Engineering Considerations** ### **Design Advantages of 4340** 1. **High Strength-to-Weight Ratio:** Excellent for weight-critical applications 2. **Superior Fatigue Resistance:** Ideal for cyclic loading applications 3. **Good Fracture Toughness:** Resists crack propagation 4. **Wide Hardness Range:** Can be heat treated from 30-55 HRC as needed 5. **Proven Reliability:** Decades of successful use in critical applications ### **Design Recommendations** - **Fillet Radii:** Minimum 3 mm (0.125 in) on internal corners - **Surface Finish:** Critical areas should be ≤1.6 µm Ra before heat treatment - **Stress Concentrations:** Avoid sharp transitions; use generous radii - **Corrosion Protection:** Essential - material has no inherent corrosion resistance - **Joining Methods:** Can be welded with proper procedures (pre/post heat treatment) ### **Temperature Limitations** - **Maximum Service Temperature:** 425°C (800°F) continuous - **Short-term Exposure:** Up to 480°C (900°F) acceptable - **Low Temperature Service:** Excellent down to -40°C (-40°F) - **Temper Embrittlement Range:** 375-575°C (700-1070°F) - avoid prolonged exposure ## **14. Economic & Supply Considerations** ### **Market Availability** - **Production Status:** Widely produced by multiple mills worldwide - **Lead Times:** Typically 2-6 weeks for annealed condition - **Minimum Orders:** 500-1000 kg typically from distributors - **Cost Factor:** 2.0-2.5× AISI 1020 cost - **Stock Availability:** 25 mm diameter commonly in stock at steel service centers ### **Cost Comparison with Alternatives** | Material | Relative Cost | Performance Level | Best Application | |----------|---------------|------------------|-----------------| | **AISI 4140** | 1.0× | Very Good | General high-strength | | **AISI 4340** | 1.4× | Excellent | Critical applications | | **300M (4340M)** | 2.0× | Premium | Aerospace primary structures | | **Aerospace Titanium** | 5.0×+ | Specialized | Weight-critical applications | ### **Total Cost of Ownership Benefits** 1. **Extended Service Life:** Superior properties reduce replacement frequency 2. **Reduced Maintenance:** Better fatigue resistance means fewer failures 3. **Weight Savings:** Higher strength allows lighter designs 4. **Reliability:** Proven performance reduces warranty claims 5. **Versatility:** One material for multiple applications simplifies inventory ## **15. Technical Specifications Summary** ### **Material Selection Guidelines** ``` Decision Tree for 4340 Selection: Start: Need high strength with exceptional toughness │ ├─→ If maximum toughness at high strength needed → 4340 excellent │ ├─→ If cost is primary constraint → Consider 4140 │ ├─→ If welding required frequently → Consider lower carbon grade │ ├─→ If corrosion resistance needed → Not suitable (consider stainless) │ ├─→ If very large sections (>150 mm) → 4340 excellent │ └─→ If weight is critical → 4340 good (better options exist) ``` ### **25 mm Diameter Specific Advantages** 1. **Heat Treatment:** Ideal size for uniform through-hardening 2. **Availability:** Most common size with best pricing 3. **Versatility:** Suitable for wide range of applications 4. **Machining:** Good chip control and surface finish achievable 5. **Testing:** Representative properties for design calculations ### **Implementation Recommendations** 1. **Supplier Selection:** Choose reputable mills or distributors 2. **Quality Verification:** Conduct incoming inspection for critical applications 3. **Heat Treatment Planning:** Partner with qualified heat treaters 4. **Design Optimization:** Leverage material properties in design 5. **Life Cycle Planning:** Consider total cost, not just material cost --- ## **Technical Appendix: Calculations & Predictions** ### **Empirical Relationships for Annealed 4340** 1. **Tensile Strength (MPa) ≈ 3.5 × HB** *Example: 235 HB → 3.5 × 235 = 822 MPa* 2. **Yield Strength ≈ 0.66 × Tensile Strength** (annealed condition) *Example: 822 MPa × 0.66 = 543 MPa* 3. **Fatigue Ratio (σₑ/UTS):** 0.50-0.55 for polished specimens 4. **Impact Transition Temperature:** Typically below -40°C ### **Heat Treatment Response Predictions for 25 mm Diameter** ``` After Oil Quench and Temper: Tempering Temperature → Hardness → Tensile Strength 205°C (400°F) → 52-56 HRC → 1790-1930 MPa 425°C (800°F) → 42-46 HRC → 1380-1520 MPa 540°C (1000°F) → 35-39 HRC → 1170-1310 MPa 595°C (1100°F) → 31-35 HRC → 1030-1170 MPa Impact Toughness: Increases with tempering temperature Fatigue Strength: Optimal at 425-540°C tempering range ``` --- ## **Summary: Application Guidelines** ### **When AISI 4340 Annealed is the Right Choice:** 1. **Critical Components:** Where failure has severe consequences 2. **High-Stress Applications:** Requiring both strength and toughness 3. **Fatigue-Critical Parts:** Subject to cyclic loading 4. **Large Sections:** Requiring through-hardening 5. **Proven Performance Needed:** For applications with established 4340 use ### **Considerations for Implementation:** - **Heat Treatment:** Essential for achieving desired properties - **Machining:** Best done in annealed condition - **Quality Control:** Important for critical applications - **Cost Justification:** Based on performance requirements - **Supply Chain:** Ensure reliable source for consistent quality ### **Value Proposition:** AISI 4340 in annealed 25 mm diameter provides: - **Proven performance** in demanding applications - **Excellent starting condition** for subsequent heat treatment - **Good machinability** for complex components - **Wide availability** and competitive pricing - **Versatility** for various high-performance applications --- **Final Recommendation:** AISI 4340 annealed 25 mm round represents one of the most versatile and reliable high-performance alloy steels available. Its combination of properties, proven track record, and wide availability make it an excellent choice for critical components across multiple industries. When properly heat treated, it delivers performance that justifies its premium over more common alloy steels. **Industry Perspective:** For over 70 years, AISI 4340 has set the standard for high-strength, high-toughness alloy steels. Its continued widespread use across aerospace, defense, and industrial applications testifies to its exceptional combination of properties and reliability. --- **Disclaimer:** This product specification is for technical reference. Actual properties may vary based on specific manufacturing processes, annealing parameters, and testing methods. For critical applications, always verify material certifications, conduct incoming inspection, and perform appropriate qualification testing. Always consult with materials engineering specialists for safety-critical applications. The information presented represents typical values but should not be used as the sole basis for design decisions. -:- For detailed product information, please contact sales. -: AISI 4340 Steel, annealed, 25 mm round Specification Dimensions Size： Diameter 20-1000 mm Length <4064 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 4340 Steel, annealed, 25 mm round Properties -:- For detailed product information, please contact sales. -:

Applications of AISI 4340 Steel Flange, annealed, 25 mm round -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI 4340 Steel Flange, annealed, 25 mm round -:- For detailed product information, please contact sales. -:

Packing of AISI 4340 Steel Flange, annealed, 25 mm round -:- 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 Flange 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 535 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