AISI 4615 Steel Rod/Bar

AISI 4615 Steel Rod Product Information -:- For detailed product information, please contact sales. -: AISI 4615 Steel Rod Synonyms -:- For detailed product information, please contact sales. -:

AISI 4615 Steel Product Information -:- For detailed product information, please contact sales. -: # **Technical Specification: AISI 4615 Nickel-Molybdenum Alloy Steel** ## **1. PRODUCT OVERVIEW** AISI 4615 is a low-carbon, nickel-molybdenum alloy steel specifically designed for **case hardening applications**, particularly **carburizing and carbonitriding**. Characterized by its **exceptional core toughness and good hardenability**, this steel combines moderate nickel content (1.65-2.00%) with molybdenum (0.20-0.30%) to produce components with a hard, wear-resistant surface and a remarkably tough, strong core. The nickel content significantly enhances toughness and impact resistance, even at low temperatures, making AISI 4615 a premium choice for safety-critical, high-stress components subjected to dynamic loading and fatigue, such as gears, shafts, and fasteners in demanding industries like aerospace, automotive, and heavy machinery. --- ## **2. MATERIAL SPECIFICATIONS & STANDARDS** | **Parameter** | **Specification** | **Governing Standards** | |---------------|-------------------|-------------------------| | **Material Designation** | AISI 4615 / SAE 4615 | SAE J404, SAE J412 | | **UNS Number** | G46150 | ASTM A29 | | **International Equivalents** | DIN 1.6523 (similar), 15NiCrMo13-6 | ISO 683-11:2016 | | **Common Forms** | Bar, Wire, Forging Stock, Billets | ASTM A29/A29M, ASTM A322 | | **Typical Heat Treatment** | Case Hardening (Carburizing) | AMS 2759/7, ASTM A914 | | **Hardenability** | Good (Deep Hardening) | — | --- ## **3. CHEMICAL COMPOSITION** | **Element** | **Minimum (%)** | **Maximum (%)** | **Typical (%)** | **Metallurgical Function** | |-------------|-----------------|-----------------|-----------------|---------------------------| | **Carbon (C)** | 0.13 | 0.18 | 0.15 | Provides core strength, base for case carbon enrichment. | | **Manganese (Mn)** | 0.45 | 0.65 | 0.55 | Increases hardenability, aids in deoxidation. | | **Phosphorus (P)** | — | 0.035 | 0.015 | Residual element (impurity, controlled). | | **Sulfur (S)** | — | 0.040 | 0.025 | Residual element (impurity, can aid machinability). | | **Silicon (Si)** | 0.15 | 0.35 | 0.25 | Deoxidizer, provides solid solution strengthening. | | **Nickel (Ni)** | 1.65 | 2.00 | 1.80 | **Primary toughening agent.** Enhances core toughness, impact strength (especially at low temperatures), and hardenability. | | **Molybdenum (Mo)** | 0.20 | 0.30 | 0.25 | Increases hardenability, refines grain structure, improves strength at elevated temperatures, reduces temper embrittlement. | | **Iron (Fe)** | Balance | Balance | Balance | Matrix element. | **Key Characteristics:** * **Carbon Equivalent (CE):** ~0.40-0.45 (Good weldability with precautions). * **Nickel Advantage:** The 1.8% Ni content is the defining feature, providing superior fracture toughness compared to standard Cr-Mo case-hardening steels. * **Hardenability:** The combination of Ni and Mo provides good depth of hardening, suitable for moderately sized sections. --- ## **4. HEAT TREATMENT & RESULTANT PROPERTIES** ### **4.1 Standard Processing: Carburizing** AISI 4615 is almost exclusively used in a **case-hardened** condition. **Typical Carburizing Cycle:** 1. **Carburize:** 900-925°C (1650-1700°F) in carbon-rich atmosphere to achieve desired case depth (e.g., 0.5-1.5 mm). 2. **Quench:** Direct quench from carburizing temperature or reheat and quench in oil. 3. **Temper:** 150-200°C (300-400°F) to relieve stresses while maintaining high hardness. 4. **(Optional) Sub-zero Treatment:** To transform retained austenite for maximum dimensional stability and hardness. ### **4.2 Final Properties After Case Hardening** | **Property** | **Case (Surface)** | **Core** | **Notes** | |--------------|--------------------|----------|-----------| | **Hardness** | 58-63 HRC (700-800 HV) | 30-40 HRC | Core hardness depends on section size and quench severity. | | **Microstructure** | High-carbon martensite + carbides + retained austenite. | Low-carbon martensite or bainite. | Nickel refines the core microstructure. | | **Ultimate Tensile Strength** | — | 900-1200 MPa (130-175 ksi) | Core strength. | | **Yield Strength (Core)** | — | 700-1000 MPa (100-145 ksi) | | | **Core Toughness (Charpy V-Notch)** | — | **50-80 J at 20°C** | **Exceptional value due to nickel.** Significantly higher than Cr-Mo grades like 4320. | ### **4.3 Physical Properties (Annealed Condition)** | **Property** | **Value** | **Unit** | |--------------|-----------|----------| | Density | 7.85 | g/cm³ | | Modulus of Elasticity | 205 | GPa | | Poisson's Ratio | 0.29 | — | | Thermal Conductivity (100°C) | ~45 | W/m·K | | Coefficient of Thermal Expansion (20-100°C) | ~12 x 10⁻⁶ | /K | --- ## **5. MECHANICAL PROPERTIES (PRE-HARDENED CONDITIONS)** *Properties vary widely with heat treatment. Below are typical ranges for common conditions.* | **Condition** | **Hardness** | **Tensile Strength** | **Yield Strength** | **Elongation** | **Key Application** | |---------------|--------------|----------------------|--------------------|----------------|---------------------| | **Annealed** | 149-179 HB | 500-600 MPa | 350-450 MPa | 25-30% | Machining stock. | | **Normalized** | 179-217 HB | 550-700 MPa | 400-550 MPa | 20-25% | Forging or pre-machining. | | **Through-Hardened & Tempered** | 35-45 HRC | 1150-1400 MPa | 1000-1200 MPa | 12-16% | For applications not requiring a hard case. | | **Case-Hardened (Core)** | 30-40 HRC | 900-1200 MPa | 700-1000 MPa | 10-15% | **Primary use state.** | --- ## **6. APPLICATIONS** AISI 4615 is selected for applications where **high surface wear resistance must be combined with exceptional core toughness and fatigue strength** to withstand shock and impact loads. ### **6.1 Primary Industries & Components** | **Industry** | **Specific Components** | **Reason for Selection** | |--------------|-------------------------|--------------------------| | **Aerospace** | Landing gear components, actuator gears, high-strength fasteners, engine accessory drive gears. | Premium toughness, fatigue resistance, and reliability for safety-critical parts. | | **Automotive (High-Performance)** | Transmission gears (esp. synchro hubs), differential gears, high-stress shafts, racing components. | Ability to handle high torque and shock loads without core failure. | | **Heavy Equipment & Mining** | Large gearbox pinions, track rollers, final drive gears, excavator bucket pins. | Superior impact resistance in harsh, high-load environments. | | **Oil & Gas** | Downhole tool components, valve parts, drilling equipment gears. | Good performance under high stress and in potentially low-temperature environments. | | **Power Transmission** | High-speed, high-load gears in industrial gearboxes, turbine drives. | Excellent bending and contact fatigue resistance. | ### **6.2 Advantages over Other Case-Hardening Steels** * **vs. 8620:** Superior core toughness and low-temperature impact properties due to higher nickel. * **vs. 4320/4320H:** Better hardenability and toughness from Mo addition, more consistent performance. * **vs. 9310:** More cost-effective while still offering excellent toughness, though not as extreme as 9310's nickel-chrome combination. --- ## **7. PROCESSING CHARACTERISTICS** ### **7.1 Machinability (Annealed/Normalized Condition)** * **Rating:** Good (~65% of 1212 steel free-machining standard). * **Recommendations:** Use standard tool steels (HSS or carbide). The nickel content can cause work hardening; use positive rake angles and sharp tools. ### **7.2 Weldability** * **Rating:** Fair to Good (with proper procedure). * **Carbon Equivalent (IIW):** ~0.45. Preheating (150-200°C) is recommended for heavier sections to avoid hydrogen-induced cracking in the heat-affected zone (HAZ). Post-weld heat treatment is advisable for critical components. ### **7.3 Forgeability** * **Rating:** Good. * **Forging Temperature Range:** 1150-900°C (2100-1650°F). Reheating may be required for large reductions. --- ## **8. INTERNATIONAL STANDARDS & EQUIVALENTS** | **Standard** | **Designation** | **Notes** | |--------------|-----------------|-----------| | **SAE (USA)** | 4615 | Standard grade. | | **ASTM (USA)** | A322 (Grade 4615) | Standard specification for steel bars, alloy. | | **UNS (USA)** | G46150 | Unified numbering system. | | **DIN (Germany)** | 1.6523 / 15NiCrMo13-6 | **Not an exact equivalent** (higher Cr). The closest common German spec for a Ni-Cr-Mo case-hardening steel. | | **ISO** | ISO 683-11:2016 | Designation for case-hardening steels. Specific ISO number varies by country. | | **JIS (Japan)** | SNCM220 | Similar Ni-Cr-Mo steel, a common equivalent. | | **GB (China)** | 15NiCrMo | General equivalent designation. | **Important Note:** While chemical compositions may be similar, exact equivalents across standards often have subtle variations in ranges. Critical applications require specification to a single standard system. --- ## **9. QUALITY ASSURANCE & TESTING** Standard mill testing for bar products typically includes: * **Chemical Analysis:** Ladle and/or product analysis. * **Hardness Testing:** Brinell or Rockwell. * **Macroetch/Microcleanliness:** Per ASTM E45 or equivalent. * **Hardenability (Jominy Test):** Can be specified (for "H" grade versions, e.g., 4615H per SAE J1268). For finished, case-hardened components: * **Case Depth Measurement:** Microhardness traverse per ISO 2639 or ASTM E1077. * **Surface & Core Hardness.** * **Microstructure Evaluation:** Case and core structure, carbide morphology, retained austenite %. --- ## **10. SUMMARY & SELECTION GUIDELINES** **Choose AISI 4615 when:** 1. The application requires **case hardening** (carburizing). 2. **Exceptional core toughness and impact resistance** are critical to prevent catastrophic failure under shock or overload conditions. 3. Components are subject to **high bending and contact fatigue stresses** (e.g., gears). 4. Performance in **low-temperature environments** is a factor. 5. A balance of performance and cost is needed, stepping above 8620/4320 but where the premium for 9310 is not justified. **Consider alternatives when:** * Only surface wear resistance is needed with minimal core stress (a cheaper grade like 1018/1020 carburized may suffice). * Maximum possible core toughness is required regardless of cost (upgrade to **AISI 9310**). * Through-hardening only is required (consider medium-carbon alloys like **4140** or **4340**). --- **Disclaimer:** The information provided is typical and for reference purposes. Specific properties are highly dependent on section size, heat treatment parameters, and manufacturing processes. For critical applications, consultation with a metallurgist and comprehensive testing of production parts under simulated service conditions are essential. -:- For detailed product information, please contact sales. -: AISI 4615 Steel Specification Dimensions Size： Diameter 20-1000 mm Length <5635 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 4615 Steel Properties -:- For detailed product information, please contact sales. -:

Applications of AISI 4615 Steel Rod -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI 4615 Steel Rod -:- For detailed product information, please contact sales. -:

Packing of AISI 4615 Steel Rod -:- 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 Rod 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 2106 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