AISI 4118 Steel, direct quenched from pot, carburized

AISI 4118 Steel, direct quenched from pot, carburized, 150°C (300°F) temper Product Information -:- For detailed product information, please contact sales. -: AISI 4118 Steel, direct quenched from pot, carburized, 150°C (300°F) temper Synonyms -:- For detailed product information, please contact sales. -:

AISI 4118 Steel, direct quenched from pot, carburized, 150°C (300°F) temper Product Information -:- For detailed product information, please contact sales. -: # **Product Technical Data Sheet: Direct-Quenched & Carburized AISI 4118 Steel** **Product Designation:** AISI 4118 / SAE 4118 Direct-Quenched Carburized Steel **Heat Treatment:** Carburized, Direct Quenched from Pot, Tempered at 150°C (300°F) **Condition:** Case-Hardened with High Surface Hardness and Tough Core **Form:** Machined or Formed Components (Gears, Shafts, etc.) --- ### **1. Overview** This specification covers **AISI 4118 low-alloy steel subjected to an advanced thermochemical process: carburizing followed by direct quenching.** Components are first carburized in a controlled atmosphere to enrich the surface layer with carbon. They are then **directly quenched from the high-temperature carburizing pot** into oil, eliminating a separate reheating step. A final low-temperature temper at **150°C (300°F)** relieves quenching stresses while retaining maximum surface hardness. This process produces components with an **extremely hard, wear-resistant case** and a **strong, tough core**, optimized for high-stress, fatigue-resistant applications. ### **2. Chemical Composition (Weight %)** Base material conforms to AISI 4118. The surface (case) chemistry is altered via carburizing. | Element | Core Content (%) | Case Content (After Carburizing) | Role | | :--- | :--- | :--- | :--- | | **Carbon (C)** | 0.18 - 0.23 | **0.70 - 1.00** (at surface) | Core strength; creates high-hardness martensite in case. | | **Manganese (Mn)**| 0.70 - 0.90 | ~0.70 - 0.90 | Increases hardenability in core and case. | | **Silicon (Si)** | 0.15 - 0.35 | ~0.15 - 0.35 | Deoxidizer; can influence carburizing kinetics. | | **Chromium (Cr)** | 0.40 - 0.60 | ~0.40 - 0.60 | Enhances hardenability, wear resistance, and promotes carbide formation in case. | | **Molybdenum (Mo)** | 0.08 - 0.15 | ~0.08 - 0.15 | Improves hardenability (especially in core), reduces temper embrittlement. | | **Phosphorus (P)**| ≤ 0.035 | ≤ 0.035 | Impurity (controlled). | | **Sulfur (S)** | ≤ 0.040 | ≤ 0.040 | Impurity; can improve machinability in base state. | | **Iron (Fe)** | Balance | Balance | Base element. | ### **3. Typical Physical Properties (Post-Treatment)** * **Density:** ~7.85 g/cm³ * **Modulus of Elasticity:** 190 - 210 GPa * **Case Microstructure:** High-carbon tempered martensite with possible fine carbides. * **Core Microstructure:** Low-carbon tempered martensite/bainite. ### **4. Mechanical & Metallurgical Properties** *Properties are highly dependent on carburizing parameters (time, temperature, atmosphere) and section size.* #### **Surface Case Properties:** * **Surface Hardness:** **58 - 63 HRC** (Rockwell C). * **Effective Case Depth (ECD @ 550 HV):** Typically **0.5 - 1.5 mm** (0.020" - 0.060"), as specified. * **Core Hardness (beneath case):** **35 - 45 HRC**. The direct quench and low temper provide a strong, toughened core. * **Residual Surface Stresses:** High compressive stresses, significantly improving **fatigue life** and resistance to contact fatigue (pitting). #### **Core Properties (Approximate):** * **Tensile Strength:** 1000 - 1200 MPa (145 - 174 ksi) * **Yield Strength:** 800 - 1000 MPa (116 - 145 ksi) * **Ductility:** Good (moderate elongation and reduction of area) for impact absorption. ### **5. Detailed Heat Treatment Process** 1. **Carburizing:** Components are heated to **900 - 930°C (1650 - 1700°F)** in a carbon-rich atmosphere (e.g., endothermic gas + natural gas). Carbon diffuses into the surface, creating a high-carbon gradient. 2. **Direct Quenching:** Immediately after carburizing, components are **quenched directly from the carburizing pot into oil**. This efficient process minimizes grain growth, distortion, and energy use compared to a separate reheat-and-quench cycle. 3. **Tempering:** Heated to **150°C (300°F)** for 1-2 hours. This "stress-relief" temper reduces brittleness and quenching stresses **without significantly lowering hardness**. ### **6. Key Characteristics & Advantages** * **Superior Surface Properties:** Extreme wear resistance and anti-scuffing capability. * **Excellent Bending & Contact Fatigue Strength:** Due to hard case and compressive stresses. * **Good Core Toughness:** Mo and Cr provide strength and impact resistance in the core. * **Process Efficiency:** Direct quenching reduces cycle time, energy consumption, and potential for distortion. * **Good Dimensional Stability:** With proper process control, direct quenching can offer consistent results. ### **7. Common Applications** This high-performance material is specified for demanding, dynamically loaded components: * **Transmission Gears** (Automotive, Heavy Truck, Off-Highway) * **High-Performance Gearbox Components** (Pinions, Synchronizer Hubs) * **Camshafts and Crankshafts** (for high-load engines) * **Bearing Races and Rollers** (where integral design is used) * **Heavy-Duty Axle Shafts and Spider Gears** * **Industrial Drivetrain Components** subject to shock and wear. ### **8. International & Industry Standards** The base material is standardized; the "direct quenched, carburized" condition is a specified heat treatment path within many engineering standards. | Standard | Grade/Designation | Relevant Specification | | :--- | :--- | :--- | | **AISI/SAE (USA)** | 4118 | SAE J404 (Chemical), SAE J1268 (Hardenability) | | **ASTM (USA)** | A534 / A29 (for carburizing grades) | Covered under similar carburizing steel specs. | | **AMS (Aerospace)** | AMS 2300 / AMS 2301 | For premium-quality, clean steel grades used in similar processes. | | **ISO** | **ISO 6336-5 (Calculation for gears)** | Material quality **ME** (Material E - Alloy Steel, Quenched & Tempered). | | **DIN (Germany)** | 1.7139 (16MnCr5) | Often used for comparable applications. | | **Customer-Specific:** | | OEMs (e.g., automotive) often have proprietary internal specifications (e.g., Ford WSS, GM GMN) governing the exact case depth, hardness, and microcleanliness for direct-quenched 4118. | --- **Important Note:** The final performance is critically dependent on precise control of the **carburizing profile (carbon potential, time)** and **quenching parameters (oil type, agitation, temperature)**. This datasheet provides typical values; detailed specifications must be agreed upon between supplier and customer for the specific part geometry and application. -:- For detailed product information, please contact sales. -: AISI 4118 Steel, direct quenched from pot, carburized, 150°C (300°F) temper Specification Dimensions Size： Diameter 20-1000 mm Length <5568 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 4118 Steel, direct quenched from pot, carburized, 150°C (300°F) temper Properties -:- For detailed product information, please contact sales. -:

Applications of AISI 4118 Steel, direct quenched from pot, carburized, 150°C (300°F) temper -:- For detailed product information, please contact sales. -: Chemical Identifiers AISI 4118 Steel, direct quenched from pot, carburized, 150°C (300°F) temper -:- For detailed product information, please contact sales. -:

Packing of AISI 4118 Steel, direct quenched from pot, carburized, 150°C (300°F) temper -:- 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 2039 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