M50-NiL High Performance Carburizing Bearing and Gear Steel Rod/Bar

M50-NiL High Performance Carburizing Bearing and Gear Steel Rod Product Information -:- For detailed product information, please contact sales. -: M50-NiL High Performance Carburizing Bearing and Gear Steel Rod Synonyms -:- For detailed product information, please contact sales. -:

M50-NiL High Performance Carburizing Bearing and Gear Steel Product Information -:- For detailed product information, please contact sales. -: ### **Product Datasheet: M50-NiL High Performance Carburizing Bearing and Gear Steel** --- #### **1. Material Overview** **M50-NiL** is an **advanced, secondary-hardening, carburizing bearing steel** representing a significant evolution from the standard **M50 tool steel (AISI M50)**. The "NiL" designation indicates **Nickel-alloyed** and **Low-carbon** core composition. This proprietary grade, originally developed by NASA and now a premier aerospace material, is engineered to overcome the limitations of through-hardening bearing steels by providing an **exceptionally hard, wear-resistant surface case** over a **remarkably tough, fracture-resistant core**. It uniquely combines the **high-temperature hardness retention of M50 with the damage tolerance of a carburized steel**, making it the material of choice for ultra-high-performance, safety-critical applications in extreme environments. #### **2. Key Material Concept: The Hybrid Carburizing Approach** M50-NiL solves a critical engineering dilemma: achieving both maximum surface hardness for wear/pitting resistance and maximum core toughness for damage tolerance. - **Surface (Case):** The carburized case (~1.0% C) transforms into a microstructure rich in fine **M₂C and MC-type carbides** (primarily vanadium and molybdenum carbides) upon quenching and tempering. This provides **exceptional hardness (64-66 HRC), high-temperature strength, and rolling contact fatigue resistance** superior to conventional carburizing steels. - **Core:** The low-carbon (~0.15% C), nickel-alloyed (~3.0% Ni) core is designed for **maximum fracture toughness and crack arrest capability**. After heat treatment, the core achieves a very high toughness level (significantly higher than 9310 or CBS-600) while maintaining sufficient strength (~1000-1200 MPa UTS) to support the hard case. - **Secondary Hardening:** Like its parent M50, it exhibits **secondary hardening** during high-temperature tempering (480-560°C), where fine alloy carbides precipitate, allowing it to **retain high hardness at elevated operating temperatures (up to ~320°C / 600°F)** – a key advantage over standard carburizing grades. #### **3. International Standard & Cross-References** M50-NiL is a **proprietary, specification-controlled material**, not a standard AISI/SAE grade. - **Primary Specifications:** Governed by **Aerospace Material Specifications (AMS)**, primarily **AMS 6491E** (Steel, Corrosion-Resistant, Bearings, Vacuum Induction Plus Vacuum Consumable Electrode Melted, 4Cr-4.5Mo-1V-3Ni-0.10C (0.08C max) Consumable Electrode Melted, Carburized, Hardened, and Tempered). - **Manufacturing Process:** Requires **Double Vacuum Melting** (Vacuum Induction Melting + Vacuum Arc Remelting - VIM-VAR) to achieve the necessary cleanliness and homogeneity. - **Closest Functional Analogues:** There are no direct equivalents. It sits in a performance class above: - **SAE 9310:** For high-toughness gears. - **CBS-600 / Pyrowear® 675:** For high-performance carburized gears/bearings. - **Through-hardening M50:** For high-temperature bearings but with poor damage tolerance. #### **4. Chemical Composition (% by Weight, per AMS 6491)** | Element | Content Range (%) | Key Role in M50-NiL's Performance | | :--- | :--- | :--- | | **Carbon (C)** | **0.10 – 0.15 (Core) / ~1.0 (Case)** | Low core C for toughness; high case C for hardness and carbide formation. | | **Manganese (Mn)** | **0.10 – 0.35** | Low level to minimize residual austenite. | | **Silicon (Si)** | **0.10 – 0.35** | Deoxidizer; kept low. | | **Chromium (Cr)** | **3.75 – 4.25** | Provides hardenability, corrosion resistance, and forms carbides. | | **Nickel (Ni)** | **3.25 – 3.75** | **Core Toughening Agent.** The key to the material's exceptional fracture toughness and crack arrest properties. | | **Molybdenum (Mo)** | **4.00 – 4.50** | **Critical for Secondary Hardening.** Forms fine Mo₂C carbides during tempering, providing high-temperature strength and hardness. | | **Vanadium (V)** | **0.90 – 1.10** | Forms extremely hard, wear-resistant MC-type carbides (VC) in the case. | | **Sulfur (S)** | **≤ 0.005** | **Ultra-low** for supreme cleanliness and fatigue life. | | **Phosphorus (P)** | **≤ 0.012** | Ultra-low to prevent embrittlement. | #### **5. Typical Physical & Mechanical Properties** **A. Physical Properties:** - **Density:** ~7.85 g/cm³ - **Modulus of Elasticity:** ~200 GPa - **Thermal Conductivity:** Lower than standard steels due to high alloy content. **B. Achieved Properties After Carburizing & Heat Treatment:** - **Surface Case Hardness:** **64 – 66 HRC** (Maintains >60 HRC at 315°C / 600°F). - **Effective Case Depth:** Typically 0.5mm to 1.5mm (0.020" – 0.060"). - **Core Hardness:** **38 – 45 HRC** (After high-temperature tempering). - **Core Tensile Strength:** **1000 – 1250 MPa** (145 – 181 ksi) - **Core Yield Strength:** **800 – 1050 MPa** (116 – 152 ksi) - **Core Fracture Toughness (K1C):** **70 – 110 MPa√m** – **Exceptionally high for a hardened bearing/gear steel.** - **Core Charpy V-Notch Impact:** **40 – 70 J** (30 – 52 ft-lb) – Outstanding. - **Bending Fatigue & Contact Fatigue Life:** **Superior to all conventional carburizing steels.** #### **6. Processing & Heat Treatment Characteristics** - **Carburizing:** Typically performed via **Low-Pressure Carburizing (LPC)** or **Gas Carburizing** under tightly controlled conditions to achieve a steep carbon gradient and avoid grain growth. - **Austenitizing & Quenching:** High-temperature austenitizing (~1100°C / 2010°F) is required to dissolve the strong alloy carbides, followed by **high-pressure gas quenching or oil quenching**. - **Tempering:** **Multiple high-temperature tempers (e.g., 2-3 cycles at 525-550°C / 975-1020°F)** are used to achieve **secondary hardening**, transform retained austenite, develop core toughness, and stabilize dimensions. - **Sub-Zero Treatment:** Standard practice after quenching to maximize case hardness. - **Machinability (Pre-Carburize):** **Poor.** The high alloy content and anticipated hardness make it difficult to machine; requires specialized tooling and processes. - **Weldability:** **Very Poor.** Not recommended. #### **7. Primary Applications** M50-NiL is reserved for the most extreme performance and safety-critical applications: - **Aerospace Main Shaft Bearings:** **Jet engine main shaft bearings** where high DN values, operating temperatures, and catastrophic failure prevention are paramount. - **Advanced Gear Systems:** **Critical aerospace transmission and gearbox gears** (e.g., for tilt-rotor aircraft, advanced helicopters), especially where weight reduction and high power density are required. - **High-Performance Racing:** **Formula 1 and top-tier endurance racing gearbox and differential components**. - **Advanced Turbomachinery:** **Bearings and gears in high-speed auxiliary power units (APUs), gas turbines, and fuel pumps.** - **Critical Defense Systems:** **Bearings in missile systems, high-performance aircraft actuators, and rotorcraft drivetrains.** #### **8. Available Forms & Quality** - **Forms:** Supplied as **double-vacuum melted (VIM-VAR) forged or rolled bar stock, pre-machined rings, or custom forgings** in the soft-annealed condition. - **Quality:** Subject to the **most stringent aerospace quality controls**, including: - 100% macro-etch and ultrasonic inspection. - Stringent inclusion ratings (e.g., ASTM E45, MIL-STD-XXX). - Guaranteed hardenability and detailed microstructural requirements. - **Cost:** **Extremely High.** Justified only by performance requirements that cannot be met by any other material. #### **9. Performance Comparison** | Property | SAE 9310 | **M50-NiL** | Through-Hardened M50 | | :--- | :--- | :--- | :--- | | **Case Hardness (HRC)** | 58-62 | **64-66** | 60-64 (entire cross-section) | | **Core Toughness** | Excellent | **Exceptional / Best-in-Class** | Poor | | **High-Temp Hardness Retention** | Poor (softens above 200°C) | **Excellent (to 315°C+)** | Excellent (to 540°C) | | **Fatigue Life** | Very Good | **Superior** | Good (but brittle) | | **Damage Tolerance** | High | **Highest** | Very Low | | **Primary Use** | High-integrity gears. | **Extreme-environment bearings & gears.** | High-temperature bearings. | --- **Disclaimer:** M50-NiL is a **specialized, high-cost, processing-intensive aerospace-grade material**. Its successful application requires **deep metallurgical expertise and highly controlled, validated manufacturing processes** (carburizing, heat treatment, finishing). It is not a substitute for conventional engineering steels and should only be specified when its unique combination of **case hardness, core toughness, and elevated temperature performance** is absolutely required to meet design life and safety goals. All procurement and processing must be done in accordance with the governing specifications (e.g., AMS 6491) with approved suppliers. -:- For detailed product information, please contact sales. -: M50-NiL High Performance Carburizing Bearing and Gear Steel Specification Dimensions Size： Diameter 20-1000 mm Length <5201 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. -: M50-NiL High Performance Carburizing Bearing and Gear Steel Properties -:- For detailed product information, please contact sales. -:

Applications of M50-NiL High Performance Carburizing Bearing and Gear Steel Rod -:- For detailed product information, please contact sales. -: Chemical Identifiers M50-NiL High Performance Carburizing Bearing and Gear Steel Rod -:- For detailed product information, please contact sales. -:

Packing of M50-NiL High Performance Carburizing Bearing and Gear 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 1672 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