Si vous travaillez dans des secteurs comme l'automobile, aérospatial, ou machinerie lourde, tu as besoin d'un acier qui équilibre un dur, wear-resistant surface with a tough core.EN 18NiCrMo14-6 case hardening steel—a European-standard alloy rich in nickel, chrome, et du molybdène – offre exactement cela. Ce guide détaille ses principales propriétés, applications du monde réel, processus de fabrication, et comment il se compare à d'autres matériaux, helping you choose the right steel for high-stress, wear-prone parts.
1. Material Properties of EN 18NiCrMo14-6 Case Hardening Steel
EN 18NiCrMo14-6’s unique alloy composition (especially high nickel and molybdenum) makes it ideal for case hardening. Let’s explore its properties in detail.
1.1 Composition chimique
EN 18NiCrMo14-6 follows strict European standards (DANS 10084), ensuring consistent performance for case hardening. Vous trouverez ci-dessous sa composition chimique typique:
| Élément | Symbole | Gamme de contenu (%) | Key Role |
|---|---|---|---|
| Carbone (C) | C | 0.15 – 0.21 | Low enough for ductile core; reacts with carburizing to form hard surface |
| Nickel (Dans) | Dans | 3.00 – 3.50 | Boosts core toughness and fatigue resistance |
| Chrome (Cr) | Cr | 1.40 – 1.70 | Improves hardenability and surface wear resistance |
| Molybdène (Mo) | Mo | 0.45 – 0.55 | Enhances high-temperature strength and prevents temper brittleness |
| Manganèse (Mn) | Mn | 0.50 – 0.80 | Increases workability and tensile strength |
| Silicium (Et) | Et | 0.15 – 0.35 | Aide à la désoxydation pendant la fabrication de l'acier |
| Soufre (S) | S | ≤ 0.035 | Controlled to avoid brittleness |
| Phosphore (P.) | P. | ≤ 0.035 | Minimized to prevent cracking |
| Cuivre (Cu) | Cu | ≤ 0.30 | Trace element with no major performance impact |
1.2 Propriétés physiques
These properties describe how EN 18NiCrMo14-6 behaves under physical conditions like temperature and magnetism:
- Densité: 7.85 g/cm³ (same as most nickel-chromium-molybdenum steels)
- Point de fusion: 1,420 – 1,460 °C (2,588 – 2,660 °F)
- Conductivité thermique: 44.0 Avec(m·K) à 20 °C (température ambiante)
- Coefficient de dilatation thermique: 11.8 × 10⁻⁶/°C (depuis 20 – 100 °C)
- Propriétés magnétiques: Ferromagnétique (attire les aimants), utile pour le tri et les contrôles non destructifs.
1.3 Propriétés mécaniques
Mechanical properties of EN 18NiCrMo14-6 depend on case hardening (carburation + trempe + trempe). Below are typical values for thesurface (case) etcœur:
| Propriété | Méthode de mesure | Surface (Cas) Valeur | Core Value |
|---|---|---|---|
| Dureté (Rockwell) | CRH | 58 – 62 CRH | 30 – 35 CRH |
| Dureté (Vickers) | HT | 550 – 600 HT | 280 – 320 HT |
| Résistance à la traction | MPa | — | ≥ 900 MPa |
| Limite d'élasticité | MPa | — | ≥ 650 MPa |
| Élongation | % (dans 50 mm) | — | ≥ 15% |
| Résistance aux chocs | J. (à 20 °C) | — | ≥ 60 J. |
| Fatigue Limit | MPa (rotating beam) | — | ≥ 450 MPa |
1.4 Autres propriétés
EN 18NiCrMo14-6’s standout properties make it perfect for case-hardened parts:
- Case Hardening Depth: Typiquement 0.8 – 2.0 mm (adjustable via carburizing time/temperature) — enough for wear-prone surfaces like gear teeth.
- Résistance à l'usure: Hard surface (from carburizing) resists abrasion, while the tough core absorbs impact.
- Résistance à la fatigue: Nickel and molybdenum improve resistance to repeated loads—critical for gears and shafts.
- Trempabilité: Excellent—can be case-hardened evenly across large or complex parts (par ex., essieux).
- Résistance à la corrosion: Modéré (better than standard carbon steels); needs coatings (comme le zingage) pour environnements humides/difficiles.
- Core Hardness: Balanced toughness (30 – 35 CRH) prevents parts from breaking under impact.
2. Applications of EN 18NiCrMo14-6 Case Hardening Steel
EN 18NiCrMo14-6’s hard surface and tough core make it ideal for parts that face both wear and impact. Here are its key uses:
- Engrenages: Le #1 application—including automotive transmission gears, industrial gearbox gears, and aerospace engine gears (where wear and torque meet).
- Arbres: Drive shafts in trucks, machines industrielles, and turbines (needing a hard outer layer to resist wear and a tough core to handle torque).
- Axles: Automotive axles (especially heavy-duty trucks) and agricultural machinery axles—absorbing impact while resisting wear.
- Pinions: Small gears in gearboxes or steering systems (relying on precise case hardening for smooth operation).
- Composants automobiles: Clutch hubs, arbres à cames, and differential parts—high-stress parts needing wear resistance.
- Machines industrielles: Conveyor drive gears, arbres de pompe, and compressor components—operating under long hours and heavy loads.
- Composants aérospatiaux: Landing gear shafts and engine accessory gears (where reliability and weight balance matter).
- Agricultural Machinery: Tractor gearboxes and harvester shafts—handling dusty, high-impact conditions.
- Mining Equipment: Crusher gears and conveyor shafts—resisting abrasion from rocks and heavy loads.
3. Manufacturing Techniques for EN 18NiCrMo14-6
Producing EN 18NiCrMo14-6 requires precise steps to achieve the perfect case-hardened finish. Voici le processus typique:
- Sidérurgie:
- Most EN 18NiCrMo14-6 is made using an Four à arc électrique (AEP) with vacuum degassing. This removes impurities and ensures precise control of alloy elements (especially nickel and molybdenum) to meet EN 10084 normes.
- Roulement:
- Après la sidérurgie, le métal est Laminé à chaud (à 1,150 – 1,250 °C) into billets, barres, or sheets. Pour pièces de précision, c'est alors Laminé à froid (température ambiante) pour améliorer la finition de surface et la précision dimensionnelle.
- Precision Forging:
- Pièces complexes (like gears or shafts) are forged into near-final shapes at high temperatures. This refines the grain structure, enhancing core toughness—critical for high-stress applications.
- Usinage (Pre-Carburizing):
- Forged parts are machined to near-final dimensions using Tournant (for cylindrical shapes like shafts) ou Fraisage (for gears). A small tolerance (0.1 – 0.2 mm) is left for post-heat treatment grinding.
- Traitement thermique (Case Hardening):
- The most critical step—creating a hard surface and tough core:
- Cémentation: Heat the part to 880 – 930 °C in a carbon-rich atmosphere (natural gas or propane) pour 4 – 12 heures. Carbon diffuses into the surface (0.8 – 2.0 mm de profondeur) to raise carbon content to 0.8 – 1.0%.
- Trempe: Rapidly cool the part in oil or high-pressure gas to harden the carbon-rich surface.
- Trempe: Réchauffer à 180 – 220 °C to reduce brittleness while maintaining surface hardness.
- The most critical step—creating a hard surface and tough core:
- Usinage (Post-Carburizing):
- Parts are Ground to final dimensions (removing the small pre-carburizing tolerance). This ensures ultra-smooth surfaces (critical for gear teeth) et des tolérances serrées (±0,005mm).
- Traitement de surface:
- Étapes facultatives pour améliorer les performances:
- Nitruration: Adds a thin, extra-hard layer (if even higher wear resistance is needed).
- Noircissement: Forms a protective oxide layer to prevent minor rust.
- Revêtement: Zinc plating or powder coating for corrosion resistance in wet environments.
- Étapes facultatives pour améliorer les performances:
- Contrôle de qualité:
- Rigorous testing ensures quality:
- Analyse chimique: Verify alloy content via spectrometry.
- Case hardening depth test: Measure surface carbon penetration (using microhardness testing).
- Test de dureté: Check surface (CRH) and core (CRH) dureté.
- Contrôles non destructifs: Ultrasonic testing for internal cracks; magnetic particle testing for surface defects.
- Dimensional inspection: Use CMMs (Machines à mesurer tridimensionnelles) pour vérifier les tolérances.
- Rigorous testing ensures quality:
4. Études de cas: EN 18NiCrMo14-6 in Action
Real-world examples show how EN 18NiCrMo14-6 solves industry challenges.
Étude de cas 1: Automotive Gear Failure Analysis
A heavy-duty truck manufacturer faced frequent gear failures in their transmission (lasting only 150,000 kilomètres). The original gears used a low-nickel case hardening steel, which had a brittle core and uneven case depth. Switching to EN 18NiCrMo14-6 gears (with controlled carburizing to 1.2 mm case depth) extended gear life to 400,000 kilomètres. This reduced warranty claims by 80% et sauvé $500,000 annuellement.
Étude de cas 2: Mining Equipment Pinion Optimization
A mining company struggled with pinion failures in their crusher (chaque 3 mois) due to abrasion and impact. They replaced the existing steel with EN 18NiCrMo14-6 pinions, paired with nitriding surface treatment. Post-commutation, pinion life increased to 12 mois, cutting maintenance downtime by 75% and replacement costs by 60%.
5. EN 18NiCrMo14-6 vs. Other Materials
How does EN 18NiCrMo14-6 compare to other case hardening steels and materials? Le tableau ci-dessous le décompose:
| Matériel | Similarities to EN 18NiCrMo14-6 | Différences clés | Idéal pour |
|---|---|---|---|
| AISI 52100 | Qualité roulement; ferromagnetic | No nickel; not case-hardened (through-hardened); brittle core | Standard bearings (not gears/shafts) |
| JIS SUJ2 | Carbon-chromium alloy; résistant à l'usure | No nickel; through-hardened; lower toughness | Japanese automotive bearings |
| GCr15 | Qualité roulement; carbon-chromium | No nickel; through-hardened; poor impact resistance | Chinese industrial bearings |
| 100Cr6 | European standard; through-hardened | No nickel; brittle core; not for case hardening | Light-duty bearings |
| EN 100CrMo7 | Chromium-molybdenum alloy; résistant à l'usure | Low nickel; through-hardened; lower core toughness | Heavy-duty bearings (not gears) |
| AISI M50 | High-temperature strength | No nickel; through-hardened; for high-speed bearings | Aerospace turbine bearings |
| Acier inoxydable (AISI 416) | Résistant à la corrosion | Lower surface hardness; plus cher; weaker core | Food processing gears (wet environments) |
| Ceramic Components (Al₂O₃) | Résistant à l'usure | Fragile (no impact resistance); very expensive | Haute précision, low-impact parts (not gears) |
| Composants en plastique (PA66) | Résistant à la corrosion | Low strength; no high-load use | Light-duty, low-speed parts (par ex., engrenages de jouets) |
Yigu Technology’s Perspective on EN 18NiCrMo14-6
Chez Yigu Technologie, EN 18NiCrMo14-6 is our top choice for clients needing case-hardened parts like gears and shafts. Its nickel-molybdenum blend delivers the perfect balance of surface wear resistance and core toughness—critical for heavy automotive and mining applications. We use precise carburizing (controlling depth to ±0.1 mm) and post-heat treatment grinding to ensure parts meet tight tolerances. For clients in harsh environments, we add nitriding or zinc plating, making EN 18NiCrMo14-6 parts last 2–3x longer than standard case hardening steels.
FAQ About EN 18NiCrMo14-6 Case Hardening Steel
- What is the ideal case hardening depth for EN 18NiCrMo14-6?
It depends on the application: 0.8 – 1.2 mm for gears (balanced wear and flexibility), 1.5 – 2.0 mm for shafts/axles (higher wear resistance), and can be adjusted via carburizing time and temperature. - Can EN 18NiCrMo14-6 be used in corrosive environments?
It has moderate corrosion resistance. For wet or chemical-rich environments (par ex., transformation marine ou alimentaire), apply zinc plating or powder coating to prevent rust and extend service life. - How does EN 18NiCrMo14-6 differ from through-hardened steels like AISI 52100?
EN 18NiCrMo14-6 is case-hardened (hard surface, tough core) for wear + résistance aux chocs, making it ideal for gears/shafts. AISI 52100 is through-hardened (uniformly hard, brittle core), better suited for bearings that don’t face heavy impact.