AISI 4150 Acier allié: Propriétés, Utilisations & Guide haute usure

Si vous concevez des pièces soumises à une friction constante, stress élevé, ou une usure importante, comme les engrenages industriels, courses de roulements, or automotive camshafts—you need a material that combines extremedureté, résistance à la traction, and wear resistance.AISI 4150 acier allié est la solution incontournable: comme chrome-molybdène à haute teneur en carbone (Cr-Mo) alliage, il offre une dureté et une résistance à l'usure plus élevées que les qualités à faible teneur en carbone comme l'AISI 4140, while maintaining enoughdureté for load-bearing applications. Ce guide détaille ses propriétés, utilisations réelles, processus de fabrication, and material comparisons to help you solve high-wear design challenges.

1. Material Properties of AISI 4150 Acier allié

AISI 4150’s performance hinges on its high-carbon (0.48–0.53%) and balanced Cr-Mo composition: carbon enables maximum hardness after heat treatment, chromium boostsrésistance à la corrosion et trempabilité, and molybdenum prevents brittleness while enhancinglimite de fatigue. Let’s explore its key properties in detail.

1.1 Composition chimique

AISI 4150 follows ASTM A29/A29M standards, with strict control over elements to prioritize hardness and wear resistance. Below is its typical composition:

1.2 Propriétés physiques

These traits make AISI 4150 suitable for high-wear, high-heat environments—from industrial gearboxes to automotive engines:

• Densité: 7.85 g/cm³ (same as standard steels)—simplifies weight calculations for heavy-wear parts like gear blanks
• Point de fusion: 1,415 – 1,445 °C (2,580 – 2,630 °F)—compatible with forging and quenching processes
• Conductivité thermique: 41.5 Avec(m·K) à 20 °C; 37.5 Avec(m·K) à 300 °C—ensures even heat distribution during quenching (avoids hot spots)
• Coefficient de dilatation thermique: 11.6 × 10⁻⁶/°C (20 – 100 °C)—minimizes distortion when heat-treating small, pièces précises (par ex., courses de roulements)
• Propriétés magnétiques: Ferromagnetic—enables non-destructive testing (CND) like magnetic particle inspection to detect surface cracks from wear.

1.3 Propriétés mécaniques

AISI 4150’s mechanical performance is optimized for hardness and wear resistance, with heat treatment tailored to end uses. Below are typical values:

1.4 Autres propriétés

AISI 4150’s traits solve high-wear design challenges:

• Weldability: Moderate—requires preheating to 300–350 °C (higher than AISI 4140) and post-weld heat treatment (PWHT) to avoid cracking; best for non-welded parts when possible.
• Formabilité: Limited—best forged (not bent) in the annealed condition; formes complexes (par ex., dents d'engrenage) are created via hot forging before heat treatment.
• Usinabilité: Fair in the annealed condition (22–25 HRC); heat-treated parts (58–60 HRC) require specialized tools (par ex., cubic boron nitride, CNB) pour usinage.
• Résistance à la corrosion: Moderate—resists mild rust and oil-based fluids; for wet or chemical environments, add chrome plating or nitride coating.
• Résistance à l'usure: Excellent—high hardness (58–60 HRC) and chromium content reduce metal-to-metal wear, extending part life by 2–3x vs. AISI 4140.

2. Applications of AISI 4150 Acier allié

AISI 4150’s focus on hardness and wear resistance makes it ideal for parts that endure constant friction or impact. Here are its key uses:

• Engrenages & Gear Components: Industrial gearbox gears, automotive transmission gears, and differential gears—its high hardness resists tooth wear from heavy loads.
• Roulements & Courses de roulements: Ball bearing races, roller bearing cups, and needle bearing sleeves—smooth, hard surfaces minimize friction and extend bearing life.
• Pièces automobiles: Arbres à cames, poussoirs de soupape, and piston pins—tolerate engine heat and repeated contact with other components.
• Composants mécaniques: High-wear shafts (par ex., conveyor drive shafts), rotors de pompe, and tool holders—withstand abrasion from dust, saleté, or metal particles.
• Machines industrielles: Steel mill rolls, extrusion dies, and stamping tools—resist wear from shaping metal or plastic.
• Composants aérospatiaux: Landing gear linkages and engine accessory gears (systèmes non critiques)—balances wear resistance and strength for aircraft use.

3. Manufacturing Techniques for AISI 4150 Acier allié

Producing AISI 4150 requires precision in heat treatment to maximize hardness without brittleness. Here’s the step-by-step process:

1. Sidérurgie:
   • AISI 4150 is made using an Four à arc électrique (AEP) (recycles scrap steel) ou Four à oxygène de base (BOF). Carbone (0.48–0.53%), chrome (0.80–1.10%), and molybdenum (0.15–0.25%) are added during melting to ensure uniform alloy distribution.
2. Forgeage & Roulement:
   • Most AISI 4150 parts start as Hot Forged blanks (1,150 – 1,250 °C)—forging aligns grain structure, boosting wear resistance. After forging, blanks are Laminé à chaud to rough shapes (barres, assiettes) or left as-forged for near-net-shape parts (par ex., arbres à cames).
3. Traitement thermique (Critical for Hardness):
   • Recuit: Heated to 815–845 °C, held 3–4 hours, slow-cooled to 650 °C. Softens the steel (22–25 HRC) for machining and forging.
   • Trempe: Heated to 830–860 °C (austenitizing), held 1–2 hours (plus long pour les pièces épaisses), cooled in oil (water cooling risks cracking). Hardens to 60–62 HRC.
   • Trempe: Reheated to 200–500 °C (based on needs):
     • 200 °C: Max hardness (58–60 HRC) for high-wear parts (par ex., courses de roulements).
     • 500 °C: Balanced hardness-toughness (35–38 HRC) for impact-prone parts (par ex., engrenages).
4. Usinage:
   • Annealed AISI 4150 is machined with carbide tools for turning, fraisage, ou perçage. Heat-treated parts (58–60 HRC) require CBN tools or grinding for precision. For gear teeth, hobbing is done in the annealed condition, followed by heat treatment and finish grinding.
5. Traitement de surface:
   • Placage: Chromage (résistance à l'usure) for shafts; nickelage (résistance à la corrosion) pour pièces automobiles.
   • Nitruration: Heats to 500–550 °C in ammonia gas—creates a 0.1–0.3 mm hard surface layer (65–70 HRC) without distortion, ideal for gears and bearings.
   • Cémentation: Optional—heats to 900–950 °C in carbon-rich gas to harden only the surface (core remains tough), used for parts like gear teeth.
6. Contrôle de qualité:
   • Chemical Analysis: Mass spectrometry verifies carbon, chrome, and molybdenum levels (per ASTM A29/A29M).
   • Mechanical Testing: Test de dureté (HRC/HV) and tensile tests confirm strength; wear tests (par ex., pin-on-disk) measure resistance to friction.
   • CND: Ultrasonic testing checks for internal defects; optical microscopy ensures uniform grain structure (no large grains that cause wear hot spots).

4. Études de cas: AISI 4150 in Action

Real projects show how AISI 4150 solves high-wear challenges.

Étude de cas 1: Industrial Gearbox Gears (NOUS.)

A manufacturing plant had to replace AISI 4140 gearbox gears every 18 months due to tooth wear. They switched to AISI 4150 engrenages, traité thermiquement pour 200 °C (58 CRH) and nitrided for extra wear resistance. Les nouveaux équipements ont duré 48 months—reducing maintenance costs by $60,000 annuellement. The high carbon content of AISI 4150 prevented tooth pitting, a common failure mode in 4140 engrenages.

Étude de cas 2: Automotive Camshafts (Japan)

An automaker needed camshafts that could withstand 200,000 km of engine operation without lobe wear. They used AISI 4150 arbres à cames, forged, traité thermiquement pour 300 °C (55 CRH), and nitrided. Testing showed only 0.02 mm of lobe wear after 200,000 km—half the wear of AISI 4140 arbres à cames. This improved engine reliability and reduced warranty claims by 35%.

5. AISI 4150 contre. Autres matériaux

How does AISI 4150 compare to lower-alloy steels and wear-resistant alternatives?

Yigu Technology’s Perspective on AISI 4150 Acier allié

Chez Yigu Technologie, AISI 4150 is our top choice for high-wear, load-bearing components. Its high-carbon Cr-Mo composition solves the biggest pain point for clients: getting parts that resist wear without breaking—critical for industrial gearboxes, moteurs automobiles, et machines. We supply AISI 4150 in forged blanks, barres, or plates, with custom heat treatment (200–500 °C) and surface options (nitruration, chromage). For clients upgrading from AISI 4140, AISI 4150 delivers 2–3x longer part life at a small cost premium—saving money on maintenance and replacements long-term.

FAQ About AISI 4150 Acier allié

1. Can AISI 4150 be used for parts that need both high wear resistance and impact toughness?
   Yes—temper it to 400–500 °C (38–42 HRC). This balances hardness (enough for wear resistance) et la ténacité (to absorb impact). Par exemple, gears tempered to 450 °C handle both tooth wear and occasional shock loads.
2. Is AISI 4150 harder to machine than AISI 4140?
   Yes—especially when heat-treated. Annealed AISI 4150 (22–25 HRC) machines similarly to annealed 4140, but heat-treated AISI 4150 (58–60 HRC) requires CBN tools or grinding, alors que 4140 (50–53 HRC) can use coated carbide tools.
3. What’s the maximum thickness for AISI 4150 parties?
   AISI 4150 works well for parts up to 100 mm thick—its chromium content ensures uniform hardening across sections. For thicker parts (＞100 mm), extend quenching hold time (2–3 heures) and use oil cooling to avoid core softening.