Acier résistant à l'usure NM450: Propriétés, Applications & Guide de fabrication

Si vous travaillez dans des secteurs comme l'exploitation minière, construction, ou agricole, you know how crucial durable materials are.NM450 wear resistant steel stands out as a top choice for parts that face constant friction and impact. This guide breaks down everything you need to know about NM450—from its core properties to real-world uses—so you can make informed decisions for your equipment.

1. Material Properties of NM450 Wear Resistant Steel

Understanding NM450’s properties is key to knowing why it works so well. Below is a detailed look at its chemical, physique, mécanique, and other key traits.

1.1 Composition chimique

NM450’s strength comes from its carefully balanced alloy mix. Le tableau ci-dessous montre sa composition chimique typique:

1.2 Propriétés physiques

These traits affect how NM450 performs in different environments:

• Densité: 7.85 g/cm³ (comme la plupart des aciers au carbone, making it easy to integrate into existing designs)
• Point de fusion: 1450 – 1500°C (high enough to handle high-temperature industrial processes)
• Conductivité thermique: 45 Avec(m·K) at 20°C (good heat dissipation, preventing overheating in heavy use)
• Coefficient de dilatation thermique: 13.5 × 10⁻⁶/°C (low expansion, reducing warping in temperature changes)
• Conductivité électrique: 15 S/m (low conductivity, ideal for parts near electrical components)

1.3 Propriétés mécaniques

NM450’s mechanical strength is its biggest advantage. All values meet international standards (par ex., GB/T 24186):

• Limite d'élasticité: ≥ 1000 MPa (resists permanent deformation under heavy loads)
• Résistance à la traction: ≥ 1250 MPa (handles high pulling forces without breaking)
• Dureté: 420 – 480 HBW (Brinell Hardness—hard enough to resist scratches and wear)
• Résistance aux chocs: ≥ 25 J at -40°C (tough even in cold weather, no easy cracking)
• Résistance à l'usure: 3 – 5 times higher than ordinary Q235 steel (proven in industrial wear tests)
• Élongation: ≥ 10% (flexible enough to avoid cracking during installation or impact)

1.4 Autres propriétés

• Résistance à la corrosion: Moderate—performs well in dry/moderately wet environments; use coatings for coastal or acidic areas.
• Oxidation Resistance: Resists rust at temperatures up to 600°C (suitable for high-heat applications like cement kilns).
• Weldability: Good with proper preheating (150 – 200°C) and low-hydrogen electrodes—critical for making large parts like buckets.
• Usinabilité: Requires carbide tools (due to high hardness), but still manageable for drilling or cutting with slow speeds.

2. Applications of NM450 Wear Resistant Steel

NM450’s mix of hardness and toughness makes it perfect for parts that take a beating. Voici ses utilisations les plus courantes:

• Mining Equipment: Liners for ore crushers, bandes transporteuses, and ore buckets. Par exemple, a coal mine in Australia replaced 普通 steel liners with NM450—liner life increased from 2 mois à 8 mois.
• Construction Machinery: Excavator buckets, bulldozer blades, and asphalt paver plates. A construction company in Germany used NM450 for excavator buckets; wear damage dropped by 60%, cutting maintenance costs.
• Agricultural Machinery: Plowshares, harvester blades, and grain silo liners. NM450 resists wear from soil and crop residues—farmers report 2x longer life for plowshares.
• Wear-Resistant Liners: Used in cement mixers, sand mixers, and waste treatment equipment. A concrete plant in China installed NM450 liners in mixers; liner replacement frequency fell from 3 times/year to 1 time/year.
• Grinding Balls and Rods: For mineral processing mills. NM450 grinding balls last 40% longer than cast iron balls, reducing downtime for ball replacement.
• Wear-Resistant Pipes: For transporting sand, gravel, or slurry. In a dredging project in the Netherlands, NM450 pipes lasted 5 years—compared to 2 years for standard steel pipes.

3. Manufacturing Techniques of NM450 Wear Resistant Steel

Making NM450 requires precise processes to ensure its properties. Voici une ventilation étape par étape:

1. Steelmaking Process:
   • Uses the BOF (Four à oxygène de base) or EAF (Four à arc électrique) méthode.
   • Matières premières (iron ore, scrap steel) are melted, and alloys (Mn, Cr, Nb) are added to reach the target chemical composition.
   • Strict quality control checks for P and S levels (kept below 0.03% to avoid brittleness).
2. Alloying Process:
   • Alloys are added in two stages: first during melting, then during secondary refining (LF furnace).
   • Niobium (Nb) ou Vanadium (V) is added last to refine the steel’s grain structure—this improves toughness without reducing hardness.
3. Traitement thermique:
   • Trempe: The steel is heated to 900 – 950°C, détenu pendant 1 – 2 heures, then rapidly cooled with water. This forms a hard martensite structure.
   • Trempe: After quenching, the steel is heated to 200 – 300°C pour 2 – 3 heures. This reduces internal stress and balances hardness with toughness.
4. Rolling Process:
   • Hot rolling at 1000 – 1100°C shapes the steel into plates (épaisseur 3 – 100 mm) or coils.
   • Cold rolling is sometimes used for thinner plates (≤ 3 mm) to improve surface smoothness.
5. Forging Process:
   • Used for complex parts (par ex., large crusher liners).
   • The steel is heated to 800 – 900°C and pressed into molds. Forging improves density and reduces internal defects.
6. Traitement de surface:
   • Cémentation: Heating in a carbon-rich gas (900 – 950°C) adds a hard carbon layer (0.5 – 1 mm d'épaisseur) to the surface—ideal for parts needing extra wear resistance.
   • Nitruration: Heating in ammonia gas (500 – 550°C) forms a nitrogen layer. This boosts corrosion resistance without affecting the core toughness.

4. Case Studies and Real-World Examples

Seeing NM450 in action helps prove its value. Here are two detailed case studies:

Étude de cas 1: Mining Crusher Liners in South Africa

• Problème: A gold mine used ordinary Q345 steel liners in its jaw crusher. Liners wore out every 3 mois, provoquant 8 hours of downtime per replacement.
• Solution: Switched to 20 mm thick NM450 liners.
• Résultats:
  • Liner life increased to 10 mois.
  • Temps d'arrêt réduits de 70% (depuis 32 hours/year to 9.6 hours/year).
  • Annual cost savings: $45,000 (lower liner costs + less downtime).

Étude de cas 2: Agricultural Harvester Blades in the US

• Problème: A farm equipment manufacturer used cast iron blades for corn harvesters. Blades dulled after 500 acres, requiring frequent sharpening.
• Solution: Replaced cast iron with NM450 blades (5 mm d'épaisseur).
• Résultats:
  • Blade life extended to 1,800 acres.
  • Sharpening frequency dropped from 4 times/season to 1 time/season.
  • Farmer satisfaction increased by 85% (survey of 50 utilisateurs).

5. Comparative Analysis with Other Materials

How does NM450 stack up against other wear-resistant options? Le tableau ci-dessous compare les facteurs clés:

Cost-Effectiveness Takeaway

• NM450 is more cost-effective than ceramics (3x cheaper) and lasts longer than cast iron (2-3x longer).
• For parts with both wear and impact, NM450 beats other steels (par ex., NM400) because it offers better wear resistance without losing toughness.

Yigu Technology’s Perspective on NM450 Wear Resistant Steel

Chez Yigu Technologie, we’ve supplied NM450 steel to over 200 clients in mining, construction, and agriculture. Our experience shows NM450 is a “workhorse” material—its balance of hardness and toughness solves the biggest pain point for our customers: unplanned downtime. We often recommend NM450 for custom parts (par ex., tailored crusher liners) because its weldability and formability let us match exact equipment needs. Compared to cheaper alternatives, NM450 delivers 2-3x longer service life, which means lower total cost of ownership for our clients. We also provide pre-cut NM450 plates to reduce our customers’ processing time.

FAQ About NM450 Wear Resistant Steel

1. Can NM450 be welded to ordinary steel?
   Oui. Use low-hydrogen electrodes (par ex., E7018-G) and preheat the NM450 to 150 – 200°C before welding. Post-weld tempering (250°C pour 1 heure) helps reduce stress.
2. What thicknesses of NM450 are available?
   NM450 is commonly sold in plates from 3 mm à 100 mm d'épaisseur. For custom orders (par ex., 120 mm d'épaisseur), les délais sont 2-4 semaines.
3. How does NM450 perform in cold weather?
   Excellent. Its impact toughness is ≥25 J at -40°C, so it works well in cold regions (par ex., northern Canada, Siberia) sans craquer.