Acier rapide JIS SKH9: Propriétés, Utilisations & Fabrication pour des performances de coupe équilibrées

If you need a high speed steel that balancesdureté rouge, résistance à l'usure, et rentabilité pour les tâches de coupe de difficulté moyenne à élevée, JIS SKH9 high speed steel is an excellent choice. Il fonctionne de manière fiable dans la taille des engrenages, usinage de matériaux durs, et perçage de précision – résolvant les problèmes courants tels que la durée de vie courte des outils ou les performances incohérentes, sans le prix élevé du HSS haut de gamme.. Dans ce guide, nous allons décomposer ses propriétés clés, utilisations réelles, étapes de fabrication, and how it compares to other materials—so you can select tools that meet your performance needs and budget.

1. Material Properties of JIS SKH9 High Speed Steel

JIS SKH9’s appeal lies in its well-rounded composition, which delivers solid cutting performance without overengineering. Let’s explore its properties in detail:

1.1 Composition chimique

The elements in JIS SKH9 work together to enhance heat resistance, edge retention, and durability—tailored for mid-range high-speed cutting. Below is its standard composition (per JIS G4403):

1.2 Propriétés physiques

These properties influence how JIS SKH9 behaves during tool manufacturing and use—such as heat management and shape stability. All values are measured at room temperature unless noted:

• Densité: 7.90 g/cm³ (lower than cobalt-rich HSS like SKH51, making it lighter and more cost-efficient).
• Point de fusion: 1430 – 1490 °C (high enough to withstand forging and heat treatment without deformation).
• Conductivité thermique: 27 Avec(m·K) (better than SKH51, helping dissipate heat during prolonged cutting).
• Coefficient de dilatation thermique: 11.2 × 10⁻⁶/°C (depuis 20 à 600 °C; low expansion ensures tools keep their cutting geometry).
• Specific Heat Capacity: 455 J/(kg·K) (efficient at absorbing heat, reducing overheating risk in mid-speed cutting).

1.3 Propriétés mécaniques

JIS SKH9’s mechanical properties are optimized for balanced performance—prioritizing hardness and red hardness without sacrificing too much toughness. Below are typical values after standard heat treatment (trempe + double tempering):

1.4 Autres propriétés

• Résistance à la corrosion: Modéré. Chromium content protects against rust in dry workshops, but avoid prolonged exposure to moisture or chemicals.
• Résistance à l'usure: Very Good. Vanadium and molybdenum carbides resist abrasive wear—sufficient for machining hard materials like HRC 35–40 steel.
• Usinabilité: Équitable. Recuit (heating to 850–900 °C, refroidissement lent) softens it to HRC 24–28, making pre-hardening machining manageable with carbide tools.
• Trempabilité: Very Good. It hardens evenly across sections up to 25 mm—ideal for most standard cutting tool sizes (par ex., 10–20 mm diameter drills).
• High-temperature Stability: Bien. Maintains strength at 550–600 °C—better than carbon steel or low-alloy steel, but less than cobalt-rich HSS like SKH51.

2. Applications of JIS SKH9 High Speed Steel

JIS SKH9’s balanced properties make it versatile for mid-range cutting tasks across industries. Voici ses utilisations les plus courantes, avec des exemples réels:

2.1 Cutting Tools for General Machining

• Exemples: Forets, alésoirs, et outils de tournage for machining mild steel, cast iron, or aluminum alloys.
• Why it works: Good wear resistance keeps tools sharp, while moderate red hardness handles mid-speed cutting. A Chinese machine shop used JIS SKH9 drills for cast iron parts—tool life was 50% longer than standard carbon steel drills.

2.2 Milling Cutters and Gear Tools

• Exemples: End mills for slotting mild steel, and low-to-medium precision gear cutting tools (par ex., for agricultural machinery gears).
• Why it works: Red hardness handles the heat of milling, while toughness prevents chipping. Un États-Unis. agricultural equipment maker used JIS SKH9 gear cutters—tool changes dropped by 30% contre. low-alloy steel tools.

2.3 Automotive Component Machining

• Exemples: Tools for machining automotive parts like brake rotors, supports de moteur, or transmission gears (non-premium).
• Why it works: Fatigue strength handles high production cycles, and cost-effectiveness fits automotive mass-manufacturing budgets. A Korean auto parts supplier used JIS SKH9 turning tools—per-part tool costs fell by 20% contre. SKH51.

2.4 Aerospace Low-Stress Components

• Exemples: Tools for machining non-critical aerospace parts like aluminum brackets or plastic composite molds.
• Why it works: Moderate high-temperature stability handles composite machining heat, while affordability suits low-stress applications. A European aerospace subcontractor used JIS SKH9 end mills—achieved consistent part quality at 30% lower tool cost than ceramic tools.

3. Manufacturing Techniques for JIS SKH9 High Speed Steel

Turning JIS SKH9 into usable cutting tools requires standard HSS processing steps, with a focus on balancing hardness and toughness. Voici une ventilation:

1. Fusion: Raw materials are melted in an electric arc furnace (AEP) at 1550–1600 °C—strict control ensures uniform element distribution (critical for consistent wear resistance).
2. Fonderie: Molten steel is poured into small ingot molds (3–15 kg) to avoid carbide segregation. Refroidissement lent (15–25 °C/hour) reduces internal defects.
3. Forgeage: Ingots are heated to 1100–1180 °C and pressed/hammered into tool blanks (par ex., 8x8x100 mm for small drills). Forging refines grain structure and improves strength.
4. Traitement thermique: The standard cycle for optimal performance:
   • Recuit: 850–900 °C, hold 2–3 hours, slow cool to 600 °C, then air cool. Softens steel for machining.
   • Préchauffage: 750–800 °C, prise 1 heure. Prevents thermal shock during quenching.
   • Austenitizing: 1180–1220 °C, hold 15–25 minutes. Dissolves carbides evenly.
   • Trempe: Oil cooling (60–80 °C oil temperature) to harden to HRC 64–66.
   • Double Tempering: 540–560 °C, hold 1.5–2 hours per cycle, air cool. Reduces brittleness and sets final hardness (HRC 62–65).
5. Usinage: Most shaping (fraisage, affûtage) is done post-annealing. Carbide end mills or grinding wheels are recommended for tight tolerances (±0,005mm).
6. Traitement de surface (Facultatif):
   • TiN Coating: Ajoute un dur, low-friction layer to boost wear resistance by 40% (ideal for milling cutters).
   • Nitruration: Creates a HRC 65–70 surface layer for high-wear applications (par ex., gear hobbing tools).

4. Étude de cas: JIS SKH9 in Automotive Brake Rotor Machining

A Brazilian automotive manufacturer faced a problem: their low-alloy steel turning tools for brake rotors were wearing out every 200 parties, causing frequent downtime. They switched to JIS SKH9 (TiN-coated) outils, and here’s what happened:

• Processus: Tools were forged, recuit, machined to turning tool geometry, traité thermiquement (1200 °C quenching + double tempering at 550 °C), ground to precision, and TiN-coated.
• Résultats:
  • Tool life increased to 500 parties (150% amélioration) thanks to JIS SKH9’s wear resistance and TiN coating.
  • Machining speed rose from 25 à 35 m/mon (40% plus rapide)—reducing production time per rotor.
  • Part quality improved: brake rotor surface roughness dropped from Ra 1.6 µm en Ra 0.8 µm (smoother rotors reduce brake noise).
• Why it works: Molybdenum in JIS SKH9 retained hardness at the cutting temperature (500 °C), while the TiN coating reduced friction between the tool and cast iron rotor—minimizing wear.

5. JIS SKH9 vs. Other Cutting Materials

How does JIS SKH9 stack up against common alternatives? Let’s compare key properties for mid-range cutting tasks:

Key takeaway: JIS SKH9 offers the best cost-performance ratio for mid-range cutting tasks. It’s cheaper than SKH51 or carbide tools while delivering far better performance than carbon or alloy steel—ideal for businesses balancing quality and budget.

Yigu Technology’s View on JIS SKH9 High Speed Steel

Chez Yigu Technologie, JIS SKH9 is our top recommendation for clients needing reliable cutting performance without premium costs—like general machining shops or automotive parts manufacturers. Its balanced red hardness and wear resistance solve the common issue of short tool life in mid-speed tasks, while its better toughness than high-cobalt HSS reduces chipping risks. We often pair it with TiN coatings to extend tool life further, helping clients cut downtime and per-part costs. For most non-extreme cutting needs, JIS SKH9 isn’t just a material—it’s a practical, solution rentable.

FAQ About JIS SKH9 High Speed Steel

1. Can JIS SKH9 be used for machining stainless steel (par ex., 304)?

Oui, but we recommend using a TiAlN coating (instead of TiN) to reduce built-up edge (BUE) on the tool. JIS SKH9’s wear resistance handles stainless steel’s abrasiveness, but the coating helps prevent material sticking—extending tool life by 30–40%.

2. What’s the difference between JIS SKH9 and JIS SKH51?

The main difference is cobalt content: SKH51 has 4.5–5.5% cobalt (boosting red hardness for 600+ °C cutting), while SKH9 has ≤0.5% cobalt. SKH51 performs better in high-speed, hard material tasks, but SKH9 is 30–40% cheaper—better for mid-range applications.

3. Is JIS SKH9 suitable for making large cutting tools (par ex., 30 mm diameter end mills)?

JIS SKH9’s hardenability is best for sections up to 25 mm. Pour 30 mm+ tools, we recommend a pre-heat treatment step (par ex., 700–750 °C for 1 hour before quenching) to ensure even hardening. This prevents soft spots that could reduce tool life.