CNC Machining
Alloy Steel
Alloy steels are the backbone of heavy-duty engineering. By incorporating elements like chromium, molybdenum, and nickel, these metals offer exceptional toughness, wear resistance, and high tensile strength. Ideal for critical automotive, aerospace, and industrial applications.
Core Mechanical Properties
Selecting the right alloy steel is critical. Below is the typical mechanical data for the most common CNC machined alloy steels (Note: Values vary significantly based on specific heat treatments).
| Alloy Grade | Yield Strength | Tensile Strength | Rockwell Hardness |
|---|---|---|---|
| 4140 | 415 - 1000 MPa | 655 - 1100 MPa | 28 - 32 HRC |
| 4340 | 470 - 1600 MPa | 745 - 1800 MPa | 32 - 36 HRC |
| 8620 | ~ 360 MPa | ~ 530 MPa | ~ 89 HRB (50+ HRC when case hardened) |
International Grade Comparison
Use our cross-reference chart to match American standards (AISI/SAE) with European (DIN/EN) and Chinese (GB) material equivalents for your global sourcing needs.
| AISI / SAE (USA) | DIN / EN (Europe) | GB (China) | Key Characteristics |
|---|---|---|---|
| 4140 | 42CrMo4 / 1.7225 | 42CrMo | Excellent strength-to-weight ratio. The most versatile and widely used chromium-molybdenum steel. |
| 4340 | 36CrNiMo4 / 1.6511 | 40CrNiMoA | Nickel-chromium-moly steel. Known for deep hardenability and extreme toughness under severe fatigue. |
| 8620 | 20NiCrMo2-2 / 1.6523 | 20CrNiMo | Low carbon content makes it highly receptive to carburizing (case hardening) while retaining a tough core. |
Hardcore Industrial Applications
When aluminum is too weak and carbon steel is too brittle, alloy steel is the only choice. We machine complex features with tight tolerances for critical components.
Power Transmission Gears
Machined from 8620 and case-hardened, these gears endure massive torque loads and surface abrasion without shattering the core.
Aerospace Driveshafts
Utilizing 4340 for its extreme fatigue resistance, these CNC turned shafts transfer power efficiently in critical aviation systems under high stress.
High-Pressure Valves
Precision 5-axis milled from 4140, these hydraulic manifolds and valve bodies safely contain intense fluid pressures without deformation.
Expert Machining Tips
Alloy steel's toughness makes it notoriously difficult to machine. Huade engineers employ specific strategies to maintain tight tolerances and extend tool life:
- 1
Optimized Tool Coatings
Due to high abrasion, uncoated carbide tools fail rapidly. We exclusively use TiAlN (Titanium Aluminum Nitride) or TiCN coated solid carbide tooling to withstand the extreme heat generated at the cutting edge.
- 2
Aggressive Feeds, Lower Speeds
Unlike aluminum, alloy steels require significantly lower spindle speeds (SFM) to prevent tool burn-up. However, maintaining a consistently high feed rate prevents work-hardening of the material surface during passes.
- 3
High-Pressure Coolant Delivery
Alloy steels produce tough, stringy chips. We utilize high-pressure through-spindle coolant systems (1000+ PSI) to effectively break and evacuate chips, preventing them from recutting and marring the surface finish.
Top 3 Surface Treatments
Bare alloy steel will rust rapidly. We provide in-house post-processing to protect your components and enhance mechanical performance.
1. Black Oxide (MIL-DTL-13924)
Provides mild corrosion resistance and anti-galling properties with zero dimensional change. Ideal for precision gears and tight-tolerance threaded parts.
Watch Process Video2. Nitriding / Case Hardening
A thermochemical process that drastically increases surface hardness (up to 60+ HRC) for extreme wear resistance, while maintaining the ductile, tough core of the alloy.
3. Electroless Nickel Plating
Deposits a highly uniform nickel-phosphorus alloy coating. Offers excellent lubricity and superior corrosion protection in harsh chemical or high-humidity environments.
Start Your Manufacturing RFQ
Upload your 3D CAD files today. Our engineering team will review your alloy specifications and provide a free DFM report along with rapid pricing.