40Cr Vacuum Oil Quenching Process

I. 40Cr Typical Applications (Most Common and Core Uses)

40Cr exhibits excellent comprehensive mechanical properties and possesses significantly higher hardenability compared to carbon steels.

Primarily used for:

• Shaft Components: Transmission shafts, spindles, camshafts, worm gears, spline shafts
• Gears and Transmission Parts: Medium-load gears, gear shafts, couplings, sprockets
• Bolts and Fasteners: Grade 8.8 and Grade 10.9 high-strength bolts and studs
• Connecting Rods, Pins, and Molds: Small to medium-sized forging dies, ejector pins, guide pillars, bushings
• Hydraulic / Pneumatic Components: Piston rods, cylinder barrels, valve cores

Key Features:

• After Quenching and Tempering: High strength, good toughness, and excellent fatigue resistance
• Suitable for Surface Hardening: Enhances wear resistance (achieving approximately HRC 50)

II. Oil Quenching Process

① Heating and Soaking

• Heating Temperature: 840–860°C
• Vacuum Level: 10⁻¹–10⁻² Pa (Low vacuum to prevent decarburization)
• Soaking Time: Calculated based on effective thickness: 1.2–1.5 min/mm; ensures thorough heating and uniform composition.

② Vacuum Oil Quenching (Critical Step)

1. Quenching Medium: Fast-acting bright quenching oil
2. Cooling Method: Initial gas cooling to 780–800°C, followed by oil quenching; the workpiece must be fully immersed in the oil.
3. Agitation: Moderate-to-strong agitation to ensure uniform cooling and minimal deformation.
4. Oil Exit Temperature: ≤ 150°C before removal from the furnace.

③ High-Temperature Tempering (Mandatory; otherwise, cracking is likely)

• Tempering Temperature: 520–600°C
• Soaking Time: 2–3 hours
• Cooling: Air cooling

III. Post-Heat Treatment Properties (Typical)

• Hardness: 240–280 HB
• Tensile Strength: ≥ 980 MPa
• Yield Strength: ≥ 785 MPa
• Impact Toughness: Good; suitable for applications involving dynamic loads.

IV. Advantages of Vacuum Oil Quenching

• No oxidation, no decarburization, bright surface finish
• Minimal deformation; suitable for precision components
• Stable quality; suitable for mass production
• Environmentally friendly and safe

SIMUWU’s VQGQ series vacuum oil quenching furnace is a high-quality product for vacuum heat treatment processes of materials such as carbon steel, tool steel, mold steel, high-speed steel, and ultra-high-strength steel.  Excellent temperature control accuracy and uniformity ensure the effective vacuum quenching process. SIMUWU focuses on the manufacturing of vacuum furnaces and has more than ten years of relevant experience, enjoying a good reputation in the field of vacuum furnace manufacturing. The product line includes vacuum gas quenching furnaces, vacuum oil quenching furnaces, and vacuum brazing furnaces, which are widely sold to developed and developing countries.

If you would like to learn more about vacuum furnace equipment, please contact us, and our company will provide you with a satisfactory solution.