Description
38CrMoAl Steel Introduction:
38CrMoAl is a nitriding steel known for its excellent wear resistance, high surface hardness, and good fatigue strength. The key alloying elements in this steel are chromium (Cr), molybdenum (Mo), and aluminum (Al), which make it ideal for nitriding—a process that significantly enhances surface hardness without compromising the core toughness. This makes 38CrMoAl suitable for components subjected to heavy wear and fatigue in demanding environments.
38CrMoAl Grade Applications:
38CrMoAl is widely used in industries where high surface hardness and wear resistance are critical. Common applications include:
- Transmission components such as gears and shafts
- Cylinder liners
- Die-casting tools and molds
- Valve parts
- Spindles and crankshafts
- Plastic mold tools
These parts typically benefit from nitriding treatment, which provides a hard, wear-resistant surface while retaining good core toughness.
Equivalent Grades:
- GB: 38CrMoAl
- DIN: 1.8509 / 34CrAlMo5
- AISI/SAE: Similar to AISI 9840 (for alloy composition, though used in different applications)
- JIS: SACM645
Chemical Composition:
| Element | Content (%) |
|---|---|
| C | 0.35-0.42 |
| Mn | 0.20-0.50 |
| P | ≤ 0.030 |
| S | ≤ 0.030 |
| Cr | 1.35-1.65 |
| Mo | 0.15-0.25 |
| Al | 0.80-1.20 |
| Si | 0.20-0.40 |
Mechanical Properties:
| Property | Value |
|---|---|
| Tensile strength (MPa) | ≥ 950 |
| Yield strength (MPa) | ≥ 780 |
| Elongation rate (%) | ≥ 12 |
| Reduction of area (%) | ≥ 45 |
| Hardness (HB) | ≤ 241 (annealed) |
38CrMoAl Hardness:
In its annealed state, the hardness typically ranges from ≤ 241 HB. After nitriding, the surface hardness can reach up to 850-1100 HV, depending on the nitriding depth and process parameters.
Heat Treatment:
38CrMoAl is usually subjected to a combination of heat treatments, including quenching, tempering, and nitriding.
Nitriding Process:
- Heating for nitriding: The material is heated to 500-550°C in a nitrogen-rich atmosphere, allowing nitrogen to diffuse into the steel surface.
- Hardening: Nitriding forms a hard, wear-resistant surface layer without requiring quenching, which helps maintain core toughness.
Tempering Process: After nitriding, tempering may be applied at 150-200°C to relieve internal stresses and improve dimensional stability.
Physical Properties:
| Property | Value |
|---|---|
| Modulus of Elasticity (N/mm²) | 210 × 10³ |
| Density (g/cm³) | 7.80 |
| Thermal Conductivity (W/m.K) | 46.5 |
Thermal Properties:
- Thermal conductivity: 46.5 W/m.K at room temperature.
- Specific heat: 460 J/kg-K.
Forging Properties:
Forging is performed at temperatures between 1100°C and 850°C. After forging, slow cooling is recommended to avoid internal stress and cracking.
Normalizing:
Normalize the steel at 880-920°C, followed by air cooling, to refine the grain structure and improve toughness.
Annealing:
Annealing is typically carried out at 850°C, followed by slow cooling in a furnace to improve machinability and prepare the material for further processing.
Welding:
38CrMoAl is weldable, but the material may require preheating and post-weld heat treatment to relieve stresses and avoid cracking, particularly in large or thick sections.
Supply Cities:
Mumbai Ahmedabad, Amaravathi, Ambattur, Bangalore, Belgaum, Chennai, Chittoor, Coimbatore, Dindigul, Mysore, Nellore, Hyderabad, Kochi, Mangalore, Tirupur, Tuticorin, Madurai, Andhra Pradesh, Karnataka, Puducherry, Kerala, Tamil Nadu, Telangana, Visakhapatnam, Kochi, Kerala, Hubli-Dharwad, Karnataka, Ghaziabad Kolkata.
