Description
35CrMo Alloy Steel: Comprehensive Guide
35CrMo is a high-strength, low-alloy steel known for its excellent mechanical properties and versatility. This alloy steel is frequently used in various engineering and industrial applications due to its ability to maintain strength and toughness under high-stress conditions.
Key Features of 35CrMo Alloy Steel:
- High Strength: Provides superior tensile and yield strength.
- Toughness: Excellent impact resistance and toughness.
- Wear Resistance: Shows good resistance to wear and abrasion.
- Heat Treatability: Capable of being heat treated to achieve desired mechanical properties.
Applications of 35CrMo Alloy Steel
35CrMo alloy steel is used in applications where high strength and durability are required. Its properties make it suitable for components that undergo significant stress and wear.
Typical Applications Include:
- Automotive Parts: Gear shafts, crankshafts, and camshafts.
- Engineering Components: High-load bearings, heavy-duty gears, and structural parts.
- Industrial Machinery: Components in manufacturing and processing equipment.
- Aerospace: Structural and high-stress parts in aircraft and spacecraft.
Equivalent Grades of 35CrMo Alloy Steel
35CrMo alloy steel is recognized under different designations in various international standards, ensuring compatibility and flexibility in global markets.
| Standard | Equivalent Grade |
|---|---|
| DIN | 35CrMo |
| EN | 1.7218 |
| AISI/SAE | 4130 |
| BS | 708M40 |
| UNS | G41300 |
Chemical Composition of 35CrMo Alloy Steel
The chemical composition of 35CrMo is crucial for achieving its high strength and toughness. The following table outlines the typical composition:
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.32 – 0.38 |
| Silicon (Si) | 0.17 – 0.37 |
| Manganese (Mn) | 0.40 – 0.70 |
| Phosphorus (P) | ≤ 0.035 |
| Sulfur (S) | ≤ 0.035 |
| Chromium (Cr) | 0.80 – 1.10 |
| Molybdenum (Mo) | 0.15 – 0.30 |
This composition ensures the steel’s high strength, toughness, and resistance to wear.
Mechanical Properties of 35CrMo Alloy Steel
The mechanical properties of 35CrMo highlight its performance in high-stress applications. The following table summarizes these properties:
| Property | Value (Typical) |
|---|---|
| Tensile Strength (MPa) | 680 – 830 |
| Yield Strength (MPa) | 450 – 650 |
| Elongation (%) | ≥ 12 |
| Impact Toughness (J) | ≥ 40 (at room temperature) |
| Hardness (HB) | 200 – 250 |
These values indicate the alloy’s capability to withstand high stresses and impacts.
Heat Treatment of 35CrMo Alloy Steel
Heat treatment processes are used to optimize the mechanical properties of 35CrMo. The following processes are commonly employed:
- Hardening: Heat to 850 – 880°C and quench in oil or water to achieve high hardness and strength.
- Tempering: Heat to 550 – 650°C after hardening to improve toughness and reduce brittleness.
- Normalizing: Heat to 850 – 880°C and air cool to refine grain structure and enhance toughness.
These heat treatments allow for customization of the steel’s properties for different applications.
Hardness of 35CrMo Alloy Steel
The hardness of 35CrMo varies depending on the heat treatment it undergoes. Typical hardness values are:
- Annealed Condition: 190 – 210 HB
- After Hardening and Tempering: Up to 50 HRC
These hardness values reflect the steel’s ability to provide high strength and wear resistance.
Physical Properties of 35CrMo Alloy Steel
The physical properties of 35CrMo ensure its stability and performance across various conditions. The following table summarizes these properties:
| Property | Value |
|---|---|
| Density (g/cm³) | 7.85 |
| Melting Point (°C) | 1420 – 1450 |
| Thermal Conductivity (W/m·K) | 30 – 35 |
| Specific Heat Capacity (J/kg·K) | 460 – 480 |
These properties contribute to the alloy’s reliability in different environments.
Forging Properties of 35CrMo Alloy Steel
35CrMo can be forged within the temperature range of 1150 – 1250°C. It is crucial to cool the forged components slowly to avoid internal stresses and maintain dimensional stability.
Stress Relieving for 35CrMo Alloy Steel
Stress relieving involves heating the steel to 600 – 650°C to remove residual stresses from machining or forming. This process helps improve dimensional stability and reduce the risk of deformation.
Normalizing 35CrMo Alloy Steel
Normalizing is performed by heating the steel to 850 – 880°C and allowing it to cool in air. This process enhances toughness and refines the grain structure, improving overall mechanical properties.
Annealing 35CrMo Alloy Steel
Annealing involves heating the steel to 680 – 720°C and cooling it slowly in the furnace. This process enhances machinability and prepares the steel for further heat treatments.
Machinability of 35CrMo Alloy Steel
35CrMo alloy steel exhibits good machinability, especially in its annealed condition. It can be machined into complex shapes with standard cutting tools, although care should be taken to manage tool wear during high-hardness operations.
Welding of 35CrMo Alloy Steel
Welding of 35CrMo is feasible with proper preheating (to about 150 – 200°C) and post-weld heat treatment. Following appropriate welding procedures helps prevent issues such as cracking or reduced toughness.
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