38CrSi is a high-strength alloy steel widely used in mechanical and automotive industries. With chromium and silicon as main alloying elements, 38CrSi offers excellent hardness, wear resistance, and fatigue strength after quenching and tempering.
This steel grade is ideal for gears, shafts, springs, and other mechanical parts that require high strength and durability under heavy load conditions. It is internationally recognized as SAE 6150 / EN 41CrSiMo7-6, ensuring compatibility with global engineering standards.
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Chemical Composition (%)
| Element | Content |
|---|---|
| C | 0.35 – 0.43 |
| Si | 1.0 – 1.3 |
| Mn | 0.50 – 0.80 |
| Cr | 0.80 – 1.10 |
| P | ≤ 0.035 |
| S | ≤ 0.035 |
Mechanical Properties (After Quenching & Tempering)
| Property | Value |
|---|---|
| Tensile Strength | 950 – 1200 MPa |
| Yield Strength | ≥ 750 MPa |
| Elongation | ≥ 12% |
| Hardness (HRC) | 28 – 35 (after tempering) |
Key Features
High tensile and yield strength
Excellent wear and fatigue resistance
Hardenable via quenching and tempering
Good toughness and machinability
Suitable for high-load industrial and automotive components
Heat Treatment Guidelines
Quenching: 830–870°C, oil or water cooling
Tempering: 180–220°C for mechanical parts; higher for wear resistance
Provides optimal combination of hardness, toughness, and fatigue strength
Products Applications
Gears and gear shafts
Automotive drive shafts and axles
Springs and torsion bars
High-strength mechanical components in machinery
Shafts for engines and transmissions
Physical Properties
| Property | Value |
|---|---|
| Density | 7.85 g/cm³ |
| Melting Point | 1420 – 1460°C |
| Modulus of Elasticity | 210 GPa |
| Thermal Conductivity | 42 W/m·K |
| Coefficient of Thermal Expansion | 12 ×10⁻⁶ /°C |
Welding & Fabrication
Preheating recommended before welding to prevent cracking
Suitable welding methods: TIG, MIG, arc welding
Post-weld heat treatment ensures mechanical strength restoration
International Equivalent Standards
| China GB | SAE / AISI | EN / DIN | ISO |
|---|---|---|---|
| 38CrSi | SAE 6150 | 41CrSiMo7-6 | 6150 |
High Authority Technical Comparison
| Feature | 38CrSi (SAE 6150) | 42CrMo4 | 40Cr |
|---|---|---|---|
| Type | Alloy steel | Alloy steel | Carbon steel |
| Hardness (HRC) | 28–35 | 28–36 | 20–25 |
| Tensile Strength | 950–1200 MPa | 980–1200 MPa | 850–950 MPa |
| Wear Resistance | High | Medium | Medium |
| Applications | Shafts, Gears, Springs | Shafts, Gears | Shafts, Machinery parts |
FAQ
1️⃣ What is 38CrSi steel?
38CrSi is a high-strength alloy steel with chromium and silicon as main alloying elements. It is known for high tensile strength, wear resistance, and fatigue resistance, widely used in mechanical, automotive, and industrial applications.
2️⃣ What are the international equivalents of 38CrSi?
SAE / AISI: 6150
EN / DIN: 41CrSiMo7-6
ISO: 6150
3️⃣ What is the difference between 38CrSi and 42CrMo4?
38CrSi offers better wear resistance and toughness in some applications.
42CrMo4 has slightly higher tensile strength but similar hardness.
38CrSi is ideal for shafts, gears, and springs, while 42CrMo4 is common in heavy machinery parts.
4️⃣ Can 38CrSi be hardened?
Yes, through quenching and tempering. Proper heat treatment achieves 28–35 HRC hardness with high tensile and fatigue strength.
5️⃣ What are the typical applications of 38CrSi steel?
Shafts and gear shafts
Springs and torsion bars
Automotive drive shafts and axles
High-strength mechanical components in machinery
Transmission parts and engine components
6️⃣ Is 38CrSi weldable?
Yes, but preheating is recommended to avoid cracking. Post-weld tempering restores hardness and strength. Suitable methods include TIG, MIG, and arc welding.
7️⃣ How should 38CrSi be machined?
Best machined after annealing.
Hardened components require sharp tools and appropriate feed rates.
Machining in tempered state is possible but requires coolant and careful cutting.
8️⃣ What are the mechanical properties of 38CrSi?
Tensile Strength: 950–1200 MPa
Yield Strength: ≥ 750 MPa
Elongation: ≥ 12%
Hardness (HRC): 28–35 (after tempering)
9️⃣ Can 38CrSi be used in high-load applications?
Yes, it is widely used in engine shafts, transmission gears, automotive axles, and mechanical springs due to its high strength, fatigue resistance, and wear resistance.
10️⃣ What is the heat treatment process for 38CrSi?
Quenching: 830–870°C, oil or water cooling
Tempering: 180–220°C for mechanical parts; higher for wear resistance
Provides optimal hardness, toughness, and fatigue strength for industrial and automotive components.
11️⃣ What forms of 38CrSi are available?
Round bars / Forged bars
Plates and sheets
Tubes and pipes
Springs and precision components
12️⃣ Why choose 38CrSi over other alloy steels?
Balanced wear resistance, toughness, and machinability
Can be hardened and tempered for specific mechanical properties
Recognized by international standards (SAE 6150, 41CrSiMo7-6)
Widely used in industrial, automotive, and high-stress mechanical applications
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