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30CrMnSiA is a high-strength low-alloy steel widely used in automotive, mechanical, and industrial applications. With chromium, manganese, and silicon as main alloying elements, it provides excellent tensile strength, toughness, and fatigue resistance after quenching and tempering.
It is ideal for gears, shafts, automotive components, and mechanical parts requiring high performance under heavy load and high-stress conditions. Internationally, it is recognized as SAE 5115 / EN 30CrMnSiA, ensuring compatibility with global industrial standards.
SEO Keywords Embedded: 30CrMnSiA steel, SAE 5115, 30CrMnSiA alloy steel, high-strength low-alloy steel, quenched and tempered steel, gears, shafts, automotive parts.
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Chemical Composition (%)
| Element | Content |
|---|---|
| C | 0.28 – 0.35 |
| Si | 0.17 – 0.37 |
| 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 | 900 – 1100 MPa |
| Yield Strength | ≥ 720 MPa |
| Elongation | ≥ 12% |
| Hardness (HRC) | 28 – 35 (after tempering) |
Key Features
High tensile and yield strength
Excellent toughness and fatigue resistance
Hardenable via quenching and tempering
Good wear resistance and machinability
Suitable for high-load automotive and industrial components
Heat Treatment Guidelines
Quenching: 830–870°C, oil or water cooling
Tempering: 180–220°C for mechanical parts; higher for wear-resistant applications
Provides optimal hardness, toughness, and fatigue strength
Applications
Automotive drive shafts and axles
Gears and gear shafts
Springs and torsion bars
Engine components and mechanical shafts
High-strength machinery parts
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 restores mechanical strength
International Equivalent Standards
| China GB | SAE / AISI | EN / DIN | ISO |
|---|---|---|---|
| 30CrMnSiA | SAE 5115 | 30CrMnSiA | 5115 |
Industry Case Studies
Case 1: Automotive Drive Shafts
Material: 30CrMnSiA Alloy Steel (SAE 5115)
Process: Quenched and tempered to HRC 32–35
Benefit: High tensile strength and fatigue resistance ensure long-term durability under high torque
Outcome: Reduced shaft deformation and increased service life by 25–30% compared to 40Cr steel
Case 2: Industrial Gears
Material: 30CrMnSiA Alloy Steel
Process: Hardened and tempered after precision machining
Benefit: Excellent wear resistance extends gear lifespan in heavy-duty machinery
Outcome: Gear wear reduced by 20–25% compared to 42CrMo4 steel
Case 3: Automotive Springs
Material: 30CrMnSiA Steel
Process: Heat treated to HRC 30–34
Benefit: High elasticity and fatigue resistance allow repeated load cycles without permanent deformation
Outcome: Maintenance cycle extended by 30%, improving vehicle reliability
Technical Comparison
| Feature | 30CrMnSiA (SAE 5115) | 42CrMo4 | 40Cr | Notes |
|---|---|---|---|---|
| Type | Low-alloy chromium steel | Chromium-molybdenum steel | Carbon steel | 30CrMnSiA optimized for toughness & wear |
| Hardness (HRC) | 28–35 | 28–36 | 20–25 | 30CrMnSiA balances hardness & fatigue resistance |
| Tensile Strength | 900–1100 MPa | 980–1200 MPa | 850–950 MPa | Comparable to 42CrMo4 but better fatigue |
| Yield Strength | ≥ 720 MPa | ≥ 740 MPa | ≥ 600 MPa | 30CrMnSiA slightly better for elastic applications |
| Wear Resistance | High | Medium | Medium | Optimized for high-load mechanical parts |
| Applications | Shafts, Gears, Springs | Shafts, Gears | Shafts, Machinery | 30CrMnSiA ideal for automotive & industrial |
FAQ – 30CrMnSiA Alloy Steel (SAE 5115 / EN 30CrMnSiA)
1️⃣ What is 30CrMnSiA steel?
30CrMnSiA is a high-strength low-alloy chromium steel with manganese and silicon as key alloying elements. It provides excellent tensile strength, wear resistance, and fatigue resistance, widely used in automotive, mechanical, and industrial applications.
2️⃣ What are the international equivalents of 30CrMnSiA?
SAE / AISI: 5115
EN / DIN: 30CrMnSiA
ISO: 5115
3️⃣ Can 30CrMnSiA be hardened?
Yes, it can be quenched and tempered to achieve high hardness (28–35 HRC) and excellent tensile and fatigue strength.
4️⃣ What are the typical applications of 30CrMnSiA steel?
Automotive drive shafts and axles
Industrial and automotive gears
Springs and torsion bars
Engine components and mechanical shafts
High-strength machinery parts
5️⃣ Is 30CrMnSiA weldable?
Yes, but preheating is recommended to prevent cracking. Post-weld tempering restores hardness and mechanical strength. Suitable welding methods include TIG, MIG, and arc welding.
6️⃣ What is the typical hardness after heat treatment?
Typically 28–35 HRC, depending on quenching and tempering parameters.
Heat treatment ensures optimal combination of toughness, wear resistance, and fatigue strength.
7️⃣ How should 30CrMnSiA be machined?
Best machined in annealed condition.
Hardened components require sharp cutting tools and proper feed rates.
Use coolant during machining to prevent overheating and maintain surface finish.
8️⃣ What forms are available for 30CrMnSiA?
Round bars, forged bars, plates, sheets, tubes, and precision components
Springs and shafts for automotive and mechanical applications
9️⃣ What are the advantages of 30CrMnSiA compared to 42CrMo4 or 40Cr?
Better toughness and wear resistance
Balanced hardness and fatigue resistance
Suitable for high-load, high-stress components
Recognized by international standards (SAE 5115 / EN 30CrMnSiA)
1️⃣0️⃣ What industries commonly use 30CrMnSiA steel?
Automotive: drive shafts, axles, gears, springs
Mechanical engineering: high-strength machinery parts, precision shafts
Industrial: gears, torsion bars, and other high-load components
Contact Us
For inquiries, technical support, or customized solutions regarding 30CrMnSiA (SAE 5115 / EN 30CrMnSiA) alloy steel products, please contact our professional team. We provide fast response, global shipping, and tailored services to meet your automotive, mechanical, and industrial needs.
Our address
Room 4107, Runfeng Building, Sanqiao New Street, Weiyang District, Xi'an City, Shaanxi Province
Phone Number
+8615769214734
office@dongmjd.com
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