15CrNi4MoA is a low-carbon alloy carburizing steel widely used in high-load gears and shafts. It is designed to achieve a hard, wear-resistant surface after carburizing while maintaining a tough, ductile core, making it ideal for heavy-duty transmission components.
Key alloying elements:
Chromium (Cr): improves hardenability and wear resistance
Nickel (Ni): enhances toughness and impact resistance
Molybdenum (Mo): increases strength and reduces temper embrittlement
Compared to conventional carburizing steels like 20CrMnTi:
Deeper carburized case depth
Better fatigue resistance under heavy load
Improved impact performance for large gears
Applications include automotive transmissions, heavy machinery, and industrial gear systems.
Chemical Composition (wt%)
| Element | Content (%) |
|---|---|
| C | 0.12 – 0.18 |
| Si | 0.17 – 0.37 |
| Mn | 0.40 – 0.70 |
| Cr | 0.80 – 1.10 |
| Ni | 1.30 – 1.70 |
| Mo | 0.15 – 0.30 |
| P | ≤ 0.025 |
| S | ≤ 0.025 |
Specifications & Dimensions
| Product Type | Size Range | Length | Standard |
|---|---|---|---|
| Round Bar | 20 – 500 mm (0.79" – 19.7") | 3 – 12 m | GB/T 3077 |
| Forged Bar | 80 – 1000 mm (3.15" – 39.4") | Custom | GB |
| Steel Plate | 10 – 200 mm (0.39" – 7.87") | Custom | GB |
| Gear Forgings | As per drawings | Custom | EN / ASTM |
Tolerance: ASTM A29 / EN 10060
Surface Condition: Black / Peeled / Turned / Polished
Mechanical Properties (After Carburizing & Q&T)
| Property | Value |
|---|---|
| Surface Hardness | 58 – 62 HRC |
| Core Tensile Strength | ≥ 900 MPa |
| Core Yield Strength | ≥ 700 MPa |
| Elongation | ≥ 10% |
| Impact Energy | ≥ 55 J |
Heat Treatment Process
Carburizing: 900 – 940°C
Quenching: Oil quenching
Tempering: 150 – 200°C
Benefits:
Hard, wear-resistant surface
Tough and ductile core
High fatigue life for gear components
Key Features & Advantages
Excellent Carburizing Performance – Deep, uniform hardened layer.
High Core Toughness – Nickel improves impact resistance.
Superior Fatigue Strength – Ideal for cyclic loading.
Wear Resistance – Long service life under heavy load.
Stable Heat Treatment – Uniform properties in thick sections.
Applications
Heavy-duty gears and shafts
Automotive transmission systems
Mining machinery
Industrial gearboxes
Power transmission equipment
Comparison with Similar Grades
| Grade | Carburizing Depth | Toughness | Application |
|---|
| 15CrNi4MoA | ⭐⭐⭐⭐⭐ | ⭐⭐⭐⭐⭐ | Heavy-duty gears & shafts |
| 20CrMnTi | ⭐⭐⭐ | ⭐⭐⭐ | General gears |
| 18CrNiMo7-6 | ⭐⭐⭐⭐⭐ | ⭐⭐⭐⭐⭐ | High-end gear systems |
Inspection & Quality Assurance
Chemical composition analysis
Mechanical testing (tensile, impact, hardness)
Case depth inspection
Ultrasonic Testing (UT)
Metallographic analysis
✅ Third-party inspection: SGS / BV / TUV
✅ Certification: EN 10204 3.1 / 3.2
Product Delivery Standards
Delivery Condition: Annealed / Normalized / Pre-machined
Packaging: Seaworthy export packing
Delivery Time: 10–25 days
Custom forging & machining services available
FAQ – Frequently Asked Questions
Q1: What is 15CrNi4MoA used for?
A1: Heavy-duty gears, gear shafts, and transmission components.
Q2: What is the hardness after carburizing?
A2: 58–62 HRC surface hardness with a tough core.
Q3: Is it better than 20CrMnTi?
A3: Yes, it offers deeper case depth, better fatigue resistance, and higher toughness.
Q4: Can you supply gear forgings?
A4: Yes, custom gear blanks and forgings are available.
Q5: Do you provide inspection certificates?
A5: Yes, EN 10204 3.1 / 3.2 certificates are available.
Contact Us
Looking for a reliable 15CrNi4MoA (EX30) alloy steel supplier?
Custom sizes & gear forgings
Competitive pricing
Fast global delivery
+8615769214734
office@dongmjd.com
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