30CrNi4MoA (EN30B) is a low-carbon Ni-Cr-Mo alloy carburizing steel designed for heavy-duty gears, shafts, and transmission components. It produces a hard, wear-resistant surface while maintaining a tough, ductile core, ensuring long-term reliability under high load and cyclic stress.
Key Alloying Elements:
Chromium (Cr): increases hardenability and surface wear resistance
Nickel (Ni): improves toughness and impact resistance
Molybdenum (Mo): enhances strength and reduces temper embrittlement
Compared with 20CrMnTi and other carburizing steels:
Achieves deeper case hardening
Provides higher fatigue resistance and toughness
Performs reliably in large-diameter gears and heavy shafts
Common applications include automotive transmission systems, industrial machinery, and heavy-duty gearboxes.
Chemical Composition (wt%)
| Element | Content (%) |
|---|---|
| C | 0.28 – 0.34 |
| Si | 0.17 – 0.37 |
| Mn | 0.50 – 0.80 |
| Cr | 1.30 – 1.70 |
| 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 / EN |
| Steel Plate | 10 – 200 mm (0.39" – 7.87") | Custom | GB / EN |
| 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 – 63 HRC |
| Core Tensile Strength | ≥ 950 MPa |
| Core Yield Strength | ≥ 700 MPa |
| Elongation | ≥ 10% |
| Impact Energy | ≥ 60 J |
Heat Treatment Process
Carburizing: 900 – 940°C
Quenching: Oil quenching
Tempering: 150 – 200°C
Benefits:
Deep, uniform hardened surface
Tough and ductile core
High fatigue resistance
Long-lasting wear resistance
Key Features & Advantages
Deep Carburizing Performance – Ideal for heavy gears and shafts.
High Core Toughness – Nickel enhances impact resistance.
Superior Fatigue Strength – Designed for high-load cyclic conditions.
Excellent Wear Resistance – Durable surface for long-term use.
Stable Heat Treatment Performance – Uniform properties in thick sections.
Applications
Automotive transmission gears
Industrial gearboxes and shafts
Heavy-duty machinery components
Mining equipment transmission parts
High-load power transmission systems
Comparison with Similar Grades
| Grade | Carburizing Depth | Toughness | Application |
|---|---|---|---|
| 30CrNi4MoA (EN30B) | ⭐⭐⭐⭐⭐ | ⭐⭐⭐⭐⭐ | Heavy-duty gears & shafts |
| 20CrMnTi | ⭐⭐⭐ | ⭐⭐⭐ | General gear applications |
| 18CrNiMo7-6 | ⭐⭐⭐⭐⭐ | ⭐⭐⭐⭐ | High-end gear systems |
Inspection & Quality Assurance
Chemical composition analysis
Mechanical property testing
Case depth inspection
Ultrasonic Testing (UT)
Metallographic examination
✅ 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: 10–30 days
Custom forgings and machining services available
FAQ – Frequently Asked Questions
Q1: What is 30CrNi4MoA used for?
A1: Heavy-duty gears, gear shafts, and high-load transmission components.
Q2: What is the surface hardness after carburizing?
A2: 58–63 HRC, with a tough, ductile core.
Q3: Is it superior to 20CrMnTi?
A3: Yes, it has deeper case depth, higher fatigue resistance, and better toughness.
Q4: Can you supply gear forgings?
A4: Yes, custom gear blanks and shafts are available.
Q5: Are inspection certificates provided?
A5: Yes, EN 10204 3.1 / 3.2 certificates are provided.
Contact Us
Looking for a reliable 30CrNi4MoA (EN30B) alloy steel supplier?
Custom sizes & gear forgings
Competitive pricing
Fast global delivery
+8615769214734
office@dongmjd.com
Hot Tags: 30crni4moa (en30b) alloy steel, China 30crni4moa (en30b) alloy steel manufacturers, suppliers, factory
