1. Specifications & Capability
FUSHUN METAL forges gearbox shafts in 18CrNiMo7-6 (1.6587) and 42CrMo4, 300-800 mm in diameter and up to 12 m long. 18CrNiMo7-6 is a carburizing case-hardening steel combining a tough core with a hard, wear-resistant case; 42CrMo4 is a quenched and tempered (QT) grade for general transmission shafts.
The forging ratio is at least 4:1, keeping a controlled grain flow along the shaft axis for maximum bending and torsion fatigue resistance.
| Grade / Condition (mm) | Rm (MPa) | Rp0.2 (MPa) | A (%) | Surface |
|---|---|---|---|---|
| 18CrNiMo7-6, carburized core | 1050-1300 | 800 min | 8 | 58-62 HRC |
| 42CrMo4, QT up to 250 | 750-950 | 520 min | 14 | – |
| 300-800 | – | – | – | Per spec |
Values follow EN 10084 for the carburizing grade and EN 10250-3 for the QT grade; case depth, core hardness and surface hardness are agreed to the gearbox design specification.
2. Components & Service Conditions
FUSHUN METAL forges the full set of gearbox transmission parts: input and output shafts, planet carriers and sun shafts for epicyclic stages. These components carry high torque and cyclic bending loads inside wind and industrial gearboxes.
Gear tooth flanks demand a hard, wear-resistant surface, while the shaft core must absorb bending and torsional stress without fracture. The carburizing grade 18CrNiMo7-6 satisfies both through a case-hardened surface over a tough core; the QT grade 42CrMo4 is used where uniform through-section strength is sufficient. The higher nickel in 18CrNiMo7-6 gives deep hardenability and a tough core for the case depths typical of gearbox shafts.
3. Grade Equivalents – 18CrNiMo7-6 / 42CrMo4
| Designation | Standard | Notes |
|---|---|---|
| 18CrNiMo7-6 / 1.6587 | EN 10084 | Carburizing case-hardening steel |
| 42CrMo4 / 1.7225 | EN 10250-3 | QT transmission shaft steel |
| AISI 9310 | SAE J404 | US carburizing equivalent |
| SNCM815 | JIS G4053 | Japanese equivalent |
| 20Cr2Ni4A | GB/T 3077 | Reference only, not used in certification |
| Grade | C | Si | Mn | Cr | Ni | Mo |
|---|---|---|---|---|---|---|
| 18CrNiMo7-6 (1.6587) | 0.15-0.21 | 0.40 max | 0.50-0.90 | 1.50-1.80 | 1.40-1.70 | 0.25-0.35 |
| 42CrMo4 (1.7225) | 0.38-0.45 | 0.40 max | 0.60-0.90 | 0.90-1.20 | – | 0.15-0.30 |
The 1.4-1.7% nickel content of 18CrNiMo7-6 provides the deep hardenability required for carburized case depths on gear flanks.
4. Manufacturing Process
Steelmaking. FUSHUN METAL melts in an electric arc furnace with ladle refining and vacuum degassing to keep inclusions low, which is critical for the fatigue resistance of gear teeth.
Forging. The shaft is forged on a 20/80 MN fast forging press with a minimum 4:1 reduction ratio, orienting grain flow along the load path.
Heat treatment. 18CrNiMo7-6 parts are carburized and hardened to the specified case depth and surface hardness; 42CrMo4 parts are quenched and tempered.
Testing. Full-section UT, hardness and case-depth verification, with complete heat traceability for every shaft.
5. Standards & Certification
Gearbox shafts are supplied to EN 10084 (case-hardening steel) and EN 10250-3 (QT steel forgings), with inspection certificates under EN 10204 3.1. FUSHUN METAL holds ISO 9001 and AS9120B certification with complete heat traceability for every shaft.
Related forging: wind turbine main shafts.
6. Typical Applications
Wind gearboxes
Input and output shafts for wind turbine gearboxes.
Planet carriers
Forged planet carriers with integral pinion journals.
Sun shafts
Central sun gear shafts for epicyclic stages.
Industrial gearboxes
Transmission shafts for industrial gearing packages.
7. Inquiry Essentials
To quote your gearbox shaft, please provide the gear shaft drawing, the required carburizing depth or hardness range, the core and surface hardness requirements, and the applicable standard.
