1. Specifications & Capability
FUSHUN METAL forges turbine discs and wheels to ASTM A294, 500-1200 mm in diameter, in 34CrNiMo6 (1.6582) and AISI 4340. These are the bladed discs of industrial steam turbines, supplied forged, heat treated, machined and dynamically balanced to the turbine maker’s drawing.
The forging ratio is at least 4:1, with the disc upset and drawn so the grain flows radially, giving maximum strength in the direction of centrifugal load. Properties are verified on separately forged prolonged test pieces.
| Grade | Standard | Typical Use |
|---|---|---|
| ASTM A294 | ASTM A294 | Turbine wheels and discs |
| 34CrNiMo6 / 1.6582 | EN 10250-3 | Disc and wheel steel |
| AISI 4340 | SAE J404 | US equivalent |
2. Components & Service Conditions
These forgings are the shrunk-on discs and wheel bodies of industrial steam turbines, carrying the blading at working temperatures up to about 435 C for smaller units. The disc experiences the highest hoop stress in the machine from centrifugal loading, concentrated at the bore.
Because the stress peaks at the hub, the disc must be sound and homogeneous at the bore, which is why forging – with its radial grain flow and closed porosity – is specified over a casting. The quenched and tempered 34CrNiMo6 or AISI 4340 gives the required strength and toughness, and each disc is machined and dynamically balanced to limit vibration in service.
3. Grade Equivalents – ASTM A294 / 34CrNiMo6
| Designation | Standard | Notes |
|---|---|---|
| ASTM A294 | ASTM A294 | Turbine wheels and discs |
| 34CrNiMo6 / 1.6582 | EN 10250-3 | QT disc steel |
| AISI 4340 | SAE J404 | US equivalent |
| A470 / A788 / A891 | ASTM | Related modern specifications |
| 34CrNi3Mo | GB/T 8732 | Reference only, not used in certification |
| Grade | C | Si | Mn | Cr | Ni | Mo |
|---|---|---|---|---|---|---|
| 34CrNiMo6 (1.6582) | 0.30-0.38 | 0.40 max | 0.50-0.80 | 1.30-1.70 | 1.30-1.70 | 0.15-0.30 |
| AISI 4340 | 0.38-0.43 | 0.15-0.35 | 0.60-0.80 | 0.70-0.90 | 1.65-2.00 | 0.20-0.30 |
The nickel content improves hardenability and toughness at the hub, where the centrifugal stress concentrates.
4. Manufacturing Process
Steelmaking. FUSHUN METAL melts in an electric arc furnace with ladle refining and vacuum degassing to keep inclusions low and secure hub soundness.
Forging. The disc is upset and drawn with a minimum 4:1 reduction ratio so the grain flows radially, then quenched and tempered to the ordered strength and toughness.
Machining & balancing. Each disc is machined to the turbine drawing and dynamically balanced to limit vibration in service.
Testing. Full-section UT, MT at the bore, and mechanical tests, with full traceability.
5. Standards & Certification
Turbine discs and wheels are supplied to ASTM A294 (turbine wheels and discs), with inspection certificates under EN 10204 3.1 and optional 3.2 third-party inspection. FUSHUN METAL holds ISO 9001 and AS9120B certification.
Related forging: turbine and compressor discs.
6. Typical Applications
Industrial steam turbines
Shrunk-on discs and wheels for industrial turbines.
Small turbine units
Wheel bodies for smaller turbine sets.
Mechanical drive
Discs for turbine-driven pumps and compressors.
Refurbishment
Replacement discs and wheels for turbine overhauls.
7. Inquiry Essentials
To quote your turbine disc or wheel, please provide the disc drawing with hub thickness, the required strength class, the applicable standard, and any bore inspection or balancing requirements.
