TMS-138 Single Crystal Casting Power Generation Turbine Discs Workshop
Introduction
TMS-138 is a fourth-generation single-crystal nickel-based superalloy developed for ultra-high-temperature turbine components. It provides superior creep rupture strength, oxidation resistance, and phase stability up to 1200°C, making it ideal for advanced turbine disc applications. At our dedicated single crystal casting workshop, we manufacture precision TMS-138 turbine discs for power generation gas turbines, delivering dimensional tolerances within ±0.05 mm, controlled [001] orientation, and porosity below 1%.
Our TMS-138 disc castings are engineered for demanding base-load and peaking turbine stages that operate under extreme centrifugal, thermal, and fatigue loads.
Core Technology: Single Crystal Casting of TMS-138
We use vacuum directional solidification in a Bridgman furnace to cast TMS-138 turbine discs with controlled [001] crystal orientation. The alloy is vacuum melted at ~1460°C and poured into ceramic shell molds preheated to ~1100°C. Withdrawal rates of 1–3 mm/min are maintained to produce single-crystal grain structures free from grain boundaries, enhancing long-term creep and fatigue life under continuous high-stress turbine operation.
Material Characteristics of TMS-138 Alloy
TMS-138 is a fourth-generation SX superalloy developed by the National Institute for Materials Science (NIMS), Japan. It features a high γ′ volume fraction and significant rhenium content for creep resistance and phase stability. Key properties include:
Property | Value |
|---|---|
Density | ~9.0 g/cm³ |
Ultimate Tensile Strength (at 1100°C) | ≥1200 MPa |
Creep Rupture Strength (1000h @ 1100°C) | ≥220 MPa |
Operating Temperature Limit | Up to 1200°C |
Oxidation Resistance | Excellent |
Grain Structure | Single Crystal [001] |
These properties make TMS-138 one of the most advanced materials for turbine disc applications in ultra-efficient gas turbine engines.
Case Study: TMS-138 Turbine Disc Production
Project Background
A next-generation combined-cycle power plant project required high-strength, creep-resistant turbine discs capable of operating at 1150–1200°C under high rotational stress. TMS-138 was selected for its fourth-generation performance characteristics. We manufactured single-crystal turbine discs with full [001] orientation, HIP consolidation, and final machining to meet ISO 19443 and ASME Section III standards for rotating machinery.
Typical Power Generation Applications
High-Pressure Turbine Discs (e.g., Siemens HL-Class, GE HA-Class): TMS-138 discs deliver exceptional strength and oxidation resistance in the most demanding turbine stages.
Second-Stage SX Rotor Discs: Single-crystal discs in the secondary turbine section provide extended creep life and dimensional stability under heavy loading cycles.
Transition Coupling Discs: Critical rotating structures connecting hot gas sections to cold compressor stages, requiring unmatched fatigue and phase stability.
Advanced Cycle Rotor Discs: Components designed for supercritical CO₂ or closed-loop Brayton cycle systems, where thermal fatigue and oxidation control are paramount.
These applications highlight TMS-138’s role in maximizing turbine output, lifecycle, and heat-to-power efficiency under extreme thermal and mechanical conditions.
Manufacturing Solutions for TMS-138 Turbine Discs
Casting Process Wax assemblies are built to precise geometries and invested in ceramic shell molds. Vacuum melting at ~1460°C and Bridgman directional solidification produce [001]-oriented single-crystal discs. Cooling profiles are optimized to eliminate stray grains and ensure defect-free structure across disc hubs and outer rims.
Post-processing Hot Isostatic Pressing (HIP) at 1190°C and 100 MPa is applied to densify the casting and eliminate any residual porosity. Post-HIP solution and aging heat treatments optimize γ′ distribution and microstructural uniformity.
Post Machining CNC machining ensures tight tolerances on bore diameters, bolt circles, and aerodynamic profiles. EDM enables fine-feature shaping, and deep hole drilling is performed for internal stress relief or cooling holes.
Surface Treatment Thermal barrier coatings (TBC) such as YSZ are applied to disc faces to reduce thermal loads and oxidation scaling. Diffusion aluminide or platinum-aluminide coatings are available for additional corrosion protection.
Testing and Inspection Each disc undergoes X-ray nondestructive testing, CMM dimensional verification, creep and tensile testing, and metallographic analysis to confirm grain orientation, γ′ morphology, and casting integrity.
Core Manufacturing Challenges
Ensuring single-crystal [001] orientation throughout large-diameter turbine discs.
Preventing stray grain formation and thermal distortion during directional solidification.
Maintaining mechanical consistency across complex hub and rim geometries.
Achieving low-cycle fatigue resistance and oxidation control in continuous high-load service.
Results and Verification
Single-crystal integrity verified via Laue X-ray diffraction and SEM imaging.
Porosity <1% confirmed post-HIP through radiographic and density testing.
Creep rupture ≥220 MPa at 1100°C validated by 1000-hour test cycles.
Dimensional tolerance within ±0.05 mm confirmed via multi-axis CMM scanning.
No γ′ coarsening or surface scaling after 1000 thermal fatigue cycles at 1200°C.
FAQs
Why is TMS-138 ideal for single-crystal turbine disc casting in power generation?
How is directional solidification controlled during TMS-138 casting?
What surface treatments are compatible with TMS-138 to enhance oxidation resistance?
Can TMS-138 discs be adapted for hybrid or advanced cycle turbine platforms?
What quality certifications and testing procedures support compliance in critical rotating components?
