IN713LC Superalloy Equiaxed Crystal Casting Turbine Blades

Core Technology of IN713LC Equiaxed Crystal Casting

1. Wax Pattern Production Injection-molded wax patterns are fabricated with ±0.05 mm tolerances to replicate detailed airfoil geometries and cooling structures.

2. Ceramic Shell Construction Multiple ceramic layers are applied to the wax pattern, forming a robust 6–8 mm mold suitable for high-temperature alloy casting.

3. Dewaxing and Shell Firing Autoclave dewaxing at 150°C removes wax patterns, followed by shell sintering at 1000–1100°C for structural strength.

4. Vacuum Induction Melting IN713LC alloy is melted under high vacuum (≤10⁻³ Pa) using vacuum induction melting, ensuring purity and uniform chemistry.

5. Equiaxed Solidification The molten alloy is poured into preheated shells and solidified under controlled conditions to produce fine equiaxed grains (0.5–2 mm).

6. Shell Removal and Cleaning After cooling, ceramic shells are removed using blasting, preserving intricate blade surfaces and cooling features.

7. Heat Treatment Solution treatment at 1200°C and aging at 850°C enhance the γ' phase strength through thermal processing.

8. Inspection and Finishing Parts are machined and finished using superalloy CNC machining and inspected via CMM and X-ray to ensure quality compliance.

IN713LC Material Properties for Equiaxed Turbine Blades

• Maximum Operating Temperature: 982°C (1800°F)

• Ultimate Tensile Strength: ≥1034 MPa

• Yield Strength: ≥862 MPa

• Creep Rupture Strength: ≥200 MPa at 760°C for 1000 hours

• Elongation: ≥5%

• Oxidation Resistance: Excellent under cyclic thermal loading

• Grain Size (ASTM): 5–7 across entire blade section

Case Study: IN713LC Equiaxed Blade Production for Gas Turbine

Project Background

A global power turbine OEM selected Neway AeroTech to produce IN713LC first-stage turbine blades using equiaxed crystal casting for a 60 MW industrial gas turbine. The project required tight dimensional tolerances, high mechanical consistency, and thermal fatigue durability under continuous 950°C operation.

Applications

• Industrial Gas Turbine Blades (e.g., GE Frame 6B): Used in power plants requiring long-term thermal and mechanical reliability.

• Aerospace Turboprop Engines (e.g., PW100): Blades subjected to cyclic temperature loads and aggressive oxidation environments.

• APUs and Helicopter Engines: Compact blade profiles demanding lightweight, creep-resistant materials.

• Naval Gas Turbines (e.g., LM2500): Corrosion-resistant blades needed for marine propulsion systems.

Manufacturing Process for IN713LC Equiaxed Blades

1. Wax Assembly Engineering Blade profile and gating designed with support from CFD analysis to ensure smooth metal flow and grain uniformity.

2. Precision Shell Construction and Vacuum Casting IN713LC is cast under vacuum conditions with preheated molds, ensuring fine equiaxed grain formation and minimal segregation.

3. Post-Casting Heat Treatment Heat treatment stabilizes the γ' phase, increasing creep resistance and dimensional stability.

4. CNC and EDM Finishing Final dimensions are achieved via CNC machining and EDM, particularly for internal cooling channels and fir-tree roots.

5. Inspection and Qualification Metallographic analysis, X-ray, and CMM validation ensure each blade meets dimensional and structural specifications.

Core Challenges in Equiaxed Blade Casting

• Achieving uniform grain structure in complex airfoil profiles

• Preventing microsegregation during solidification

• Maintaining precision across thin trailing edges and cooling holes

• Ensuring oxidation resistance during prolonged high-cycle fatigue exposure

Results and Verification

• ASTM grain size of 6–7 confirmed across full blade span

• Zero internal porosity post-casting verified via X-ray

• Mechanical properties exceeded 1034 MPa tensile and 200 MPa creep benchmarks

• Dimensional tolerances within ±0.03 mm maintained after CNC finishing

• 100% NDT compliance across production batch

FAQs

1. What are the advantages of equiaxed casting for turbine blades?

2. How does IN713LC compare to other superalloys in blade applications?

3. What post-processing is required after equiaxed casting?

4. How do you ensure grain size consistency across the blade?

5. What industries most commonly use IN713LC equiaxed blades?