Inconel 713LC
Introduction to Inconel 713LC
Inconel 713LC is a low-carbon, cast nickel-chromium superalloy developed for superior strength, oxidation resistance, and fatigue life at elevated temperatures up to 980°C (1800°F). It is a modified version of Inconel 713C with reduced carbon content and improved castability, which makes it especially suitable for high-integrity aerospace turbine blades, vanes, and structural hot section components.
The alloy maintains a base composition of nickel (~75%) and incorporates chromium (12–14%), aluminum (5.5–6.5%), molybdenum (4–5%), and niobium (1.5–2.5%). With enhanced resistance to shrinkage cracking, Inconel 713LC offers reliable structural integrity and consistent mechanical properties in thin-walled, investment-cast designs that often require CNC machining to meet precision tolerances.
Chemical, Physical, and Mechanical Properties of Inconel 713LC
Inconel 713LC (UNS N07713 / AMS 5382) is typically supplied in investment cast and aged condition, meeting the performance needs of aerospace and power generation components.
Chemical Composition (AMS 5382)
Element | Composition Range (wt.%) | Key Role |
|---|---|---|
Nickel (Ni) | Balance (~75.0%) | Base alloy for high-temperature strength |
Chromium (Cr) | 12.0–14.0 | Enhances oxidation resistance |
Aluminum (Al) | 5.5–6.5 | Forms γ′ phase for high-temperature strength |
Molybdenum (Mo) | 4.0–5.0 | Improves creep rupture properties |
Niobium (Nb) | 1.5–2.5 | Carbide and intermetallic strengthening |
Titanium (Ti) | 0.6–1.2 | Stabilizes γ′ structure |
Carbon (C) | 0.02–0.06 | Reduced content for better weldability and castability |
Zirconium (Zr) | 0.05–0.15 | Increases grain boundary strength |
Boron (B) | 0.005–0.015 | Improves hot strength and ductility |
Iron (Fe) | ≤3.0 | Residual element |
Silicon (Si) | ≤0.50 | Controls oxidation scaling |
Manganese (Mn) | ≤0.50 | Enhances castability |
Physical Properties
Property | Value (Typical) | Test Standard/Condition |
|---|---|---|
Density | 8.00 g/cm³ | ASTM B311 |
Melting Range | 1250–1330°C | ASTM E1268 |
Thermal Conductivity | 11.3 W/m·K at 100°C | ASTM E1225 |
Electrical Resistivity | 1.21 µΩ·m at 20°C | ASTM B193 |
Thermal Expansion | 13.8 µm/m·°C (20–1000°C) | ASTM E228 |
Specific Heat Capacity | 458 J/kg·K at 20°C | ASTM E1269 |
Elastic Modulus | 196 GPa at 20°C | ASTM E111 |
Mechanical Properties (Aged Cast Condition)
Property | Value (Typical) | Test Standard |
|---|---|---|
Tensile Strength | 930–1050 MPa | ASTM E8/E8M |
Yield Strength (0.2%) | 600–730 MPa | ASTM E8/E8M |
Elongation | ≥4–6% (25mm gauge) | ASTM E8/E8M |
Hardness | 320–380 HB | ASTM E10 |
Creep Rupture Strength | ≥160 MPa @ 871°C, 100h | ASTM E139 |
Key Characteristics of Inconel 713LC
High-Temperature Performance: Maintains structural integrity above 950°C with sustained creep rupture strength above 160 MPa, making it suitable for long-cycle turbine operation.
Superior Castability: Low carbon and Zr/B micro-alloying reduce hot tearing and shrinkage porosity during solidification, enabling more precise and complex investment casting.
Thermal Fatigue and Oxidation Resistance: High Cr and Al content forms Cr₂O₃ and Al₂O₃ protective layers, providing oxidation protection in dynamic engine environments.
CNC Machinability: Post-casting machining supports finishing tolerances down to ±0.02 mm and surface roughness Ra ≤ 0.8 µm using optimized cutting parameters and tool systems.
CNC Machining Challenges and Solutions for Inconel 713LC
Machining Challenges
Material Hardness and Wear
Cast-aged 713LC exhibits hardness up to 380 HB, challenging cutting tool integrity during prolonged operations.
Brittle Behavior
With elongation of ~4–6%, sudden tool impacts or incorrect feed rates may cause microcracking or chipping.
Heat Concentration
Thermal conductivity remains low (<12 W/m·K), increasing tool nose temperatures and promoting crater wear under dry or low-coolant conditions.
Optimized Machining Strategies
Tool Selection
Parameter | Recommendation | Rationale |
|---|---|---|
Tool Material | Ceramic (SiAlON) or CBN for finishing | High red hardness and thermal resistance |
Coating | TiAlN/AlCrN, 3–6 µm via PVD | Enhances oxidation and wear resistance |
Geometry | Positive rake (10–12°), chamfered edge | Prevents edge chipping and improves finish |
Cutting Parameters (ISO 3685)
Operation | Speed (m/min) | Feed (mm/rev) | DOC (mm) | Coolant Pressure (bar) |
|---|---|---|---|---|
Roughing | 15–25 | 0.20–0.30 | 2.0–3.0 | 80–120 |
Finishing | 30–45 | 0.05–0.10 | 0.3–0.8 | 100–150 |
Surface Treatment for Machined Inconel 713LC Parts
Hot Isostatic Pressing (HIP)
HIP densifies cast microstructures under 100–200 MPa pressure and >1100°C temperature, removing internal porosity and increasing fatigue resistance by over 25%.
Heat Treatment
Heat Treatment includes solution annealing at 1160°C and aging at 845°C to enhance γ′ stability and mechanical uniformity.
Superalloy Welding
Superalloy Welding using preheated TIG or EB welding with Ni-Cr filler metals preserves weld strength and resists microfissuring.
Thermal Barrier Coating (TBC)
TBC Coating applies 150–300 µm YSZ ceramics to extend thermal fatigue life and reduce surface temperatures by 150–200°C.
Electrical Discharge Machining (EDM)
EDM enables precise formation of blade roots, cooling passages, and fir-tree slots to ±0.01 mm tolerances.
Deep Hole Drilling
Deep Hole Drilling delivers L/D ≥ 40:1 bore accuracy for cast turbine cooling channels and combustor parts.
Material Testing and Analysis
Material Testing includes ultrasonic, X-ray, and grain structure inspection per AMS 2175 and ASTM E112, ensuring dimensional and metallurgical compliance.
Industry Applications of Inconel 713LC Components
Aerospace Turbines
Turbine blades, nozzle vanes, and hot section castings.
Withstands high centrifugal loads and oxidation cycles.
Power Generation
Stationary and rotating blades, shrouds, and nozzle guides.
Excellent long-term mechanical performance at 900–980°C.
Gas Compression and Turbocharging
Exhaust manifolds, turbo rotors, and turbine housings.
Reliable under rapid thermal shock and high-speed rotation.
Industrial Combustion Systems
Burners, combustion chambers, and heat shields.
Maintains structural integrity under prolonged thermal exposure.
FAQs
What is the difference between Inconel 713LC and 713C in mechanical and castability performance?
Which cutting parameters optimize tool life for CNC machining Inconel 713LC?
Is HIP treatment necessary for aerospace-grade Inconel 713LC components?
Can Neway perform full in-house machining, welding, and TBC application for Inconel 713LC?
What testing standards apply for qualifying Inconel 713LC cast parts in aerospace or power generation?
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