Table of Contents
Introduction
Inconel 939 (UNS N09939) is a nickel-based superalloy known for its high-temperature stability and resistance to oxidation. Designed to perform in extreme environments, this alloy supports applications in aerospace, power generation, and more. This guide provides a comprehensive look at Alloy 939, including its specifications, benefits, and practical uses in challenging industries.
What is Inconel 939?
Inconel 939 is a high-strength nickel-chromium alloy, enhanced with cobalt and molybdenum for durability in high-temperature settings. It retains strength and resists oxidation up to approximately 900°C (1652°F), making it ideal for demanding applications such as gas turbines and engine components. This alloy’s composition provides unique stability and resistance to cracking in thermal cycles, a critical advantage in industrial and aerospace uses.
What Are the Specifications of Inconel Alloy 939?
Inconel 939 Chemical Composition
| Element | Composition (%) |
| Nickel (Ni) | Balance |
| Chromium (Cr) | 19.0 – 23.0 |
| Cobalt (Co) | 18.0 – 20.0 |
| Titanium (Ti) | 3.0 – 4.5 |
| Aluminum (Al) | 1.0 – 3.0 |
| Tungsten (W) | 1.0 – 3.0 |
| Tantalum (Ta) | 1.0 – 1.8 |
| Niobium (Nb) | 0.5 – 1.5 |
| Molybdenum (Mo) | ≤ 0.5 |
| Zirconium (Zr) | ≤ 0.15 |
| Carbon (C) | ≤ 0.15 |
| Manganese (Mn) | ≤ 0.5 |
| Silicon (Si) | ≤ 0.5 |
| Sulfur (S) | ≤ 0.002 |
| Boron (B) | ≤ 0.015 |
939 Inconel Equivalent
| Specification | Equivalent |
| UNS | N09939 |
| ASTM | B637 |
| AMS | 5666 |
| DIN | W.Nr. 2.4856 |
| EN | 2.4856 |
| JIS | NCF 939 |
Inconel Metal 939 Mechanical Properties
| Property | Value |
| Tensile Strength | 965 MPa (140,000 psi) |
| Yield Strength | 725 MPa (105,000 psi) |
| Creep Strength | 206 MPa (30,000 psi) at 1,000°C |
| Fatigue Strength | 300 MPa |
| Elongation | 15% |
| Hardness | 35 HRC |
Inconel Metal 939 Physical Properties
| Property | Value |
| Density | 8.44 g/cm³ |
| Melting Point | 1,330°C (2,426°F) |
| Thermal Expansion | 12.9 µm/m°C (20–1000°C) |
| Thermal Conductivity | 11.2 W/m·K at 20°C |
| Electrical Resistivity | 1.29 µΩ·m at 20°C |
Nickel Alloy 939 Corrosion Resistance
| Corrosive Environment | Resistance |
| Oxidation (Air, 980°C) | Minimal oxidation over long-term exposure |
| Carburization | High resistance up to 1,000°C |
| Sulfidation (H2S Environment) | Excellent resistance up to 900°C |
| Chloride SCC | Resistant in non-stagnant chloride environments |
| Aqueous Corrosion (pH 7) | Moderate resistance |
939 Inconel Heat Treatment
| Process | Temperature |
| Solution Annealing | 1,100°C (2,012°F) |
| Aging | 870°C (1,600°F) |
For additional information on recent research and methodologies for heat-treating L-PBF (Laser Powder Bed Fusion) 939 Inconel, refer to the NASA Heat Treatment Study on L-PBF Inconel 939 (July 2023).
How Does Inconel Alloy 939 Benefit You?
Inconel 939 offers clear advantages:
- High Heat Resistance: Handles extreme temperatures, ideal for turbines and engines.
- Corrosion and Oxidation Resistance: Essential in harsh, high-heat environments.
- Fatigue and Creep Strength: Withstands continuous, high-stress use.
- Durability: Designed for long-lasting performance with minimal maintenance.
What is Inconel 939 Used For?
Inconel 939 finds its place in applications that demand durability and stability under intense conditions, such as:
- Aerospace: Used in turbine blades, combustors, and exhaust liners.
- Power Generation: Components for gas turbines, heat shields, and thermal protection.
- Automotive: Engine parts that endure high temperatures and stress.
- Industrial Equipment: Furnace hardware and heat exchangers for extreme environments.
How Does Inconel Alloy 939 Compare to Other Alloys?
Inconel 939 vs Inconel 718
While both offer excellent performance, Inconel 939 is better suited for higher temperatures due to its enhanced oxidation resistance. Inconel 718 is durable but performs best in slightly lower temperature ranges.
Inconel 939 vs. Inconel 625
Inconel 939’s high-temperature stability and creep resistance make it ideal for extreme conditions, whereas Inconel 625 excels in applications requiring exceptional corrosion resistance at moderate temperatures.
Conclusion
Inconel 939 is a top choice for industries requiring strength and reliability in high-heat, high-stress environments. With superior oxidation and corrosion resistance, this alloy ensures lasting performance, reducing the need for frequent maintenance. If you need an alloy that can handle extreme conditions, 939 Inconel is built to deliver.
Read More:
What is Inconel 617 (UNS N06617)?