Welding Processes and Mechanical Properties of Inconel 718 Alloys

Inconel 718 is a precipitation-hardenable nickel–chromium–iron superalloy prized for its exceptional strength, corrosion resistance and stability at temperatures approaching 700 °C. It finds application in aero-engine components, industrial gas turbines and nuclear systems where weld integrity and long-term performance are critical. Common joining methods include gas tungsten arc welding (GTAW), laser beam welding (LBW), electron beam welding (EBW) and emerging hybrid or high-frequency-vibration-assisted techniques. Microstructural evolution in the fusion zone and heat-affected zone (HAZ) governs the formation of hard, brittle phases such as Laves and delta, which can impair ductility and fatigue life. Post-weld heat treatments are employed to re-precipitate γ′ and γ″ strengthening phases and to mitigate liquation and solidification cracking. Researchers are increasingly able to predict joint hardness and tensile properties from in-process temperature measurements, enabling real-time quality control. The broader challenge remains to tailor welding parameters and heat-treatment schedules to suppress deleterious phases, refine grain structure and ensure reproducible mechanical performance under cyclic loading, even in additive-manufactured or section-thin components.

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Welding Processes and Mechanical Properties of Inconel 718 Alloys publication trend

The graph below shows the total number of articles in welding processes and mechanical properties of inconel 718 alloys across all publications each year (not limited to Nature Index journals).

Technical terms

Heat-Affected Zone (HAZ): The region adjacent to the fusion boundary where thermal cycling alters the alloy’s microstructure without complete melting.

Fusion Zone (FZ): The area of base metal that has fully melted and resolidified during welding, often showing distinct grain structures.

Laves Phase: A brittle intermetallic compound rich in niobium that forms in interdendritic regions during rapid solidification.

γ′ and γ″ Precipitates: Metastable strengthening phases (Ni₃(Al,Ti) and Ni₃Nb respectively) that confer high temperature strength after ageing treatments.

Liquation Cracking: Cracking that occurs when low-melting-point phases at grain boundaries liquefy under thermal stress during welding.

References

1. Welding processes for Inconel 718- A brief review. IOP Conference Series Materials Science and Engineering (2018).
2. Temperature-Based Prediction of Joint Hardness in TIG Welding of Inconel 600, 625 and 718 Nickel Superalloys. Materials (2021).
3. Comparison of Hot Cracking Susceptibility of TIG and Laser Beam Welded Alloy 718 by Varestraint Testing. Metals (2019).
4. Study of Inconel 718 Welded by Bead-On-Plate Laser Welding under High-Frequency Micro-Vibration Condition. Metals (2019).