Udimet 720 / 720Li Forgings — Gamma-Prime Strengthened Nickel Superalloy for the Highest-Temperature Turbine Disc Applications Beyond Inconel 718
Shivam Forge manufactures forgings in Udimet 720 and 720Li — a high gamma-prime-fraction nickel-based superalloy engineered for gas turbine disc applications that operate above the practical temperature ceiling of Inconel 718 — for compressor and turbine disc forgings in aerospace and industrial gas turbine programmes requiring strength retention beyond 700°C. Rajkot, India. Call +91-9265772827.
Inconel 718 dominates gas turbine disc applications because gamma-double-prime (Ni3Nb) precipitation delivers high strength combined with genuinely useful fabricability — but that same gamma-double-prime phase has a metallurgical ceiling: above approximately 700°C, it begins transforming into the incoherent, non-strengthening delta phase, and 718's strength advantage erodes as service temperature climbs past this point. Udimet 720 and its low-carbon, low-boron variant 720Li were developed specifically to serve turbine disc applications sitting above that ceiling, where higher-pressure-ratio, higher-efficiency engine cycles push compressor discharge and turbine inlet-adjacent temperatures beyond what 718 can reliably serve. The alloy achieves this through a fundamentally different strengthening approach: rather than relying primarily on gamma-double-prime, Udimet 720 is strengthened by a substantially higher volume fraction of gamma-prime (Ni3(Al,Ti,Ta)) — commonly in the 40–45% range, well above 718's gamma-prime content — combined with solid-solution strengthening from molybdenum and tungsten. This higher gamma-prime fraction is stable to meaningfully higher temperatures than 718's gamma-double-prime-dominant structure, extending useful strength retention further into the elevated-temperature range modern high-pressure-ratio engine architectures demand. The trade-off is forgeability: a higher gamma-prime volume fraction that resists dissolving at forging temperature makes the alloy inherently more resistant to deformation and more prone to cracking if forging parameters aren't tightly controlled, which is why Udimet 720/720Li forging typically demands narrower temperature windows, slower strain rates, and — for the most demanding disc applications — powder-metallurgy billet conversion or isothermal forging practice that 718 rarely requires. Within the superalloy disc family, this is the honest trade Udimet 720 represents: meaningfully higher temperature capability than 718, purchased at the cost of a more demanding, less forgiving manufacturing process.
Forged Udimet 720/720Li disc blanks for high-pressure turbine and compressor disc applications operating above the temperature range where Inconel 718's gamma-double-prime strengthening begins losing effectiveness.
Forged disc components for higher-pressure-ratio, higher-efficiency gas turbine engine architectures where compressor discharge temperatures exceed what standard 718-grade disc material reliably serves.
Forged Udimet 720 disc blanks for industrial and power-generation gas turbine applications requiring the alloy's elevated-temperature strength retention beyond typical 718 service limits.
Forged shaft and rotating structural components in Udimet 720 where the combination of high strength and elevated-temperature capability the alloy's gamma-prime strengthening provides is the design requirement.
Forging performed within Udimet 720's characteristically narrow temperature window, reflecting the alloy's high gamma-prime volume fraction and correspondingly reduced forgeability compared to gamma-double-prime-dominant alloys like 718.
Forging strain rate controlled to manage the deformation resistance a high gamma-prime fraction creates, reducing the risk of cracking that comes with pushing this alloy family through standard hot-forging parameters.
Solution heat treatment and controlled multi-step aging cycle developing the gamma-prime precipitate size distribution that determines Udimet 720's final strength, elevated-temperature capability, and fatigue performance.
Positive material identification confirming chemistry against the Udimet 720 or 720Li specification, combined with mechanical property and grain size verification per applicable AMS or customer specification, and EN 10204 3.1/3.2 certification.
The gas turbine disc superalloy family exists because no single nickel-based alloy covers the full range of temperature and strength requirements modern engine architectures demand across every disc location in a compressor and turbine section. Inconel 718 covers the largest share of that range extremely well, combining high strength with genuinely practical fabricability, but its gamma-double-prime strengthening mechanism has a defined temperature ceiling — above roughly 700°C, the phase that gives 718 its strength begins converting to a form that no longer contributes meaningfully to mechanical properties. Engine architectures that push compressor discharge temperatures, or disc locations positioned closer to the hot section, past that ceiling need a different alloy, and Udimet 720 was developed specifically to fill that role.
The metallurgical distinction is straightforward once you understand what each alloy leans on for strength. 718 relies primarily on gamma-double-prime (Ni3Nb) precipitation, a strengthening mechanism that develops rapidly and delivers excellent room-and-moderate-temperature properties but loses its advantage as temperature climbs. Udimet 720 instead relies on a much higher volume fraction of gamma-prime (Ni3(Al,Ti,Ta)) — routinely 40–45% of the microstructure by volume, supplemented by solid-solution strengthening from molybdenum and tungsten — and this gamma-prime-dominant structure remains stable and effective at meaningfully higher temperatures than 718's gamma-double-prime-dominant structure. This is why Udimet 720 occupies the higher-temperature tier within the superalloy disc family: it isn't simply a stronger version of 718, it's a differently engineered alloy solving for a different point on the temperature-versus-strength curve.
That higher gamma-prime fraction is also exactly what makes Udimet 720 a more demanding forging job than 718. A microstructure with a large volume fraction of hard, stable precipitate resists plastic deformation more than a microstructure where the strengthening phase dissolves more readily at forging temperature, which translates directly into a narrower acceptable forging temperature window, more carefully controlled strain rates, and a higher risk of cracking if process parameters drift outside the established envelope. For the most demanding aerospace disc applications, this often extends to specifying powder-metallurgy billet conversion, which produces a finer, more uniform starting grain structure than conventional cast-and-wrought billet and gives the forging process more margin to work within. None of this makes Udimet 720 impractical to forge — it's a well-established, qualified aerospace alloy — but it does mean the manufacturing process demands a level of temperature and strain-rate discipline that 718 is comparatively more forgiving about.
For gas turbine engine OEMs and aerospace Tier 1 suppliers sourcing forged Udimet 720 or 720Li disc components for high-temperature turbine and compressor applications beyond Inconel 718's practical service range, Shivam Forge manufactures with controlled forging temperature and strain rate practice matched to this alloy's demands. Contact our engineering team at +91-9265772827 or sales@shivamforge.com with your drawing and specification for a manufacturability review and quotation.
718's gamma-double-prime strengthening phase begins transforming to non-strengthening delta phase above approximately 700°C, capping its useful high-temperature strength retention. Udimet 720's higher gamma-prime volume fraction (typically 40–45%, versus 718's much lower gamma-prime content) remains stable to meaningfully higher temperatures, making it the appropriate choice for turbine disc locations operating above 718's practical temperature ceiling.
720Li is a low-carbon, low-boron variant of standard Udimet 720, developed to improve forgeability, reduce the risk of certain grain-boundary carbide and boride issues, and improve fatigue crack propagation resistance. 720Li is the more commonly specified variant for critical rotating aerospace disc applications; standard 720 remains used where its specific property balance is preferred.
718's strengthening gamma-double-prime phase dissolves relatively readily at forging temperature, giving the alloy a comparatively wide, forgiving forging window. Udimet 720's much higher gamma-prime fraction resists dissolving as completely, increasing deformation resistance and cracking risk unless forging temperature and strain rate are tightly controlled within a narrower window than 718 requires.
Both routes exist depending on the application's demands. The most critical, highest-performance disc applications often specify powder-metallurgy billet conversion for the finer, more uniform grain structure it provides, while less extreme applications can use cast-and-wrought billet with correspondingly controlled forging practice. We can discuss which billet route fits your application and specification during quotation.
PMI verification confirming chemistry against the specific Udimet 720 or 720Li specification, mechanical property and grain size testing per applicable AMS or customer-specified requirements, and EN 10204 3.1/3.2 material test certification with full traceability, matching the documentation rigor aerospace gas turbine disc programmes require.
Why Choose Shivam Forge
Shivam Forge delivers precision hot-forged components from our integrated Shapar, Rajkot facility — covering forging, CNC machining, heat treatment, and quality inspection under one roof.
