Cast Superalloys

Date: 2026年4月20日 Categories: News Views: 55

Cast superalloys are high-end special high-temperature structural materials formed directly via vacuum melting and precision casting. Without extensive subsequent plastic deformation processing, they feature the highest alloying degree and optimal high-temperature creep and stress-rupture properties among all superalloy categories.

Overview

Cast superalloys are produced by remelting master alloys in vacuum furnaces and casting into near-net-shape components. Since their design does not require favorable deformability, high contents of alloying elements are allowed. The total proportion of solid-solution and precipitation-strengthening elements can exceed 40 wt%.

Strengthened by solid-solution hardening, γ′/γ″ intermetallic precipitation hardening, and grain boundary strengthening elements (C, B, Zr, Hf), the alloys maintain excellent high-temperature strength, creep resistance, microstructural stability and hot corrosion resistance under 600–1200℃ oxidative and corrosive working conditions with complex cyclic stress.

Classification by Microstructure & Casting Technology

  1. Equiaxed Grain Cast Superalloys (K-series)

    Mature conventional precision casting process with uniform equiaxed grains. Cost-effective, widely used for stationary components including casings, diffusers and guide vanes. Typical grades: K403, K418, K4169.

  2. Directionally Solidified (DS) Columnar Grain Alloys (DZ-series)

    Unidirectional columnar grain structure eliminates transverse grain boundaries, greatly improving high-temperature fatigue and creep resistance. Ideal for turbine working blades. Typical grades: DZ125, DZ404.

  3. Single Crystal (SX) Superalloys (DD-series)

    Completely free of grain boundaries, representing the highest-temperature grade superalloys with superior strength, thermal fatigue resistance and service life. Mainly applied to premium aero-engine turbine blades. Typical grades: DD5, DD6, DD406.

Matrix Classification

  • Nickel-based cast superalloys: Dominant mainstream alloys with Ni matrix over 50 wt%. Alloyed with Cr, Co, W, Mo, Ta, Al, Ti, serving at 650–1150℃ with balanced comprehensive performance.
  • Cobalt-based cast superalloys: Higher melting point, outstanding hot corrosion and thermal fatigue resistance, mainly for combustor components.
  • Iron-based cast superalloys: Low-cost alloys for medium-low temperature heat-resistant structural parts.

Key Properties

Excellent high-temperature stress rupture strength and creep resistance; superior oxidation and hot gas corrosion resistance; stable as-cast microstructure; capable of forming complex precision castings with near-net shape via investment casting, minimizing post-machining.

Applications

Hot-end components of aero-engines; turbine blades and nozzles of industrial gas turbines; power generation equipment; high-temperature pressure components in petrochemical industry; special high-temperature valves and turbomachinery parts.
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