Excellent Structural Stability Udimet Alloy 520 Bars And Forgings For Aerospace

Alloy 520 (Udimet alloy 520) bars, forgings for aircraft and land based gas turbine blade etc.

1 PRODUCT

Alloy 520 (Udimet alloy 520) bars, forgings, sheets and bolts etc.

2 APPLICATION

Alloy 520 developed for use in the 1400-1700°F (760-927°C) temperature range, the alloy has excellent structural stability and unusually good fabricability. The primary application for alloy 520 is blading for aircraft and land-based gas turbines. And sheets and bolts for industrial and marine use.

3 OVERVIEW

Alloy 520 is a precipitation hardenable nickel base superalloy with an exceptional combination of high-temperature mechanical properties, corrosion resistance and forgeability characteristics.

4 CHEMICAL COMPOSITION (wt%):

5 PHYSICAL CONSTANTS

Density: 8.21 g/cm³ (0.297 lb/in³)

Melting range: 1260-1405°C (2300-2560°F)

6 MECHANICAL PROPERTY

1000 hours rupture strength of precipitation hardened Alloy 520

Fig. 1 Typical mechanical properties of precipitation-hardened Alloy 520.

7 HEAT TREATMENT

The conventional heat treatment for wrought Alloy 520 involves a three-step treatment consisting of 1121 °C/4 h/AC, 843 °C/24 h/AC, and 760 °C/16 h/AC (where each step is given by the temperature, the time at this tempera- ture, and the nature of the subsequent cooling, with AC indicating air cooling).

In some applications, a fourth stress relief step of 8 hours at 816 °C followed by air cooling is also employed.

8 METALLOGRAPHY
After the conventional heat treatments, Alloy 520 microstructure is composed of a Ni-Cr-Co (μ) rich matrix, which is hardened by fine (approximately 0.1-μm size) Ni₃(Al, Ti) gamma prime (μ') precipitates. Grain boundaries are decorated by M₂₃C₆ car- bides. Stringerlike primary MC carbides may also be present within the grains.

9 GRAIN GROWTH AND CARBIDE PRECIPITATION

(1) The grain coarsening behavior of Alloy 520 is controlled by the dissolution of primary MC carbides and M(C, N) carbonitrides. There are two distinct GCTs (grain coarsening temperatures) in this alloy corresponding to a MC solvus temperature slightly below 1190°C and a M(C, N) solvus temperature slightly below 1250°C.

(2) The grain boundary as well as the intragranular M₂₃C₆ carbide precipitate formed in this alloy over a temperature range of 600°C to 1050°C. Different stages of M₂₃C₆ precipitation kinetics led to different precipitate morphologies. The presence of discrete grain boundary carbides was observed at aging temperatures below 850°C, whereas a continuous network of grain boundary carbides resulted from higher aging temperatures. Intragranular M₂₃C₆ precipitates are strongly influenced by the dissolution of primary MC carbides in this alloy.

(3) A high solution treatment temperature induces intragranular M₂₃C₆ carbide precipitation upon aging due to increased dissolved carbon and to a reduced grain boundary area.

(4) Secondary MC carbide precipitation occurred in the range of 1100°C to 1177°C after solutionizing at a temperature equal to or greater than 1190°C. The MC carbide solvus temperature of Alloy 520 is close to 1190°C and M(C, N) carbonitrides dissolve above approximately 1250°C. No secondary MC carbides were observed in specimens solution treated below 1190°C. Therefore, primary MC carbide dissolution appears to be a precondition for the precipitation of secondary MC carbides in the alloy.

10 COMPETITIVE ADVANTAGE

(1) More than 50 years experience of research and develop in high temperature alloy, corrosion resistance alloy, precision alloy, refractory alloy, rare metal and precious metal material and products.
(2) 6 state key laboratories and calibration center.
(3) Patent technologies.

(4) High performance.

11 BUSINESS TERM