Melting of Superalloys
SourceMelting of superalloys is the initial, and perhaps most important, step in the production of materials used in critical high-temperature applications. Increasing demand for high-quality superalloys with specific characteristics has resulted in various combinations of primary, melting, refining, and secondary remelting operations. Specific characteristics of each of these process operations are used to produce superalloys that meet customer quality requirements for (1) chemistry, (2) product form, and (3) structural uniformity.
Various combinations of melting processes can be used to obtain a desired primary chemistry not only in terms of the primary elements, but also for residual and tramp elements. Product forms frequently dictate a combination of melting processes that give importance to the shape of ingots, the end product of superalloy melting processes. Additionally, it is frequently important to choose melting combinations that achieve ingot structure control for optimum primary phase distribution, cleanliness or hot workability, or both.