There appears to be a general misconception among some superalloy users relative to the refining capabilities of the vacuum induction melting (VIM) process. Some apparently feel the process is incapable of providing "clean" superalloy product and have attempted to force suppliers to incorporate the use of ceramic foam filters within their respective processes and/or have specified the use of secondary refining processes such as electron beam cold hearth refining (EBCHR).

The VIM process misconceptions appear to result from a general lack of understanding of the process. Exacerbating such misconception is the increasing amount of product in the marketplace coming from a segment of the superalloy producing industry which appears to have abandoned its commitment to excellence.

The quality of superalloy product is in direct proportion to the respective producers commitment to excellence. Extremely clean superalloys can be produced in optimized and well maintained VIM processes. Non-filtered and non-EBCHR processed VIM alloy product originating at "committed" producers are successfully used in some of the most demanding blade and vane component casting applications in existence.

This narrative attempts to set the record straight. It therefore illustrates how "committed" producers operate VIM processes, highlights some of the important VIM process variables requiring constant scrutiny, and sets forth examples of quality levels achieved for various polycrystalline, DS columnar grained and DS single crystal casting superalloys. Furthermore, superalloy quality measurement techniques are discussed, the relative merits of ceramic foam filter usage in the production VIM process are addressed, and limited EBCHR experiences are described.