Supergravity-Induced Separation of Oxide and Nitride Inclusions from Inconel 718 Superalloy Melt

Abstract

Herein, a method of supergravity-enhanced separation was used to remove oxide and nitride inclusions from Inconel 718 superalloy melt, with elucidating the inclusion removal behavior by varying the gravity coefficients (G) and separation times (t) used for melt treatment. Under supergravity conditions, inclusions concentrated at the sample top and are almost absent at the sample bottom. Moreover, the inclusion number density and average size showed a gradient distribution along the supergravity direction, and the steepness of this gradient rapidly increased with increasing G and t. The experimentally determined inclusion movement velocities agreed well with those calculated using Stokes’s law at G ≤ 210 and t ≤ 10 min. At G = 210 and t = 10 min, the total oxygen and nitrogen contents of the sample decreased from 34.4 to 8.7 ppm and 133.4 to 34.1 ppm, respectively, corresponding to oxide and nitride removal efficiencies of 74.7% and 74.4%, respectively.