The Effect of Vacuum Arc Remelting of Airmelt Electrodes on the Structure and Elevated Temperature Properties of a Nickel-Base Gas Turbine Superalloy

Abstract

Vacuum arc remelting of electrodes prepared by the vacuum induction melting process is currently being used to provide high integrity forging billet stock of complex nickel-base superalloys. The purpose of this investigation was to study the effect of vacuum arc remelting of airmelt electrodes on the structure and properties of a popular nickel-base gas turbine superalloy—M-252. A secondary purpose was to study the effect of solution temperature on carbide banding, grain size, and properties of the resulting material. The results indicate that the use of airmelt electrodes is feasible for this particular alloy and probably for other gas turbine superalloys of a similar chemistry. The effects of forging temperature on carbide solution and grain growth are similar to those previously noted in vacuum induction melted product. A differential grain size effect, apparently related to the straightening operation used to produce the bar stock, was found to have a significant effect on the rupture and elevated temperature tensile properties.