Method for reducing abnormal grain growth in Ni-base superalloys

摘要

A method of forging Ni-base superalloys is described which avoids the growth of abnormally large grains in the surface region of a forged article. The method involves forging and/or annealing a Ni-base superalloy in a carburizing environment. Forging and/or annealing in a carburizing environment is done to maintain the carbon concentration in the surface region at a level that is sufficient to prevent the depletion of carbides and carbonitrides. The carburizing environment may also be selected so that it is non-oxidizing with respect to aluminum, in order to prevent the depletion of aluminum and the reduction of the &ggr;' phase in the surface region.