Influence of thermo-mechanical treatment on the precipitation strengthening behavior of Inconel 740, a Ni-based superalloy

In this work, we have systematically explored the influence of thermo-mechanical treatment on the precipitation behavior and its strengthening in Inconel 740, a relatively new Ni-based superalloy, using specimens on which different levels of stresses were applied at 700 degrees C. With increasing applied stress, fraction of gamma prime precipitates increased (without significant size change) and nanoindentation hardness was enhanced. The stress effects were discussed in terms of the free energy barrier for heterogeneous nucleation and the prevailing mechanisms of precipitation strengthening.