Residual Stress Control for Superalloys Disk in Cooling Treatments

Abstract

The cooling method is a major factor in controlling residual stress, but also has significant influence on y' precipitation behavior and thereby mechanical performance. These effects of cooling rate make residual stress control a more complicated issue for superalloys. Residual stress evolution in a ^150mm 720Li disk during different cooling treatments has been studied by FEM simulation. XRD measurements and contour method were also carried out on the heat treated disk to verify the simulation predictions. Considering the influence of cooling type on residual stress and y' precipitation behavior, a special solid quenching treatment using induction heated dies as heat-transfer medium was introduced to relieve the residual stress and ensure the strength simultaneously.

Spinodal decomposition versus classical γ′ nucleation in a nickel-base superalloy powder: An in-situ neutron diffraction and atomic-scale analysis

“…Whilst unimodal microstructures created by rapid cooling offer desirable increases in yield strength over slower cooled samples [46], quenching is impractical for real manufacture of large components. Problems include the creation of high residual stresses [47], and transient thermal gradients and inhomogeneous microstructures [48].…”

Spinodal decomposition versus classical gamma-prime nucleation in a nickel-base superalloy powder: An in-situ neutron diffraction and atomic-scale analysis

“…Whilst unimodal microstructures created by rapid cooling offer desirable increases in yield strength over slower cooled samples [44], quenching is impractical for real manufacture of large components. Problems include the creation of high residual stresses [45], and transient thermal gradients and inhomogeneous microstructures [46]. The study here creates similarly desirable microstructures (in the 1000 • C sample, for example) directly from the powder without cooling related issues.…”