Evolution of precipitates in Ni-based wrought superalloys during hot working

Abstract:

During hot working, phase precipitation behavior is essential to deformed superalloys" tensile strength. This experiment tracked MC, M23C6, and γ′ precipitates of GH4738 superalloy at different stages during hot working. The behavior of precipitates in different stages of hot working: (1) The main precipitates in the superalloy billet were primary MC carbides and primary γ′. (2) After hot deformation, the primary MC carbides were partially decomposed and precipitated nano-sized intragranular secondary MC carbides and a small amount of grain boundary secondary M23C6 carbides and secondary γ′. (3) After heat treatment, the primary MC carbides were further decomposed until completely dissolved, and then the nanocrystalline secondary MC carbides were transformed into many bottle-shaped secondary M23C6 carbides. Meanwhile, γ′ was closed to complete precipitation, but γ′ the grew slightly.