Morphology and microstructure evolution of δ phase during cross wedge rolling of GH4169 alloy

Abstract

Optical microscope (OM) and electron backscatter diffraction (EBSD) were applied to observe the constant section shrinkage phase morphology and microstructure of the cross wedge rolling GH4169 superalloy under solid solution state. The phase morphology evolution and the microstructure impact during cross wedge rolling was studied. The results show that the δphase gradually bends, twists and cuts under the rolling force so that it changes from acicula to short rod or granule. With the increase of the section shrinkage, the spheroidization degree increases and the dynamic recrystallization of GH4169 alloy during cross wedge rolling is promoted by the existence of the δphase. The pinning effect of the relative grain boundaries inhibits the growth of the dynamic recrystallized grains and the average grain size of aged specimen is 2.84μm with 50% cross section shrinkage, while the average grain size of the solid solution specimen is 25.3μm.