Grain refinement of Fe-32%Ni alloy by multi-axial forging

The effect of strain on the microstructure evolution of Fe-32%Ni alloy during multi-axial forging at the temperature of 500°C and a strain rate of 2×10 s was investigated by optical microscope (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron back scatter diffraction (EBSD) observations. The results show that the austenite grains were greatly refined with increasing cumulative strain, and the microstructure evolution during multi-axial forging can be summarized as such a process that deformation bands crossing each other subdivide the original austenite grain into several sub-grains and then these sub-grains are subdivided into more small ones and gradually angled to new independent grains with their boundaries transformed into large angle boundaries in subsequent compression. © (2011) Trans Tech Publications.