EBSD analysis of microstructure between liquid core forging process and traditional forging process

Assab 718 was a kind of plastic die steel and the daughter grains were the tempered sorbite after normalizing and high-temperature tempering. The daughter grains had a specific orientation relationship with the parent grains, which could be reconstructed based on the electron backscattered diffraction tests. The evolution laws from the parent grains to the daughter grains under the two forging processes were compared by HKL Channel 5. The results showed that the parent grains were finer and more evenly distributed under the new process. The recrystallization volume fraction of those grains was less than that under the traditional one. From the parent grains to the daughter grains, the orientation of the maximum texture intensity and the maximum section location was changed under the liquid core forging process. While the orientation of the maximum texture intensity of the parent grains under the traditional one was a common S-texture and that of the daughter grains was not obvious. The geometrically necessary dislocation density was calculated based on the kernel average misorientation. This study is necessary to reveal the micro-deformation mechanism of the new and the traditional forging processes. It can provide theoretical guidance for implementing the liquid core forging process.