The Crystallographic Theory Of Martensite Transformation In Fe Alloys

Based on the assumption that the habit plane is a invariant normal plane or be constructed by some of the invariant normal planes, this paper presents a theory of how to calculate the habit plane when we have known the lattice distortion matrix.Both of the KS mechanism and Nishiyama mechanism of the martensite transformation have been investigated in detail in this paper. According to the assumption that the habit plane is constructed with some of the invariant normal planes, we can obtain the the martensite habit planes. The agreement between theory and experiment is good. The results in this paper show that K-S mechanism and Nishiyama mechanism can account for the relief effects, habit plane, orientation relationship and the change of structure. We give all the martensite variants satisfying both of the K-S mechanism and Nishiyama mechanism of the martensite transformation.This paper presents improved calculation procedures about the Bowles-Mackenzie theory and Wechsler- Lieberman-Resd theory of martensite transformation. The mathematical approach of the new method is different with traditional phenomenological crystallographic theory. Using this method, the crystallography calculation about the matrensite transformation in the Fe-31Ni alloy has been finished. The calculated results are consistent with those of phenomenological crystallographic theory.According to Nishiyama mechanism and the mini-rotation theory presented in this aper, we can explain the transformation mechanisms of Fe-31Ni alloy very well.Also we can explain the transformation mechanisms of Fe-20Ni-5Mn alloy and Fe-8Cr-1C alloy very well, according to Nishiyama mechanism, the K-S mechanism and the mini-rotation theory of this paper.I calculated the martensite transformation of the lath martensite in Fe-20Ni-5Mn iron alloy according to the Nishiyama mechanism and the phenomenal theory of the martensite transformation. The martensite transformation of the plate martensite in Fe-8Cr-1C iron alloy also was calculated according to the K-S mechanism and the phenomenal theory of the martensite transformation. The results are good.Martensitic transformation crystallography was calculated by applying the Empirical Electron Theory of Solids and Molecules (EET),Bond Length Difference (BLD) method and Davies-Magee theory..