Martensite laths in creep resistant martensitic 9–12% Cr steels — Calculation and measurement of misorientations

The morphology and crystallography of a martensitic creep resistant 9–12% Cr steel were examined by EBSD to analyse the misorientations of martensite lath boundaries. The results are compared to the theoretical values given by the models of Kurdjumov–Sachs and Nishiyama–Wassermann. It turns out that these models are not sufficient to fully understand the measured microstructure. As a consequence, a mixed model is introduced, which combines K–S and N–W. It is shown, that the mixed model predicts the experimental findings with high accuracy.