Simulation of martensitic microstructures in a low-alloy steel

The martensite structure of steel is of great importance in mechanical engineering and is usually adjusted by heat treatment. Of particular interest is the morphology of martensite, as it has a significant influence on mechanical properties. In this work, a phase field model is presented, where the order parameter is used to describe the evolution of martensite in order to predict the resulting morphology. In a first step, simulations with two martensite variants with different transformation strains by means of the finite element method in the small strain context show the basic applicability of the model in a two-dimensional environment. With a concept based on the phenomenological theory of martensite crystallography, good agreement with the transformation mechanics of the experiment is achieved. Furthermore, an illustrative three-dimensional simulation takes the crystallographic variants of the Nishiyama-Wasserman orientation relationship into account. The size of the simulation domain corresponds to the size of a prior austenite grain. The calculated block sizes agree with the experimental observations.