Modeling mechanical effects on promotion and retardation of martensitic transformation

Research highlights: → Compressive elastic stresses up to 250 MPa are applied in continuous cooling. → Using the thermodynamic data and maximum value of the mechanical driving force the predicted increase in Ms (∼0.1 K/MPa) is in agreement with experiment → Austenite was deformed plastically at different temperatures (800 deg. C-1100 deg. C). → High deformation temperature (i.e. 1100 deg. C) as well as low plastic strain (i.e. εave ∼ 30%) do not affect martensite transformation noticeably, whereas lower deformation temperature (e.g. 900 deg. C) and large plastic strain (i.e. εave ∼ 70%) retards martensite transformation. → The theory of mechanical stabilization predicts the depression of Ms. - Abstract: The influence of compressive stress and prior plastic deformation of austenite on the martensite transformation in a eutectoid steel is studied both experimentally and theoretically. It is demonstrated that martensite formation is assisted by stress but it is retarded when transformation occurs from deformed austenite. With the quantitative modeling of the problem based on the theory of displacive shear transformation, the explanation of the two opposite roles of mechanical treatment prior to or simultaneously to martensite transformation is presented.