Spannungsabhängiges bainitisches und martensitisches Umwandlungsverhalten eines niedrig legierten Stahls

The effect of constant uniaxial stresses on the bainiric and the martensitic transformation behaviour was studied in a low alloy steel. The experimental results demonstrated that both tensile and compressive stresses significantly affect the kinetics of the phase transformation. Simultaneous measurements of axial and diametral strains allowed for calculation of the amount of transformation plasticity as a function of temperature, time, and the external stress. The stress effects on the isothermal transformation behaviour were found to be most pronounced slightly above the martensite start temperature, The data obtained are shown to be only partially compatible with current models. Thus, the resulting microstructures were characterized both by optical and electron microscopy in order to shed light on the relevant microstructural processes that have to be accounted for in developing improved models. First results already demonstrate that the resulting microstructure is substantially affected by the presence of external stresses.