Carbon content of bainite ferrite in 40CrMnSiMoV steel

A refined method for analysing X-ray diffraction spectrum was used to determine the carbon content of bainite ferrite in 40CrMnSiMoV steel. The supersaturated carbon concentration linearly decreases with increase of isothermal holding time at 310 °C due to the carbon repartition and carbide precipitation. The deduced carbon content of lower bainite embryo in the steel is 0.36 wt%, which agrees well with the prediction from the mechanism that bainite forms in carbon depleted regions in supercooling austenite through martensitic shear.