Effects of plastic deformation and heat treatment on microstructure and properties of high boron cast steel

High boron cast steel is brittle owing to the network of boride which limits its applications. In order to improve its toughness, the high boron cast steel was treated with combined processes of plastic deformation and heat treatment as will be discussed in this article. The prepared samples were analyzed using scanning electron microscope (SEM), transmission electron microscopy (TEM), and x-ray diffraction (XRD). The results show that plastic deformation breaks up boride network and uniformly distributes broken boride particles in the matrix. During subsequent heat treatment, spheroidized borides are obtained. Compared with undeformed samples after heat treatment, the hardness of the deformed samples after heat treatment increases marginally (from 51.4 to 54.7 HRC) while the toughness increases considerably (from 5 to 107 J/cm ²). Fracture surface changes from brittle morphology to dimple morphology.