Three-dimensional morphology of ferrite formed in association with inclusions in low-carbon steel

Three-dimensional (3D) morphology and growth behavior of ferrite formed at intragranular inclusions in low-carbon steel were studied by serial sectioning and computer-aided visualization. The specimens taken from the weld deposit were austenitized and isothermally reacted for varying times. The length, width, and thickness of ferrite plates were measured from 3D-reconstructed images. From the length-to-width ratio, the morphology of ferrite is likely to be a lath rather than a plate in this alloy. Multivariant ferrite plates (or laths) were observed to be nucleated at inclusions and grow in the directions close to 〈110〉γ with habit planes near {111}γ, probably keeping a fixed orientation relationship with austenite.