Growth behavior of ferrite allotriomorphs nucleated on grain boundary faces in a low carbon steel

Abstract

The growth behavior of ferrite allotriomorphs nucleated on grain boundary faces in a low carbon steel was revealed by means of serial sectioning and three-dimensional (3-D) computer-aided reconstruction techniques. The length, width and thickness of ferrite allotriomorphs were measured on the basis of 3-D reconstructed images. The measurements indicated that the lengthening of ferrite allotriomorphs was much larger than that of widening and thickening. As isothermal holding time prolonged, adjacent ferrite allotriomorphs impinged against each other and gradually coalesced and finally covered grain boundary faces. The measured growth rate constant was smaller than that calculated, which was probably attributed to solute drag-like effect of manganese in the alloy.

Microstructure evolution and microhardness of thermal-simulated HAZ in Fe–Mn–Al–C steel

“…When deformed under external stress, the dislocation passes through the κappa carbides by the cutting mechanism. The κappa carbides present at grain boundaries and in grain will block the dislocation movement, resulting in dislocation chocking and reducing the free movement path of dislocation, thus improving the matrix strength [38][39][40]. However, when coarse κappa carbides are formed in the low-density steel, microcracks are easily generated and spread during the deformation process, which greatly reduces the ductility of the lowdensity steel [21].…”