Reverse aging of steel wire rods: The influence of microstructure

In the production of steel wire rod, the recovery of deformability after hot rolling is a well-known phenomenon related to hydrogen diffusion. High carbon steels are strongly affected by this issue, as reported in technical literature. However, there is a lack of information regarding medium to low carbon steels. This work investigated the influence of the chemical composition, of the rolling process, and of the Stelmor cooling strategy on the recovery of deformability of six steel. The recovery process was linked to the percentage of pearlite through an exponential equation, and the maximum observed recovery was 80%. Scanning electron microscopy was used to characterise the evolution of the mechanical behaviour of the material by observing the fracture surfaces of the tensile specimen. Furthermore, the recovery of deformability was linked to hydrogen diffusion using the finite differences method to approximate Fick's second law.