Tailoring the crack-tip microstructure: a novel approach

This investigation demonstrates a way to innovatively modify the ferritic microstructure at a local scale, particularly at the failure prone area such as Charpy V-notch (CVN) root. Tensile pre-strain (PS) up to 6% and 12% were employed before annealing (An) the samples at 650 degrees C for 15minutes. Ferrite grain size increased sharply and gradually (along the distance ahead of the notch root) within the microstructurally modified region in 6-12% pre-strained and annealed samples, respectively. The critical strain which promotes strain-induced boundary migration (SIBM), was found to be 0.1 which resulted in abnormally coarse ferrite grains.