Tailoring the crack-tip microstructure: A novel approach

TL;DR

This paper presents a novel method to locally modify ferritic microstructure at crack-prone areas by applying tensile pre-strain followed by annealing, resulting in controlled grain size changes to improve material performance.

Contribution

It introduces a new microstructural tailoring technique using tensile pre-strain and annealing to modify ferrite grain size near failure zones.

Findings

Ferrite grain size increases with pre-strain and annealing.

Critical strain for boundary migration is 0.1.

Coarse grains form at high pre-strain levels.

Abstract

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 percent and 12 percent were employed before annealing (An) the samples at 650{\deg}C for 15 minutes. Ferrite grain size increased sharply and gradually (along the distance ahead of the notch root) within the microstructurally modified region in 6-12 percent pre-strained and annealed samples, respectively. Critical strain which promotes strain induced boundary migration (SIBM), was found to be 0.1 which resulted in abnormally coarse ferrite grains.