The fracture toughness of molybdenum at different grain sizes under and since brittle-ductile transition: computer modeling and experiment

TL;DR

This paper investigates how grain size affects molybdenum's fracture toughness across the brittle-ductile transition, combining computer modeling and experiments to reveal dislocation behavior near grain boundaries.

Contribution

It introduces a dislocation dynamics model to analyze the impact of grain boundaries on fracture toughness evolution in molybdenum.

Findings

Fracture toughness increases when dislocations reach grain boundaries.

Large grain sizes have minimal effect on dislocation ensembles and toughness.

Dislocation distribution changes at grain boundaries influence toughness growth.

Abstract

The sharp growth of the fracture toughness after brittle-ductile transition happens at grain sizes approximately equal to the plastic zone size. Here we analyze the influence of the grain boundary on the evolution of the ensemble of dislocations near the crack tip using dislocation dynamics method. We show evidence that for large grain sizes, the size has little effect on the ensemble of dislocations and the fracture toughness, but when dislocations reach the grain boundary, distribution of dislocations changes, which leads to increase of the fracture toughness.