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Updated: Dec 22, 2025

Determining the Mechanical Strength of Ultra-Fine-Grained Metals
Published on: November 22, 2021
Making ultrastrong steel tough by grain-boundary delamination
1Department of Mechanical Engineering, University of Hong Kong, Pokfulam Road, Hong Kong, China.
Abstract:
Developing ultrahigh-strength steels that are ductile, fracture resistant, and cost effective would be attractive for a variety of structural applications. We show that improved fracture resistance in a steel with an ultrahigh yield strength of nearly 2 gigapascals can be achieved by activating delamination toughening coupled with transformation-induced plasticity. Delamination toughening associated with intensive but controlled cracking at manganese-enriched prior-austenite grain boundaries normal to the primary fracture surface dramatically improves the overall fracture resistance. As a result, fracture under plane-strain conditions is automatically transformed into a series of fracture processes in "parallel" plane-stress conditions through the thickness. The present "high-strength induced multidelamination" strategy offers a different pathway to develop engineering materials with ultrahigh strength and superior toughness at economical materials cost.
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