The optimum grain size for strength-ductility combination in metals

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

19 Scopus Citations
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Author(s)

  • Yanfei Wang
  • Chongxiang Huang
  • Jianfeng Zhao
  • Fengjiao Guo
  • Xiaotian Fang
  • Yueguang Wei

Detail(s)

Original languageEnglish
Article number103574
Journal / PublicationInternational Journal of Plasticity
Volume164
Online published27 Feb 2023
Publication statusPublished - May 2023

Abstract

A strength-ductility trade-off usually occurs when grains are refined to increase strength. A question arises on if there exists a grain size for the best strength-ductility combination, i.e., with the highest possible strain energy density limit and strength simultaneously. This issue is crucial for guiding the design of strong and tough structural materials. Here we reveal an optimum grain size (doptimum) on the order of a few micrometers, at which the strain energy density limit, esti-mated as the product of strength and uniform elongation, reaches a maximum while maintaining reasonably high yield strength. The doptimum is found to exist in a series of single-phase FCC, BCC and HCP materials, indicating it as a universal phenomenon. Theoretical models on the grain size-dependence of uniform elongation and ultimate strength are developed by considering dislocation accumulation in grain boundary affected region (Gbar) and grain interior based on the classical Kocks-Mecking-Estrin model. Combined with the Hall-Petch relationship, the models accurately predict the doptimum. Importantly, the models disclose this doptimum to be close to twice of the characteristic width of Gbar (lGbar), suggesting that it is exactly at or near the critical grain size with the strongest intragranular strain gradient effects.

Research Area(s)

  • Strength and ductility, Grain size effect, Grain boundary affected region, Geometrically necessary dislocations, Heterostructure, HIGH-TENSILE DUCTILITY, CU-AL ALLOYS, MECHANICAL-PROPERTIES, MICROSTRUCTURAL EVOLUTION, YIELD-STRESS, BACK STRESS, IF STEEL, PURE CU, DEFORMATION, PLASTICITY

Citation Format(s)

The optimum grain size for strength-ductility combination in metals. / Wang, Yanfei; Huang, Chongxiang; Ma, Xiaolong et al.
In: International Journal of Plasticity, Vol. 164, 103574, 05.2023.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review