Synergistic effects of Cu and Ni on nanoscale precipitation and mechanical properties of high-strength steels

Zengbao Jiao, J. H. Luan, Z. W. Zhang, M. K. Miller, W. B. Ma, C. T. Liu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

119 Citations (Scopus)

Abstract

There is an increasing demand for ultrahigh-strength ferritic steels strengthened by nanoprecipitates. Improvement of the precipitation strengthening response requires an understanding of the nanoscale precipitation mechanisms. In this study, the synergistic effects of Cu and Ni on nanoscale precipitation and mechanical properties of ferritic steels were thoroughly investigated, and new steels with ultrahigh strength and high ductility have been developed. Our results indicate that Ni effectively increases the number density of Cu-rich nanoprecipitates by more than an order of magnitude, leading to a substantial increase in yield strength. It appears that Ni decreases both the strain energy for nucleation and the interfacial energy between the nucleus and the matrix, thereby decreasing the critical energy for nucleation of Cu-rich nanoprecipitates. Cu and Ni are also found to be beneficial to grain-size refinement, resulting from lowering the austenite-to-ferrite transformation temperature, as determined from thermodynamic calculations. In addition, the strengthening mechanisms of Cu and Ni were quantitatively evaluated in terms of precipitation strengthening, grain refinement strengthening and solid-solution strengthening. The current findings shed light on the composition- microstructure-property relationships in nanoprecipitate-strengthened ferritic steels.
Original languageEnglish
Pages (from-to)5996-6005
Number of pages10
JournalActa Materialia
Volume61
Issue number16
DOIs
Publication statusPublished - 1 Sep 2013
Externally publishedYes

Keywords

  • Alloy development
  • Cu-rich nanoprecipitate
  • Grain-size refinement
  • Nanoscale precipitation
  • Ultrahigh-strength steel

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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