Mechanical properties of very high strength steel at elevated temperatures

Amin Heidarpour, Niall S. Tofts, Asghar H. Korayem, Xiao Ling Zhao, Christopher R. Hutchinson

Research output: Journal article publicationJournal articleAcademic researchpeer-review

60 Citations (Scopus)


This paper presents a detailed experimental study on the mechanical properties of very high strength (VHS) steel at elevated temperatures. Applications of VHS steel as a structural material are currently limited due to a lack of research supporting its use and relevant design guidelines, such as loading under fire. Samples of VHS steel underwent testing to failure at temperatures ranging from room temperature up to 600 C. The yield strength, ultimate strength and strength relating to 0.5, 1.5 and 2.0% strain were compared with corresponding values for mild and high strength steels available in the literature, and also with empirical equations available in Australian and American standards. Comparisons were made based on the suitability of the standards for application of plastic analysis of the section made of VHS steel at both ambient and elevated temperatures. It is shown that the empirical relations recommended by the standards cannot be used to predict the mechanical properties of VHS steel. The deterioration in VHS steel strength at elevated temperatures is not similar to mild steel or high strength steel. A greater reduction in strength at elevated temperatures is observed and this is because the 'quench and temper' manufacturing process used to create the VHS generates a fundamentally different microstructure, with a different thermal stability, compared to mild and high strength steels. Predictive equations of the reduction factors were proposed for yield strength and ultimate strength for temperatures up to 600 C. The results presented in this paper have the potential for inclusion in the prescriptive code rules for rational fire engineering based designs.

Original languageEnglish
Pages (from-to)27-35
Number of pages9
JournalFire Safety Journal
Publication statusPublished - Feb 2014
Externally publishedYes


  • Elevated temperatures
  • Mechanical properties
  • Rational fire design
  • Very high strength steel

ASJC Scopus subject areas

  • General Chemistry
  • General Materials Science
  • Safety, Risk, Reliability and Quality
  • General Physics and Astronomy


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