Acta Metallurgica Sinica (English Letters)

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Influence of Strain Rate on Tensile Characteristics of SUS304 Metastable Austenitic Stainless Steel

Xifeng LI, Jun CHEN, Liyan YE, Wei DING, Pengchao SONG   

  1. Department of Plasticity Technology, School of Materials Science and Engineering, Shanghai Jiao Tong University,Shanghai 200030, China
  • Received:2013-04-09 Revised:2013-05-20 Online:2013-12-25 Published:2014-02-28
  • Contact: Jun CHEN
  • Supported by:

    National Natural Science Foundation of China (No. 51105248) and Specialized Research Fund for the Doctoral Program of Higher Education (No. 20090073120058).

Abstract:

The microstructure characteristics and plastic deformation behavior of SUS304 metastable austenitic stainless steel sheets have been investigated during tensile process at different strain rates at room temperature. The yield stress continuously increases with strain rates due to low fraction of martensite transformed from austenite at 0.2% plastic stain. While the ultimate tensile stress (UTS) and elongation gradually decreases and then slightly increases with increase in strain rate from 0.0005 s- 1 to 0.1 s- 1, which is attributed to the variation of the martensite fraction that is affected seriously by adiabatic heating. A higher temperature increase in the tensile specimens restricts the martensitic transformation at high strain rate. The strain rate of 0.1 s-1 is considered as a transition deformation rate from quasi-static state to plastic forming, where the transformed martensitic content is very small in a higher strain rate range. Anomalous stress peaks in the later half stage of deformation occur at a very low strain rate (i.e., 0.0005 s- 1) result from X-shaped strain localization repeatedly sweeping over the specimen. With increasing strain rates, the variation of dimple number density follows similar trend as that of UTS and ductility because martensite fraction mostly influences void nucleation and growth.

Key words: SUS304 metastable austenitic stainless steel, Strain rate, Mechanical properties, Martensite fraction, Dimple