J. Mater. Sci. Technol. ›› 2021, Vol. 78: 247-259.DOI: 10.1016/j.jmst.2020.11.034

• Review Article • Previous Articles     Next Articles

Crystallographic texture evolution and martensite transformation in the strain hardening process of a ferrite-based low density steel

Mingxiang Liua,b, Changjiang Songa,*(), Zhenshan Cuib,*()   

  1. aCenter for Advanced Solidification Technology, School of Materials Science and Engineering, Shanghai University, Shanghai, 200444, China
    bInstitute of Forming Technology and Equipment, School of Materials Science and Engineering, Shanghai Jiao Tong University, 1954 Huashan Road, Shanghai, 200030, China
  • Received:2020-08-05 Revised:2020-10-20 Accepted:2020-11-01 Published:2021-07-10 Online:2020-11-28
  • Contact: Changjiang Song,Zhenshan Cui
  • About author:cuizs@sjtu.edu.cn(Z. Cui).
    *E-mail addresses:riversong@shu.edu.cn(C. Song);

Abstract:

The strain-induced martensite transformation is of great importance in the strain hardening process of ferrite based low-density steel. Based on the microstructure analysis, the texture evolution and martensite transformation behavior in the strain hardening process were studied. The results show that martensite transformation accompanied by TWIP effect and high density dislocations maintains the continuous hardening stage. As the strain increases, the texture of retained austenite evolves towards the Forientation {111}<112>, which is not conducive to martensite transformation. After the strain of 5%, the number of austenite grains with high Schmid factor orientations is gradually increased, and then significantly reduced when the strain is over 10 % due to the occurrence of martensitic transformation, which results in a high martensitic transformation rate. However, the unfavorable orientation and the reduced grain size of austenite slow down the martensite transformation at the final hardening stage. Moreover, because of the coordination deformation of austenite grains, strain preferentially spreads between adjacent austenite grains. Consequently, the martensite transformation rate in strain hardening process is dependent on the orientation and grain size evolution of austenite, leading to a differential contribution to each strain hardening stage.

Key words: Low density steel, Strain hardening, Texture, TRIP, Deformation behavior