Acta Metallurgica Sinica (English Letters) ›› 2009, Vol. 22 ›› Issue (2): 100-109.DOI: 10.1016/S1006-7191(08)60076-9

• Research paper • Previous Articles     Next Articles

Effect of silicon and prior deformation of austenite on isothermal transformation in low carbon steels

Minghui CAI1,Hua DING1, Jiansu ZHANG2,Long LI3   

  1. 1) School of Materials and Metallurgy,Northeastern University, Shenyang 110004, China
    2) Technology Center, Baoshan Iron and Steel Co., Ltd., Shanghai 201900, China
    3) National Institute for Materials Science, Tsukuba 305-0047, Japan
  • Received:2008-08-25 Revised:2008-11-21 Online:2009-04-25 Published:2009-10-10
  • Contact: Minghui CAI

Abstract:

Isothermal transformation (TTT) behavior of the low carbon steels with two Si contents (0.50 wt pct and 1.3 wt pct) was investigated with and without the prior deformation. The results show that Si and the prior deformation of the austenite have significant effects on the transformation of the ferrite and bainite. The addition of Si refines the ferrite grains, accelerates the polygonal ferrite transformation and the formation of M/A constituents, leading to the improvement of the strength. The ferrite grains formed under the prior deformation of the austenite become more homogeneous and refined. However, the influence of deformation on the tensile strength of both steels is dependent on the isothermal temperatures. Thermodynamic calculation indicates that Si and prior deformation reduce the incubation time of both ferrite and bainite transformation, but the effect is weakened by the decrease of the isothermal temperatures.

Key words: Low carbon steel, Si content, Prior deformation of austenite, Ferrite transformation, Bainite transformation