Bainite Morphology in Two Experimental Mo-Cr and Mo-Cr-V-Ti Steels

Abstract

The paper presents an investigation of the bainite morphology in two experimental Mo-Cr and Mo-Cr-V-Ti steels using TEM, high speed dilatometry backed by thermodynamic analysis. The microstructure was investigated using metallography and TEM method. After austenitisation at 1200 o C followed by bainitic reaction in upper and lower temperatures of isothetmal transformation the bainite was in the form of classical sheaves. The amont, distribution and morphology of retained austenite and bainitic ferrite depend on prior austenitisation and isothermal transformation temperatures within the bainitic range.

Rationalisation of Austenite Transformation to Upper or Lower Bainite in Steels

“…The composition of the investigated steel and calculated B S and M S temperatures are given in Table 1. In agreement with the previous observations the Fe-C-Cr steel seems to be ideal for testing the change from upper to lower bainite in the transition temperature [7,14,15]. [16,17] A high-speed Adamel Lhomargy LK-02 dilatometer was used to establish change of length (∆L/L) during isothermal bainitic transformation.…”