We examine here the physical aspects and input parameters of a recently published model on the overall transformation kinetics of the bainite reaction in steels.

Experimental results and explanations for the transition temperature from upper to lower bainites in carbon steels containing from 0.20 to 1.80 wt%C were presented metallographically and kinematically. The experimental results are summarized as follows: I) Lower bainite is not formed in steels with less than 0.35 wt%C and no transition from upper to lower bainite occurs. 2) The transition tempe...

SEPTEMBER 2006 -s 200 ABSTRACT. The relationship between alloying content, microstructure, and properties has been clarified for highstrength steel weld metals with 7 to 9 wt-% nickel. Neural network modeling suggested that manganese reductions and nickel additions in a controlled manner with respect to manganese lead to increased impact toughness. Carbon additions were predicted to enhance yie...

The T0 temperature in steel is defined as that at which ferrite and austenite of the same chemical composition have identical free energy. The T0 temperature is that below which it is possible for austenite to transform to ferrite of the same chemical composition after allowing for the strain energy due to the displacements associated with the transformation. Bainite is expected below the T0 te...

The kinetics and mechanism of bainite transformation have been studied in Fe-Cr-Mo-V-Ti-C steel high speed dilatometry backed by thermodynamic analysis. The complete transformation of austenite, however, has not occurred at any reported temperature. Obtained results confirm the incomplete reaction phenomenon with the cessation of the bainite transformation well before the paraequilibrium is ach...

X90 pipeline steel was processed with the simulated coarse grain heat affect zone (CGHAZ) thermal cycle with heat input varying from 30 kJ/cm to 60 kJ/cm, the microstructures were investigated by means of optical microscope (OM), scanning electron microscope (SEM), electron backscattering diffraction (EBSD), and transmission electron microscope (TEM), and the impact properties were evaluated fr...

Nanostructured bainite is a novel ultra-high-strength steel-concept under intensive current research, in which the optimization of its mechanical properties can only come from a clear understanding of the parameters that control its ductility. This work reviews first the nature of this composite-like material as a product of heat treatment conditions. Subsequently, the premises of ductility beh...

New developments with bainite have resulted in a steel with an ultimate tensile strength of 2500 MPa, a hardness of 600-670 HV and a toughness in excess of 30-40 MPa m [1]. The novel microstructure is generated in a high carbon (0.98 wt.%) high silicon (1.46 wt.%) steel austenitized for 15 min. at 1000 oC, and then isothermally transformed at temperatures of ∼200 oC. Iron does not diffuse durin...