Determination of the continuous cooling transformation diagram of a high strength low alloyed steel

The continuous cooling transformation diagram of a high strength low alloyed steel was determined by a dilatometer and microscopic analysis (OM, SEM) as well as thermodynamic analysis. As expected, Widmanstätten ferrite, bainite and martensite coexisted for most cooling rates, which made it difficult to determine the transformation kinetics of individual phases. However, peaks were clearly observed in the dilatometric d( LVDT)/dT curves. By overlapping the d( LVDT)/dT curves, which were determined using various cooling rates, peaks were separated and the peak rate temperatures, as well as the temperature at the start of transformation (5