Study guide
An extremely fine, fully pearlitic structure with an interlamellar spacing of 30–50 nm has been obtained during continuous cooling transformation at a rate as low as 0.1 °C s−1, of the steel that is normally used to produce nanostructured bainite. The solutes cobalt and aluminium have been added to accelerate the rate of reaction and reduce the interlamellar spacing by increasing the free energy of transformation. The range of cooling rates over which the fully pearlitic state can be achieved is characterised.
A method has been discovered to produce fine pearlite by applying continuous cooling transformation to specific steels. By incorporating cobalt and aluminium into the chemical composition, the transformation driving force is increased, allowing for a refined internal structure without the need for expensive magnetic fields. This chemical modification successfully reduced the interlamellar spacing to between 30 and 50 nanometres, even at very slow cooling speeds. The study demonstrates that these nanostructured materials achieve significantly higher Vickers hardness levels compared to standard pearlite. Ultimately, the results show that the material strength is directly dictated by the tightness of the internal spacing (S) created during the cooling process. This research provides a cost-effective pathway for designing high-strength steels with superior mechanical properties.
Scripta Materialia 67 (2012) 53–56
