Effect of interlamellar spacing on fracture toughness of nano-structured pearlite

Microstructural refinement to the nanoscale imparts tremendous strength to metals while following the Hall-Petch relationship. However, most manufacturing methods to make nanostructured metals are limited by the maximum size of the final product. Extremely fine pearlitic steels with mean true inter-lamellar spacing of 110 nm and 63 nm while having yield strength of 0.79 GPa and 1.08 GPa respectively have been produced by suitable alloying and appropriate undercooling to enhance the free energy available for transformation. The stronger pearlite shows enhanced plane strain fracture toughness thus offering a combination of high damage resistance and tolerance.