Improving the tensile ductility in the fully pearlitic steel using sequential refinement of colony and laminated structure

The enhanced ductility is achieved in pearlitic steels via the successive refinement of colony and lamellar structure induced by the undercooling treatment. The increased high-angle boundaries and low-angle ones with a pronounced accumulation of misorientation within only several micrometers scale are produced in these refined colonies, and both boundary architectures provide larger resistance to dislocations and cracks. The thinned cementite plate with the decreased misfit strain and improved flexibility exhibits better deformation accom-modation with thickened ferrite plates, which greatly delays the deformation among colonies. The cooperation between lamellar structure and colony coupled with its well-improved uniformity is responsible for the enhancement of both uniform and localized ductility, whereas the thinned cementite lamellas with the decreased resistance to dislocations and low-density dislocations primarily account for its reduced strength. This work provides new perspectives for potential technological applications in drawing processes for fully pearlitic steels with high performance.

Automated summary

Enhanced ductility in pearlitic steels is achieved through the refinement of colony and lamellar structure induced by undercooling treatment. The refined colonies have increased high-angle and low-angle boundaries, providing resistance to dislocations and cracks. Thinned cementite plates with decreased misfit strain improve flexibility and delay deformation among colonies. The cooperation between lamellar structure and colony, along with improved uniformity, enhances both uniform and localized ductility.