Dual rolls equal channel extrusion as unconventional SPD process of the ultralow-carbon steel: finite element simulation, experimental investigations and microstructural analysis

Abstract

The paper presents results of FEM modelling as well as properties and microstructure of the ultralow-carbon ferritic steel after the unconventional SPD process—DRECE (dual rolls equal channel extrusion). Based on the conducted numerical simulation information about the deformation behaviour of a steel strip during the DRECE process was obtained. The simulation results were experimentally verified. The influence of DRECE process on hardness distribution, fracture behaviour and microstructure evolution of the investigated steel was analysed. The increase of steel strength properties after subsequent deformation passes was confirmed. The microstructural investigations revealed that the processed strips exhibit the dislocation cell microstructure and subgrains with mostly low-angle grain boundaries. The grains after processing had relatively high dislocation density and intense microband formation was observed. It was also proved that this unconventional SPD method fosters high grain refinement.

Effect of Processing Route on Microstructure and Microhardness of Low-Carbon Steel Subjected to Drece Process

“…The DRECE method (Dual Rolls Equal Channel Extrusion) [4][5] is based on the principle of angular extrusion through an equilateral channel using contact friction between the extruded blank, in the form of a sheet metal strip, and feed rollers. Based on the generated friction force, the sheet is continuously extruded into a special forming tool, where it is intensively deformed by shear deformation as it passes through the deformation zone.…”

“…Figure 1 Schematic illustration of DRECE device [4] Due to the technological aspects of DRECE extrusion, the deformation is unevenly spread over the thickness of the sheet metal. From the results presented in [4], the largest deformation values are localized in the surface area of the extruded belt, where the deformation value is approximately 0.71 and this value in the thickness direction decreases to 0.45.…”

“…Figure 1 Schematic illustration of DRECE device [4] Due to the technological aspects of DRECE extrusion, the deformation is unevenly spread over the thickness of the sheet metal. From the results presented in [4], the largest deformation values are localized in the surface area of the extruded belt, where the deformation value is approximately 0.71 and this value in the thickness direction decreases to 0.45. Heterogeneous deformation leads to uneven grain softening due to the application of the forming process and at the same time negatively affects the resulting mechanical properties of the forming sheet.…”

The effect of severe plastic deformation on the IF steel properties, evolution of structure and crystallographic texture after dual rolls equal channel extrusion deformation

“…The shaping process is based on the extrusion technology with zero reduction of strip's thickness while achieving a high degree of deformation in the material being formed. [23][24][25]. Multiple plastic deformations carried out this way determine the change of the structure and mechanical properties in relation to the initial material.…”

The influence of post-deformation annealing temperature on the mechanical properties of low-carbon ferritic steel deformed by the DRECE method

“…This method involves repeated passes of steel strips between a set of dies, with angle formation defined by the shaping tool. The multiple deformation affects the refinement of the microstructure and thus causes a related * E-mail: Karolina.Kowalczyk@polsl.pl improvement in mechanical properties compared to the initial state of the material [9]. A detailed description of the DRECE method can be found in Rusz et al [10].…”