Microstructural Evolution of a 3003 Based Aluminium Alloy during the CSET Process

Abstract

A new severe plastic deformation technique, known as the complex shearing of extruded tube (CSET), was applied to a 3003 based model aluminium alloy. This technique, consisting of a combination of extrusion and two consecutive Equal Chanel Angular Pressing (ECAP) passes accompanied with concurrent torsional straining, is capable to produce a fine-grained tubular sample directly from a bulk metallic cylinder in one forming operation. In the present paper, the microstructural development of the alloy during partial processes of CSET was studied in detail using light microscopy, electron backscatter diffraction, and transmission electron microscopy. It was found that CSET technique refines the grain size down to 0.4 µm and, consequently, increases the microhardness from the initial value of 40 HV to the final value of 120 HV. The contributions of partial processes of CSET to the total strain were estimated.

The Role of Mandrel Rotation during CSET Processing Demonstrated on a 3003 Aluminium Alloy

“…These results show the ability of the torsional straining to reduce the grain size of the processed material. These HPTT and HPT like deformation processes were shown in [18] to lead to grain refinement in the CSET processed 3003 aluminium alloy even before the ECAP passes. These processes resulted in a substantial grain refinement also in the present research due to combined effect of the strain energy stored during severe plastic deformation and additional rotational deformation.…”

“…The schematic detail of MDZ in Figure 10 shows that following SPD processes are applied consecutively: Each of these processes contributes to the equivalent strain cumulated in the processed sample. It was shown in [18] that the tube extrusion and two ECAP passes, which are the only deformation processes during CSET with stationary mandrel, lead to an equivalent strain of approximately 4. The rotational movement of the mandrel results in additional shearing due to the friction between the rotating mandrel and the sample surface and enhances the cumulative equivalent strain.…”

“…All the mentioned methods were developed to apply initially tubular samples. Recently, we developed the method called complex shearing of extruded tube (CSET) which is capable to prepare tubular sample with an ultra-fine-grained microstructure and enhanced strength in one step from a cylindrical bulk sample [17,18]. This method combines the tube extrusion ensued by two consecutive ECAP passes.…”

“…Additionally, the mandrel can rotate and introduce further twist deformation into the tube due to friction between the rotating mandrel and produced tube. The role of individual partial deformation processes was described and discussed in [18]. The microstructural development during different stages of CSET along with mechanical properties was studied on a 3003 aluminium alloy.…”

“…The microstructural development during different stages of CSET along with mechanical properties was studied on a 3003 aluminium alloy. An overall grain refinement by 3 orders of magnitude was reported which led to remarkable hardness enhancement [18].…”