Abstract
An ultrafine-grained EN AW 6082 aluminum alloy was prepared by continuous serve plastic deformation (i.e., thermo-mechanical equal channel angular pressing (ECAP)–Conform process). A miniaturized tensile testing technique was used for estimating local mechanical properties with the aim to reveal the inhomogeneity of elastic and plastic properties in a workpiece volume. These inhomogeneities may appear due to the irregular shear strain distribution in a Conformed wire. Miniaturized samples for tensile testing were cut from the Conformed workpiece. Elongation of miniaturized samples was measured with a 2D digital image correlation technique as the optical extensometer. Tensile test characteristics, such as the yield strength and ultimate tensile strength, were consequently compared with results of conventional and hardness tests. The microstructure of Conformed bars was studied in the cross-section perpendicular and parallel to the extrusion direction using scanning electron microscope (SEM) and electron backscatter diffraction (EBSD) analysis. The microstructure of samples exhibits pronounced inhomogeneity, which is reflected by the hardness and tensile test results. Estimated distinctions between peripheral and central parts of the Conformed wires are probably a consequence of the significant strain differences realized in the upper and bottom wire parts.
Highlights
In the last decades, numerous methods of severe plastic deformation (SPD) have been developed for achieving significant strengthening due to grain refinement [1,2,3,4,5]
If strain is due to one pass through the equal channel angular pressing (ECAP) tool with the angle 90◦, ε ~ 1, it is reasonable to anticipate that the strain introduced in the ECAP–Conform tool will be approximately the same when the cross-sectional area is not changed [7]
The quenched state (QS) material was used for the ECAP–Conform treatment
Summary
Numerous methods of severe plastic deformation (SPD) have been developed for achieving significant strengthening due to grain refinement [1,2,3,4,5]. Besides on the tool geometry, on the procedure parameters (processing temperature, strain rate, back stress) [9,10,11,12]. This is reason why, beside experiments, significant effort is devoted to modeling of SPD processes and computational simulations [13,14]. Miniature specimen test techniques are suitable for materials prepared with SPD methods where only a small amount
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