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Subject: search.filters.subject.Copper alloy

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    Numerical investigation of plastic strain homogeneity during equal-channel angular pressing of a Cu-Zr Alloy
    (2021-12-01)
    Wongsa-Ngam, Jittraporn
    ;
    Noraphaiphipaksa, Nitikorn
    ;
    Kanchanomai, Chaosuan
    ;
    Langdon, Terence G.
    A three-dimensional finite element method (3D FEM) simulation was carried out using ABAQUS/Explicit software to simulate multi-pass processing by equal-channel angular pressing (ECAP) of a circular cross-sectional workpiece of a Cu-Zr alloy. The effective plastic strain distri-bution, the strain homogeneity and the occurrence of a steady-state zone in the workpiece were investigated during ECAP processing for up to eight passes. The simulation results show that a strain inhomogeneity was developed in ECAP after one pass due to the formation of a corner gap in the outer corner of the die. The calculations show that the average effective plastic strain and the degree of homogeneity both increase with the number of ECAP passes. Based on the coefficient of variance, a steady-state zone was identified in the middle section of the ECAP workpiece, and this was numerically evaluated as extending over a length of approximately 40 mm along the longitudinal axis for the Cu-Zr alloy.
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    Wear resistance of an ultrafine-grained Cu-Zr alloy processed by equal-channel angular pressing
    (2015-03-05)
    Li, Jianwei
    ;
    Wongsa-Ngam, Jittraporn
    ;
    Xu, Jie
    ;
    Shan, Debin
    ;
    Guo, Bin
    A Cu-0.1 wt.% Zr alloy was processed by equal-channel angular pressing (ECAP) through 8 passes at room temperature to produce an ultrafine grain size of ~350 nm with an average Vickers microindentation hardness (200 gf) of ~140. Ball-on-disc dry sliding tests were conducted on an annealed material and on the ECAP-processed alloy using applied normal loads from 1 to 15. N. The coefficient of friction (COF), surface topography and wear volume loss were examined to evaluate the micro-wear resistance. The results show that samples processed by ECAP have lower average values for the COF than the unprocessed alloy and there is also a decrease in the wear depth and wear volume loss with increasing numbers of ECAP passes. The ultrafine-grained alloy processed by ECAP has a higher wear resistance than the annealed and unprocessed material due to the significant grain refinement and improved mechanical properties.
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    An examination of the saturation microstructures achieved in ultrafine-grained metals processed by high-pressure torsion
    (2014-10-01)
    Sabbaghianrad, Shima
    ;
    Wongsa-Ngam, Jittraporn
    ;
    Kawasaki, Megumi
    ;
    Langdon, Terence G.
    Experiments were conducted on two commercial alloys, a Cu-0.1%Zr alloy and an Al-7075 aluminum alloy, to investigate the significance of the saturation microstructure which is achieved after processing by high-pressure torsion (HPT). Samples were processed by HPT and also by a combination of equal-channel angular pressing (ECAP) followed by HPT. The results show that the saturation conditions are dependent upon the grain size in the material immediately prior to the HPT processing. Additional grain refinement may be achieved in HPT by initially processing the material to produce an ultrafine-grain size before conducting the processing by HPT.
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    Microstructural evolution and grain refinement in a Cu-Zr alloy processed by high-pressure torsion
    (2014-01-01)
    Wongsa-Ngam, Jittraporn
    ;
    Langdon, Terence G.
    A copper alloy, Cu-0.1% Zr, was processed at room temperature by high-pressure torsion (HPT) in order to evaluate the microstructural evolution and grain refinement mechanism. Transmission electron microscopy (TEM) and electron backscatter diffraction (EBSD) techniques were employed to measure the grain morphology, grain size distributions and the distribution of the misorientation angles. The results demonstrate that this processing procedure has a potential for producing an ultrafine-grain structure containing reasonably equiaxed grain with high-angle boundary misorientations. The grain refinement mechanism is primarily governed by dislocation activities. © (2014) Trans Tech Publications, Switzerland.