Experimental and Numerical Investigation of the ECAP Processed Copper: Microstructural Evolution, Crystallographic Texture and Hardness Homogeneity

Abstract

The current study presents a detailed investigation for the equal channel angular pressing of pure copper through two regimes. The first was equal channel angular pressing (ECAP) processing at room temperature and the second was ECAP processing at 200 °C for up to 4-passes of route Bc. The grain structure and texture was investigated using electron back scattering diffraction (EBSD) across the whole sample cross-section and also the hardness and the tensile properties. The microstructure obtained after 1-pass at room temperature revealed finer equiaxed grains of about 3.89 µm down to submicrons with a high density of twin compared to the starting material. Additionally, a notable increase in the low angle grain boundaries (LAGBs) density was observed. This microstructure was found to be homogenous through the sample cross section. Further straining up to 2-passes showed a significant reduction of the average grain size to 2.97 µm with observable heterogeneous distribution of grains size. On the other hand, increasing the strain up to 4-passes enhanced the homogeneity of grain size distribution. The texture after 4-passes resembled the simple shear texture with about 7 times random. Conducting the ECAP processing at 200 °C resulted in a severely deformed microstructure with the highest fraction of submicron grains and high density of substructures was also observed. ECAP processing through 4-passes at room temperature experienced a significant increase in both hardness and tensile strength up to 180% and 124%, respectively.

Effect of ECAP on the Plastic Strain Homogeneity, Microstructural Evolution, Crystallographic Texture and Mechanical Properties of AA2xxx Aluminum Alloy

“…Currently, the most suitable route for producing UFG materials is the use of severe plastic deformation (SPD) techniques which can effectively enhance grain refining for industrial applications [22,23]. Several methods have been originated for processing SPD such as equal channel angular pressing (ECAP) [14,[24][25][26][27], high-pressure torsion [18][19][20], twist extrusion (TE) [28], accumulative rolling bonding [29], multi-directional forging [30], multi-channel spiral twist extrude (MCSTE) [15][16][17]31], friction stir welding [32][33][34], rolling in a three high skew rolling mill [35], and extrusion with KOBO [36] for improving ductility and mechanical properties in a wide range of materials. Among various SPD techniques, ECAP fulfilled almost all expectations of an SPD process such as producing nanostructure or UFG structure in metals and alloys as well as its applicability to industrial needs [37][38][39][40].…”

Hardness and Texture of Electrolytic Copper Processed by ECAP at Ambient and Warm Temperature

“…Different when compared to the profile presented by the distribution of hardness in the cold condition. Other researchers [21] also found a microstructure with homogeneous hardness distribution for pure copper, which was processed by ECAP up to the fourth pass via the Bc route in a warm test at 200 °C. This uniform hardness distribution was attributed to the high deformations achieved through multiple-pass processing, which stabilized the sample's internal structure.…”

Advances in Microstructural Characterization of Metals by EBSD

“…Alateyah et al [1] investigated the microstructural evolution and crystallographic texture of copper produced by equal channel angular pressing (ECAP) by EBSD. The as-annealed sample consisted of equiaxed grains with twins and a high density of high angle grain boundaries, while the ECAP samples shown a bimodal microstructure with a higher density of low angle grain boundaries.…”