Analysis of Deformation Behaviour and Residual Stress in Rotary Swaged Cu/Al Clad Composite Wires

Abstract

Both copper and aluminum are widely applicable throughout a variety of industrial and commercial branches, however, joining them in a composite provides the possibility of combining all their advantageous properties in one material. This study investigates uniquely sequenced copper–aluminum clad composite wires, fabricated via rotary swaging technology. The composites were processed at 20 °C and 250 °C to a diameter of 5 mm. Structural observations and the determination of residual stress within both elements of the swaged wires were performed via electron microscopy; the experimental results were correlated with numerical predictions. As shown in the results, both the applied swaging force and temperature affected the plastic flow, which had a direct influence on residual stress and texture development; the Alsheath elements exhibited ideal rolling textures, whereas the Cuwires elements featured ideal shear texture orientation. The grains within both the Alsheath elements of the 5 mm composite wire were refined down to sub-micron size. Structural restoration also had a positive influence on residual stress.

Structural Phenomena Introduced by Rotary Swaging: A Review

“…On the other hand, the grains detected w the outer Al layer were larger but with a more substantial development of subg Compared with the inner Al layer, the outer one was subjected to a greater amou imposed shear strain, and thus the chain of strain hardening-softening microstru phenomena developed to a greater extent therein. Similar variations between externa internal layers of the same metals were also confirmed for different types of sw laminates (e.g., for Cu lamellas and Cu core of a laminate featuring an Al sheath Moreover, by varying the processing conditions, the optimization of the properti mutual Al-Cu interfaces can be achieved [94,100,101], see also Figure 4a,b For example, for a laminated rod consisting of Al-Cu-Al layers subjected to room temperature RS with a swaging degree of 2.2, different structure-forming phenomena within the Al layers were observed, according to its particular location [95]. Within the inner Al core, narrow bands of refined grains of widths ranging between 2 µm and 25 µm (sizes of individual grains) were observed-these bands further featured the presence of subgrains with sizes from 0.2 µm to 1.0 µm.…”

“…As for such composites, the microstructure development within the individual metals is comparable to single-phase metals. However, certain differences can be observed due to differences in the plastic flows of the individual components-especially for laminates, as the distribution of the metallic components across their cross-sections is typically not uniform (see the distribution of the imposed strain during rotary swaging of a clad composite consisting of Al sheath and Cu wires, predicted via the finite element method, in Figure 7a,b [100]).…”

“…As for such composites, the microstructure development within the indiv metals is comparable to single-phase metals. However, certain differences can be obse due to differences in the plastic flows of the individual components-especiall laminates, as the distribution of the metallic components across their cross-sectio typically not uniform (see the distribution of the imposed strain during rotary swagi a clad composite consisting of Al sheath and Cu wires, predicted via the finite ele method, in Figure 7a,b [100]). For example, for a laminated rod consisting of Al-Cu-Al layers subjected to temperature RS with a swaging degree of 2.2, different structure-forming pheno within the Al layers were observed, according to its particular location [95].…”

“…Similar variations between external and internal layers of the same metals were also confirmed for different types of swaged laminates (e.g., for Cu lamellas and Cu core of a laminate featuring an Al sheath [99]). Moreover, by varying the processing conditions, the optimization of the properties of mutual Al-Cu interfaces can be achieved [94,100,101], see also Figure 4a Cu has also advantageously been combined with other metals to prepare various composites, for example Tian et al [102] combined Cu with Mg to fabricate a laminated wire via cold RS; by applying a reduction of up to 71%, they achieved wires with the UTS reaching 290 MPa and an electric conductivity of up to 81.1% IACS. Yu et al [103] used RS at 950 °C to manufacture a W-Cu composite from original powders, the deformation processing not only provided favorable strength but also ensured the density exceeding 99%, whereas Kocich et al [62] used RS at both room and elevated (400 °C and 600 °C) temperatures to fabricate Cu composites reinforced with Al2O3 particles featuring UFG microstructures (average grain size refined down to 1.2 µm 2 for the composite swaged at room temperature).…”

Optimizing Thermomechanical Processing of Bimetallic Laminates

“…Among the possible applications are, e.g., Al + Cu clad armored cables [37], laminated tubes for air conditioners [38], and rail transit wires [39]. In particular, the application of Al + Cu bimetallic laminates for electroconductive applications is highly promising, since the (partial) replacement of Cu by Al results in decreased weight and enhanced mechanical and utility properties of the electroconductive cable with no significant deterioration of the electric characteristics [40].…”