Abstract
Equal channel angular pressing (ECAP) has the advantage of enabling an ultrafine grain size. Aluminum 1060 is used as a power plant material because of its favorable electrical properties. However, the weak strength of aluminum limits its application. In this study, the thermal conductivity and electrical conductivity of Al 1060 made by ECAP was investigated. ECAP was conducted through the die having a channel angle of 90° and a corner angle of 20° at a temperature of 473 K with a strain rate of 2 mm · s−1. The specimen was then processed with 1 to 8 passes by the route Bc method with 90° rotation. In the case of eight passes, the grain size was reduced to as small as 300 nm. As a result of the ECAP, the tensile strength was raised from 75 MPa to 134 MPa, while the electrical conductivity did not show a significant difference after eight passes. The thermal conductivity gradually decreased with ECAP passes, because of the decreased grain size by ECAP.
Highlights
Equal channel angular processing (ECAP) is a method of severe plastic deformation that enables a high level of strain without changes in surface area and is being used to refine grain size to a submicron or smaller level [1]
We found that the grains are more finely and homogenously formed with the increase of Equal channel angular pressing (ECAP), except that 1 pass and 2 passes had inhomogeneous structures
The thermal-conductivity results in Fig. 9 show that the difference between thermal conductivity values of the as-received and ECAP specimen were largely constant at room temperature and 100 ◦C, but the difference decreased after 200 ◦C
Summary
Equal channel angular processing (ECAP) is a method of severe plastic deformation that enables a high level of strain without changes in surface area and is being used to refine grain size to a submicron or smaller level [1]. The grain refinement of aluminum alloys below submicron size has been difficult due to the low-temperature recovery with a high stacking fault energy, but ECAP application enables a significant improvement [1]. Aluminum 1060 contains 99.6 % aluminum and slight amounts of silicon and iron as impurities. It is a common conductor among 1xxx alloys used as materials for power transmission or distribution systems. This study used ECAP on aluminum 1060 to refine its structure, and observed the strength with increasing passes; the mechanical properties of the refined structure; and the changes in thermophysical properties of ultrafine grained aluminum. Four-probe electrical-resistivity measurements were taken, and the electrical conductivity was calculated with the thermal conductivity using the Wiedemann–Franz method
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