Proposed Solution for Random Characteristics of Aluminium Alloy Wire Rods Due to the Natural Aging

Abstract

In the last 50 years in the worldwide market for power transmission cables, there has been a tendency to replace aluminium cables electrical grade (EC) with steel cables by fully aluminium alloy (AAAC). The advantage in using cable AAAC is mainly economic (least amount of support structures and maintenance), addition to the elimination of the problems of galvanic corrosion and improved abrasion resistance. In order to obtain better mechanical properties, respect to the pure aluminium, aluminium alloyed with magnesium and silicon (AA6XXX series) is used, which by a combination of cold working and heat treatment allows obtaining greater mechanical strength without affecting too much the electrical conductivity. In this development it has worked with AA6101/6101M alloy. The manufacturing of aluminium alloy wire rods for such applications, using the conventional process Properzi, requires heat treatment of solubilized, continuous or discontinuous (batch). During the waiting time of two months or more, the wire coils are exposed to natural aging at room temperature, entering into the wiredrawing machines with different mechanical properties. The wires obtained by the traditional method of manufacture in Argentina, through the wiredrawing, result in significantly higher mechanical properties, not complying with the standards. Furthermore many breaks occur mainly when a high tensile strength wire is processed for wire 2mm in diameter or less. In the proposed method, a part of the initial wiredrawing is replaced by cold rolling and a subsequent partial aging. The results obtained in this study allow us to conclude that in the proposed process better properties and mechanical integrity are achieved than the traditional process, maintaining the electrical conductivity.