Influence of Strain Hardening and Precipitation Sequences on the Mechanical and Electrical Properties of Al-Mg-Si Alloy Wires

In the contemporary era of energy transition, energy infrastructure assumes a pivotal role in ensuring the reliable and efficient transmission of electricity over long distances. The increasing use of renewable energy sources and the growing demand for electricity necessitate the modernisation and optimisation of overhead transmission lines. In this context, AAAC (All-Aluminum Alloy Conductor) overhead conductors represent a highly effective solution, as they are manufactured from high-strength, high-conductivity aluminium alloys belonging to the Al-Mg-Si system. In comparison with traditional ACSR conductors, AAAC conductors are characterised by their reduced weight, enhanced corrosion resistance, and superior electrical performance, a consequence of the absence of a steel core. The utilisation of precipitation-hardening Al-Mg-Si alloys facilitates a favourable combination of high electrical conductivity and increased mechanical strength. The raw material for wire production is wire rod manufactured on a Continuus Properzi continuous casting and rolling line in the T1 condition. The final properties of the wires are achieved through a carefully controlled sequence of heat treatments, including high-temperature homogenisation and solution annealing, followed by low-temperature precipitation hardening. This study examined the impact of the sequence of precipitation hardening and strain hardening processes on the electrical and mechanical properties of EN AW-6101 alloy wires. The drawing process was executed in accordance with the following sequence: 9.50 mm – 8.30 mm – 7.25 mm – 6.90 mm – 6.00 mm – 5.60 mm – 4.85 mm – 4.40 mm – 3.88 mm – 3.50 mm – 2.90 mm. During the wiredrawing process, the wires with diameters of 7.25 mm, 6.00 mm, 4.85 mm, 3.88 mm, and 2.90 mm were subjected to artificial ageing at three temperatures (100°C, 140°C, and 160°C) for a duration of 4 hours. The sequential drawing and artificial ageing processes resulted in wires with a final diameter of 2.90 mm achieving electrical conductivity within the range of 31.05–34.25 MS/m. Concurrently, these wires exhibited tensile strengths within the range of 360–425 MPa. The findings of the present study demonstrate that the sequence and parameters of the ageing and drawing operations exert a substantial influence on the kinetics of dislocation precipitation and dislocation density. The optimisation of the sequence of these processes enables the production of wires characterised by both high tensile strength and high electrical conductivity, which is essential for modern, high-performance transmission lines.