Microstructure and Properties of Al-Mg-Si Wire-Rod Subjected to Continuous Heat Treatment

Abstract

Among multiple applications 6XXX-series aluminum alloys are widely used as electrical conductor for overhead power lines. For that application Al-Mg-Si alloys are produced mainly in the form of wire rod in the continuous casting and rolling lines (CCR). There is many technological routes possible to transform the Al-Mg-Si wire-rod into precipitation hardened, ready to use Al-Mg-Si wires. One of these routes involves using the heat of continuous casting and rolling process to artificial ageing of wire-rod, which is motivated by ecological premise. In the current paper the results of continuous heat treatment of the wire-rod within the CCR line (involving quenching of the alloy to artificial ageing temperature) on the microstructure and properties has been examined. It was shown the structure of wire rod formed in such process is very irregular. TEM investigations has shown that many heterogeneous particles are present and the arrangement of the β main hardening phase is very inhomogeneous with wide precipitate free zones occurred. However this type of microstructure has a positive effect on electrical properties of the material in question, which is important taking into consideration application of the alloy.