Papers by Author: Beata Smyrak

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.

Abstract: The Al-Mg-Si alloys, due to their unique combination of lightweight, mechanical and electrical properties and excellent corrosion resistance, are used as a material for the production of overhead power conductors, commonly known as AAAC (All Aluminium Alloy Conductor). Wires intended for conductor manufacturing are obtained from the wire rod produced by a continuous casting and rolling line (CCR, e.g., Continuus-Properzi). The Al-Mg-Si wire rod can be processed into ready-made wires by different technological routes, which mainly consist of different combinations of strain hardening as well as precipitation hardening of wire rod or wires. In Europe the conventional technological route comprises solution heat treatment of wire rod coils (heated at temperatures over ~500 °C, followed by quenching into water), then natural ageing of wire rod at ambient temperature for a couple of days, next wire drawing, and finally artificial ageing.This paper discusses results of investigations on developing an alternative technological route. In this process heat from the continuous casting and rolling process by Continuus-Properzi is used for heat treatment of the wire rod. The new technological route allows the abandonment of the high temperature heat treatment as well as natural ageing of the wire rod, making the production process less energy consuming, cheaper and faster than the conventional one. The current paper presents research results identifying the structure of materials from different Al-Mg-Si wires production process routes. It also focuses on electrical and mechanical properties.

Abstract: This paper discusses the most current issues of overhead power transmission relative to the development of new conductive materials with unconventional technological and operational qualities. The present condition is based on the one hand on the traditional aluminium-steel conductors with their numerous weaknesses, and on the other hand on state of the art design solutions employing self-supporting, highly-conductive, and thermally and rheologically resistant aluminium alloys. A gap exists between pure aluminium-based conductors which are no longer sufficient and conductors made of precipitation hardened aluminium alloys, which even though they allow to achieve perfect properties, they are not sufficiently cost-effective as for their complex manufacturing technologies. For these reasons, light and sufficiently strong materials based on aluminium are needed, which enable simplified technologies for processing into conductors. Non-precipitation hardened aluminium alloys with such alloy additives as Fe, Si, Cu, Mg, Ti, B, and rare earth metals are preferred in this area. An appropriate composition of these elements, as well as manufacturing and alloy production technology (casting, rolling and drawing) create potential opportunities to obtain wires and conductors with application properties required by electrical power engineering. This paper thoroughly analyses the impact of various elements on the formation of mechanical and electrical properties of aluminium alloys.

Abstract: Eight hypoeutectic aluminium alloys with iron content within the range of 0.07-1.09% by weight, were examined. The structure, the mechanical and electrical properties of wires used for electrical purposes were studied. The batch material for the drawing process was wire rod obtained from the continuous casting and rolling line by Continuus-Properzi method. It has shown a linear relationship between mechanical properties of wire rod, a higher plasticity of wire after drawing process and an increase in thermal resistance of the material with increasing iron content. The findings enable to draw conclusions of basic and application characteristics, pointing to the possibility of using aluminium with higher iron content in the wire drawing process of small diameter and microwires for the production of automotive bundles, accumulator cables and winding wires.

Abstract: The paper focuses on 6xxx series AlMgSi conductor alloys. Such alloys are used for manufacturing of conductors for power transmission. Since the most current standards define as many as seven types of wires with various mechanical and electrical specifications, the existing philosophy of AlMgSi wires manufacturing technology for electrical applications has to be revised. Strength specifications of precipitation hardened AlMgSi alloys may be enhanced by strain and by precipitation hardening. Therefore from the scientific point of view identification seems to be relevant of the impact of the sequence of these mechanisms on development of final wire properties. In particular, this paper tries to answer the following question: Does the sequence of hardening mechanisms affect the development of mechanical properties of AlMgSi alloy wires The paper presents results of a study of the impact of artificial ageing parameters of 6201 grade AlMgSi alloy wires on their final properties. The study results are presented and discussed in two parts. The first part addresses the impact of artificial aging temperature and duration on the strength properties of AlMgSi (grade 6201) alloy wire rod. The second part is focused on hardening development in the process of drawing of a AlMgSi wire made of the same alloy grade, subjected to different thermal treatments, the parameters of which have been selected based on analysis of the results of the first, wire-rod related, part of the study.