Warm forming of 7075 aluminum alloys

The paper presents forming results of the drawpiece made of T6 temper 7075 aluminum alloy. The development of new, state-of-the-art forming methods by scientific and research centers is mainly driven by increasing demand for lightweight construction materials characterized by superior mechanical properties. As an example, new forming methods of aluminum alloys are being successfully implemented for many years in various fields of the industry. In recent years aluminum and its alloys gained in importance as a particularly useful construction materials. It is mainly motivated by two factors: on the one hand, a small density of aluminum alloys, on the other hand, the continuous development of material properties allowing to improve forming methods of end products. It is worthy to note that manufacturing of end products made of aluminum alloys, particularly alloys for plastic forming, encounters a number of problems limiting forming processes. The aim of the study was to analyse the warm forming process of a bracket made of T6 temper 7075 aluminum alloy. Microhardness of produced bracket has been tested and stress-strain curves of selected bracket areas have been determined. Obtained results were compared with nominal properties of the material. It is not possible to achieve the initial strength of the material after stamping of T6 temper 7075 aluminum alloy at 240 °C. Material after forming in such condition is characterized by 520 MPa ultimate strength. This result is significantly worse than the initial strength of the T6 temper 7075 alloy (equal to 580 MPa). Because 7075 aluminum alloy is a precipitation-hardened it is impossible to obtain high strength after forming without additional processes, ie. solutionizing and artificial aging. From an economic point of view, it is unprofitable because of time- and energy-consuming production, resulting in high price of the end product. The elevated forming temperature, ie. 240 °C, increases material plastic properties.