Structure and properties of cast alloy AK7 after thermomechanical hardening

Thermomechanical treatment significantly increases many mechanical characteristics and complicates intercrystalline destruction of wrought aluminum alloys. At the same time, there are practically no data available in the literature on the use of such a treatment to improve the complex of properties of cast aluminum alloys. The interest in the processes of hardening of cast aluminum alloys is due to the desire to increase the strength characteristics of cast products, reduce their weight and cost, and increase the reliability and durability of the entire structure. At the same time, an increase in the operational reliability of cast products should be based, inter alia, on the improvement of technological methods for their production and processing. This paper presents the results of studying the thermomechanical parameters of the AK7 casting alloy on a plastometer, as well as data on the effect of different modes of thermal and thermomechanical treatment on the structure, properties and stability of the hardened state of this alloy. The studies carried out show that the complex of properties of the AK7 casting alloy can be improved by using thermomechanical treatment. At the same time, low-temperature thermomechanical treatment (LTMT) significantly increases the strength properties of the AK7 alloy with a noticeable decrease in plasticity. Warm deformation is preferable to cold deformation as it provides the best set of mechanical properties. Note also that the use of LHMT significantly reduces the aging time of the alloy. In contrast to HTMT, high-temperature thermomechanical treatment (HTMT) leads to noticeably less hardening of the alloy, but it provides an increase in plasticity and, as a consequence, a decrease in the tendency of the alloy to brittle fracture.