Microstructure and Thermomechanical Properties of Magnesium Alloys Castings

Abstract

Microstructure and Thermomechanical Properties of Magnesium Alloys Castings Magnesium alloys thanks to their high specific strength have an extensive potential of the use in a number of industrial applications. The most important of them is the automobile industry in particular. Here it is possible to use this group of materials for great numbers of parts from elements in the car interior (steering wheels, seats, etc.), through exterior parts (wheels particularly of sporting models), up to driving (engine blocks) and gearbox mechanisms themselves. But the use of these alloys in the engine structure has its limitations as these parts are highly thermally stressed. But the commonly used magnesium alloys show rather fast decrease of strength properties with growing temperature of stressing them. This work is aimed at studying this properties both of alloys commonly used (of the Mg-Al-Zn, Mn type), and of that ones used in industrial manufacture in a limited extent (Mg-Al-Sr). These thermomechanical properties are further on complemented with the microstructure analysis with the aim of checking the metallurgical interventions (an effect of inoculation). From the studied materials the test castings were made from which the test bars for the tensile test were subsequently prepared. This test took place within the temperature range of 20°C - 300°C. Achieved results are summarized in the concluding part of the contribution.

Development of composite salt cores for foundry applications

“…The casting process using an increased pressure all the time represents the predominant technology for manufacturing the castings from non-ferrous alloys 3,4 (primarily the use of metal cores). With the growing shape complexity of the castings the requirements for the cleanability of pre-cast cavities and holes are escalating.…”

Mould Components Impact on Structure and Quality of Elektron 21 Alloy

“…The Mg alloys found a significant interest of aerospace and automotive industries as engine housings, transmission cases, gearbox housings etc [6,7]. The Mg-Al alloys exhibit good mechanical properties up to 150°C [8]. In higher temperatures the metastable Mg 17 Al 12 phase, occurring on the grain boundaries, starts to decompose [5,6,9,16].…”

“…In higher temperatures the metastable Mg 17 Al 12 phase, occurring on the grain boundaries, starts to decompose [5,6,9,16]. It leads to significant drop of mechanical properties at the elevated temperature [8]. The working temperature of the engine elements, even in their cold parts often exceed 150°C.…”

Thermophysical properties and microstructure of magnesium alloys of the Mg-Al type

“…These applica-tions require exploitation in operating conditions at a temperature of 150-200°C. Commercial magnesium alloys of the type AM and AZ do not have these properties, this is related to their poor mechanical properties at elevated temperatures, 5 and the cause is the low structural stability, and thus the creep resistance. Developments in this area brought about the introduction of new alloys, i.e., Mg-Al-Sr (AJ) and Mg-Al-RE (AE).…”