Refinement of α-Mg solid solution grains has a significant influence on the improvement of mechanical properties of cast magnesium alloys. In the article, the effects of three modifiers on microstructure and properties of AZ91 magnesium alloy casted to a sand mould were described. Overheating, hexachloroethane and wax-CaF2-carbon powder were applied. The research procedure comprised microstructure analysis by means of light microscopy, scanning electron microscopy and quantitative analysis with AnalySIS Pro® software and mechanical properties’ investigation. The microstructure of AZ91 alloy in the as-cast condition consists of α-Mg solid solution with precipitates of Mg17Al12, Mg2Si and Al8Mn5 phases. It was reported that all applied modifiers cause refinement of α-Mg solid solution grains and a decrease of the volume fraction of α-Mg+Mg17Al12 compound discontinuous precipitates. The best results were obtained in the case of wax-CaF2-carbon powder.

Magnesium alloys with rare earth (RE) elements addition, modified with zirconium are used for cast, light-weight solutions for components applied at temperature up to 250–300 °C. Computational methods are often used by the foundries to decrease the cost of a new product start-up. The commercially available magmasoft software is widely used to simulate a casting process. Nevertheless, its database does not contain complete data for modern alloys. We present the results of our investigations on the thermo-physical properties of a EV31A magnesium alloy and the simulation of a sand casting process with applied data. We compared the simulation and technological trials, recognized problems occurring during the simulation, and applied corrections. Our final simulations gave acceptable results. The differences between the technological tests and the simulation were caused by factors that are difficult to model in the simulation, such as the presence of nonmetallic inclusions and the degree of modification of the liquid alloy.

No abstract

We investigated the impact of the applied cooling and feeding method on the microstructure and metallurgical quality of castings made from WE43 magnesium alloy. Six identical plates with dimensions of 100×50×20 mm were sand cast for use as samples. Each casting was fed and cooled in a different way. The solid solution grain size was evaluated quantitatively using the Met-Ilo software program, and casting defects were observed using a scanning electron microscope Hitachi S3400N. The finest solid solution grain was observed in the castings with only the coolers applied. Non-metallic inclusions were observed in each plate. The smallest shrinkage porosity was observed in the castings with feeders applied.Keywords: WE43 magnesium alloy, sand casting, microstructure, quantitative evaluation, feeding and cooling method Celem badań było zbadanie wpływu zastosowanej metody chłodzenia i zasilana na mikrostrukturę i jakość metalurgiczną odlewów wykonanych ze stopu magnezu WE43. Sześć identycznych płyt o wymiarach 100×50×20 mm, chłodzonych i zasilanych na różne sposoby, odlano do formy piaskowej. Wielkość ziarna roztworu stałego zostały wyznaczone ilościowo w programie Met-Ilo. Obserwacje wad odlewniczych prowadzono na skaningowym mikroskopie elektronowym Hitachi S3400N. Najmniejszym ziarnem roztworu stałego charakteryzowały się odlewy z zastosowanymi tylko ochładzalnikami. W strukturze każdego z odlewów stwierdzono wtrącenia niemetaliczne. Najmniejszą porowatością skurczową charakteryzowały się odlewy z zastosowanymi nadlewami.

Magnesium alloys are widely used in automotive and aerospace industries due to their great connection of low density and good mechanical properties. They are also characterized by good castability and weldability. Their weak high temperature properties and corrosion resistance, led to development of magnesium alloys containing rare earth elements. Casting is the most popular way of manufacturing magnesium elements. However, there is a lack of investigations concerning impact of different factors on fluidity of these alloys. This paper presents results of investigations on influence of pouring temperature on castability and microstructure of QE22 and RZ5 magnesium alloys. In case of QE22 alloy, the filling length of the liquid alloy increased with the increasing pouring temperature. In RZ5 no such dependence was noted. This is probably caused by oxide films in the structure of material. Grain refinement and eutectics volume fraction also didn’t present correlation with pouring temperature.