Microstructure of castings made of magnesium alloys based on recycling of the circulating scrap

The increase in the use of magnesium alloys in industry has caused the growth of recycling of a great number of recyclable materials to be exploited. Therefore, recycling of the circulating scrap is getting a high priority technological issue. It is well known that this issue is really tough because of a considerably high reactivity and susceptibility of these alloys to fire up, already below melting temperature. However, recycling of the circulating scrap is essential because, on the one hand, the standards legislation is being tightened up and the foundry running costs have to be reduced, on the other hand. In this study, the influence of the circulating scrap addition on the microstructure and mechanical characteristics of castings obtained with certain scrap addition has been presented. A positive effect of the circulating scrap addition on the strength of tested alloys has been identified. Castings comprising circulating scrap addition have shown the higher ultimate tensiles strength (153 MPa for the scrap percentage of 75%), in comparison to pure ingots (128 MPa). The circulating scrap addition has also caused the increase in hardness of the obtained castings, however, only in case of its low contributions (~80 HB for the circulating scrap addition of 25% and 50%).