The effect of vanadium microaddition on the strength of low-carbon cast steel containing 0.19% C used, among others, for castings of slag ladles was discussed. The tested cast steel was melted under laboratory conditions in a 30 kg capacity induction furnace. Mechanical tests were carried out at 700, 800 and 900°C using an Instron 5566 machine equipped with a heating oven of  2C stability. Non-standard 8- fold samples with a measuring length of 26 mm and a diameter of 3 mm were used for the tests. It has been shown that, compared to cast steel without vanadium microaddition, the introduction of vanadium in an amount of 0.12% to unalloyed, low carbon cast steel had a beneficial effect on the microstructure and properties of this steel not only at ambient temperature but also at elevated temperatures when it promoted an increase in UTS and YS. The highest strength values were obtained in the tested cast steel at 700C with UTS and YS reaching the values of 193 MPa and 187.7 MPa, respectively, against 125 MPa and 82.8 MPa, respectively, obtained without the addition of vanadium. It was also found that with increasing test temperature, the values of UTS and YS were decreasing. The lowest values of UTS and YS obtained at 900°C were 72 MPa and 59.5 MPa, respectively, against 69 MPa and 32.5 MPa, respectively, obtained without the addition of vanadium.

Monitoring the solidification process is of great importance for understanding the quality of the melt, for controlling it, and for predicting the true properties of the alloy. Solidification is accompanied by the development of heat, the magnitude of which depends on the different phases occurring during solidification. Thermal analysis is now an important part of and tool for quality control, especially when using secondary aluminium alloys in the automotive industry. The effect of remelting on the change of crystallization of individual structural components of experimental AlSi9Cu3 alloy was determined by evaluation of cooling curves and their first derivatives. Structural analysis was evaluated using a scanning electron microscope. The effect of remelting was manifested especially in nucleation of phases rich in iron and copper. An increasing number of remelts had a negative effect after the fourth remelting, when harmful iron phases appeared in the structure in much larger dimensions.