The investigations were inspired with the problem of cracking of steel castings during the production process. A single mechanism

of decohesion – the intergranular one – occurs in the case of hot cracking, while a variety of structural factors is decisive for hot cracking

initiation, depending on chemical composition of the cast steel. The low-carbon and low-alloyed steel castings crack due to the presence

of the type II sulphides, the cause of cracking of the high-carbon tool cast steels is the net of secondary cementite and/or ledeburite

precipitated along the boundaries of solidified grains. Also the brittle phosphor and carbide eutectics precipitated in the final stage

solidification are responsible for cracking of castings made of Hadfield steel. The examination of mechanical properties at 1050°C

revealed low or very low strength of high-carbon cast steels.