Continuous cast slabs have many quality features like non-metallic inclusions and cracks at the surface. Fine cracks at the edge of the slab are made responsible for the ''Randschale''. In this regard the proeuktoide ferrite, which is formed during the gamma - alpha transformation, plays an important role during crack formation. When mechanical strain is applied, the thin ferrite films represent potential crack paths. The question comes up, how this situation is additionally negatively influenced for edge cracking by finest precipitations of aluminum nitride (AlN) at the austenite grain boundaries. In this work the influence of AlN to the corner crack sensivity at high temperatures is investigated on a conventional construction steel. For that hot tensile test on round specimens with different heat treatment has been carried out. The precipitation behaviour has been studied at the former austenite grain boundaries in some selected hot tensile specimen by transmission electron microscopy (TEM). Selective dissolution analysis of AIN have been realised at selected samples. The precipiatation kinetics of AlN have been numerically simulated using two software programs and the results have been compared. Due to the results obtained from hot tensile tests and the TEM investigations no exclusive influence of AlN on corner crack formation could be found.