In an attempt to understand how and where dislocations are introduced into Si ingots bytemperature gradients, bulk dislocation-free FZ crystals are exposed to temperature gradients similar tothose in Bridgman Si crystal growth. This heat treatment introduces dislocations, which were analyzedusing X-ray topography (XRT) and Scanning InfraRedPolariscopy (SIRP). Hereby, the orientationdependency is taken into account and ingots in (001) and (111) growth orientation are evaluated inthis work. It can be found that the dislocation generation takes place at similar regions of the crystaland is independent of orientation, however, their propagation and multiplication differs. This leads toan overall different shape of the dislocation network. Especially intriguing are the long slip lines inthe (111)-crystal, which cannot be found in the (001)-crystal. This suggests a different magnitude ofslip propagation depending on the sample orientation. This effect should be explained by a differentactivation of slip systems and is discussed in the paper.