The specimens, selected from different locations of as-cast 304 stainless steel slab, were annealed according to the temperature profiles, which simulated the industrial re-heating process before hot rolling. Annealing, following thermal cycles with maximum temperatures between 1230 and 1270 degrees C for a total time of 1 h, reduced the delta ferrite content, increased the size of the individual ferrite island and changed its shape to a more spherical one. An increase of annealing time to 1.5 h caused a drastic reduction in delta ferrite content and its further spheroidization. Moreover, the size of the individual ferrite islands was decreased. While after 1 h of annealing, the delta ferrite content depended on a particular thermal cycle and its maximum temperature; after a longer annealing time of 1.5 h, the delta ferrite content was very similar for all the thermal cycles applied. A statistical analysis of over 2200 industrial data, describing the slab chemical compositions and edge quality of the hot rolled plates was conducted. Generally, the alloying elements suppressing the delta ferrite formation improved the plate edge quality. In particular, carbon and nitrogen exerted the strongest influence, and the higher sum of both elements led to a lower probability of the edge cracking.