The article deals with the heat treatment and forging of AISI 321 austenitic stainless steel with a combination of the main alloying elements, Cr-Ni, in the mass ratio of about 18 : 10 and its variants used in the energy industry. The experiment was focused on the influence of heat treatment and thermomechanical processing on the microstructure and, especially, on the distribution of titanium carbo/nitrides and their agglomerations. Three experimental heats with various amounts of carbon, titanium and boron were prepared and subjected to different heat-treatment regimes. Also, different solution-annealing treatments were applied after the forging. The distribution of titanium carbo/nitrides was analyzed in different areas of the tested ingots. The microstructure of the samples was analyzed by means of light and scanning electron microscopy. A numerical simulation in the DEFORM HT software was used for simulating the cooling in different environments after the forging.