Le Chatelier diagrams may be adopted for the definition of thermodynamic loci of explosion in terms of internal energy with respect to the temperature for either the primary explosion or for the deflagrative, post-combustion of the products of the first reaction with air, the afterburning reaction. In this paper, Le Chatelier diagrams are produced for TNT and black powder by using the CEA code. Pressure plots with respect to density or air/fuel ratio are also shown. These results are useful for the simulation of explosion (hydrodynamic codes), and more generally for the definition of safety of storage, transportation, and production of explosives and pyrotechnics. Furthermore, the method can be easily extended to any deflagrative pyrotechnic substances, for which information on explosion and afterburning effects are needed.