The book is devoted to the complex modelling of the microstructural alteration during hot metal forming with controlled cooling – the so-called Thermomechanical Treatment (TMT) and its influence on the mechanical properties of the final product. The simulation of the total thermomechanical schedule is realized using non-formal approaches and is computerized by the Finite Element Method. The application of this technique leads to reliable basis for realistic prediction and ruling of the steel and aluminium alloys treatment. In this way using of Computer Aided Simulation (CAS) is becoming necessary in the area of multipurpose design of metallurgical processes.