The research on rolling mills cylinders durability in exploitation experimentally defines an important chapter from the thermal fatigue of the organs Of machines in the movement of rotation, in variable temperature mediums, and the mathematical molding establishes a methodology for the determination of the technological parameters values, for which a mechanical characteristic (the hardness) has the desirable values. The technological manufacturing process of the rolling mills cylinders, as well as the quality of material used in manufacturing them, can have a different influence upon the quality and the safety in the exploitation. Our proposal approaches the issue of quality assurance of the rolling mills cylinders, from the viewpoint of the quality of materials, which feature can cause duration and safety in exploitation. The experimented durability research, as well as the optimization of the manufacturing technology, allows the conclusion of direct results for the rolls, The beneficiaries of these results are the unit in which the rolls are manufactured, as well as the unit that exploits them. The research on the durability in exploitation of hot rolling mill cylinders represents an important scientific and economical issue. The study represents a detailed approach of the influence of some technological factors on the durability in exploitation of rolling mill iron cylinders and suggests solutions meant to increase the durability of the rolls in exploitation.