On the Influence of Cryogenic Steps on Heat Treatment Processes

Although treatments at cryogenic temperatures have been known for decades, these processes are still far from being common in industry. This can be blamed to a great extent on insufficient understanding of the permanent effects caused by low temperatures in the materials. Many of the applications of cryogenic treatments have been developed empirically, with little attention to the nature of the transformations generated in the materials. This often leads to inconsistent industrial results because the particularities of the different materials and the influence of previous treatments are hardly taken into account. Nevertheless, the consideration of these parameters is essential to adequately address the study of cryogenic treatments and their industrial implementation. Cryogenic treatments are operations that should be considered and analyzed as a part of the overall heat treatment scheme rather than as isolated actions. This study presents some examples that show the outcomes obtained in two steel grades by applying various combinations of heat and cryogenic treatments. It can be concluded that the way in which they are combined is determinant for the final performance (regarding hardness, toughness, corrosion resistance, etc.) obtained in each case.