Influence of deep cryogenic treatment routes on the mechanical behaviour of a Cr-Mo-V hot work tool steel

Cryogenic treatments have shown a remarkable potential for improving the in-service performance of many tool steels despite the lack of knowlerge to which this technology is associated and the poor understanding of its metallurgical fundamentals. The type of cryogenic treatment used and its position in the heat treatment sequence have a determinant influence on the final properties, making evident the need of considering the cryogenic steps as an integrated part of the whole heat treatment sequence, instead of just an add-on process. This study, conducted on a Cr-Mo-V tool steel, shows how different treatment sequences lead to different mechanical properties (harness, impact resistance, etc.). the influence of deep cold temperatures in the tmpering behaviour and the tempering brittleness phenomenon has also been analyuzed as wel as their effect on the microstructure and the corrosion behaviour of this steel. Some basic clues about how to choose the right cryogenic treatment route depending on the desired performance and from industrial point of view are given.