Effect of Duration of Deep Cryogenic Treatment on Microstructure and T ensile properties of 1.2542 tool steel

Two groups of tool steel properties, namely high hardness and high toughness, are important for the performance of tool steels. Any increase in hardness occurs at the expense of reduced toughness. Deep cryogenic treatment may be used for increasing toughness, strength and hardness simultaneously. 12 sets of 1.2542 tool steel specimens that 9 of which have been deep cryogenically treated for 24, 36, and 48h at -196 oC and have been tempered for 1, 2, and 3h at 200 oC and then double deep cryogenic treatment has been done. 3 sets were selected as standard specimens (control specimens). The best results, simultaneous improvement of 13.8% in toughness, 8.5% in hardness, 26.4% in tensile strength and 23.4% in yield strength were obtained for the specimen treated at -196 oC for 36 hours and then tempered at 200 oC for 1 hour (specimen 361).