Study of effects of deep cryotreatment on mechanical properties of 1.2542 tool steel

摘要

Normally, increase in strength and wear resistance of tool steels is associated with a reduced ductility. However, deep cryotreatment (DCT) may be used to simultaneously increase tensile strength and hard ness and improve ductility of tool steels. In this work, effects of different DCT cycles on mechanical prop erties of 1.2542 tool steel have been studied. Three sets of specimens were investigated: two sets of untreated specimens, for studying the effect of some hardening parameters on the metal properties, and a third set consisting of cryotreated specimens. Soaking and tempering temperatures were kept con stant at -196 ℃ and 200 ℃, respectively. Different cryotreatment cycles were implemented by varying soaking time (24, 36 and 48 h) and tempering duration (60, 120 and 180 min). In order to ensure opti mum treatment conditions, time gaps between various treatment steps were kept to minimum. Results show that two cryotreatment cycles consisting of: (ⅰ) 36 h soaking at -196 ℃ and 1 h tempering at 200 ℃, and (ⅱ) 48 h soaking at -196 ℃ and 2 h tempering at 200 ℃ produce the best effects in the cryo treated 1.2542 tool steel specimens, namely 32-36% increase in tensile strength, 9-12% increase in hard ness, and 12-35% improvement in ductility.