Effect of cryogenic treatment holding time on mechanical and microstructural properties of Sverker 21 steel

Abstract This study investigated the effects of shallow and deep cryogenic treatment on the microstructural and mechanical properties of Sverker 21 tool steel. After conventional heat treatment, shallow cryogenic treatment at −80 °C for 2, 12, and 24 h and deep cryogenic treatment at −180 °C for 2, 18, and 36 h were applied on the steel samples. After that, the samples were tempered at 200 °C for 2 h. As a result of these treatments, the steel samples’ hardness, toughness, and wear rate changes were determined, and their microstructural properties were investigated. As a result of the study, it was observed that the cryogenic treatment had positive effects on the mechanical and microstructural properties of Sverker 21 steel. Mechanical properties also improved with increasing holding time for both cryogenic treatment types. It has been found that the deep cryogenic treatment provides better mechanical properties compared to the shallow cryogenic treatment. The maximum hardness and wear resistance were obtained in the deep cryogenically treated sample for 36 h. Compared to the CHT sample, the hardness and impact energy of the DCT(36) sample increased by approximately 11.75% and 17.36%. An improvement of approximately 64% was observed in the wear rate.