e microstructure, phase constitution, and hardness of Cr-V ledeburitic tool steel Vanadis 6 subjected to subzero treatment at −140°C and for different soaking times have been investigated. e light microscopy, scanning electron microscopy, and X-ray diffraction have been used for microstructural investigations. e hardness has been evaluated by the Vickers method. e obtained results assist to draw that subzero treatment reduces the retained austenite amount and increases the population density of carbides, compared to conventional heat treatment. e extent of decrease in the retained austenite amount makes around 85%, and the increase in population density of small globular carbides was approximately fivefold. High compressive stresses were identified in the retained austenite, and their values follow the increase in carbide count. is makes a serious support to the theory explaining the formation of "extra" carbides as a by-product of more complete martensitic transformation. As a result of the mentioned microstructural changes, the material hardness increased from 875 ± 16 HV 10 up to 954.6 ± 14 HV 10 for conventionally quenched and SZT steels, respectively.
The effect of cryogenic processing and tempering on selected mechanical properties and fracture micromechanism of Vanadis 6 high alloy cold work tool steel was analysed. The samples were processed in cold nitrogen gas at -140 °C for 48 h, and tempered at temperatures of 170 – 530 °C. It was found that the hardness of sub-zero treated Vanadis 6 steel decreases with increasing tempering temperature. The highest hardness of the specimen 960 HV10 was achieved by tempering at 170 °C and the lowest hardness 790 HV10 resulted from tempering at the highest tempering temperature, i.e. 530 °C. However, the hardness of conventional heat treated samples was less than 800 HV10 in full range of tempering temperatures. The fracture toughness of sub-zero treated samples does not differ from what was obtained by conventional heat treatment schedule except the case of the high tempering temperature of 530 °C where an increase in fracture toughness by approx.. 3 MPa.m1/2 has been recorded. The carbides differ clearly in their role in the fracture propagation. While the secondary carbides undergo easily cleavage the eutectic carbides assist more probably decohesive fracture propagation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.