Vanadis 4 Extra

Abstract: In this study, the wear performance of cryogenically treated cold-work tool steel (Vanadis 4 Extra) samples was evaluated in the light of some sliding wear tests. For this purpose, the samples were cryogenically treated for different durations (0, 1, 12, and 24 h) at deep cryogenic temperature (–145◦C). A tempering process was performed at two different temperatures (175 and 525◦C) for 2 h. The wear experiments were carried out in a ball-on-disk tester, by applying two loads of 10 and 20 N and a sliding velocity of 0.3 m s−1. Experimental results showed that samples treated for 24 h and tempered at 525◦C exhibited the best wear performance. This can be explained by the increasing hardness value as a result of the nearly full transformation of retained austenite to martensite, the formation of fine carbide particles and homogeneous distribution of carbides. The hardness measurements and XRD analysis confirmed the wear test results. K e y w o r d s: Vanadis 4 Extra, cryogenic treatment, microstructure, wear resistance

Abstract: Powder steels Vanadis 4 Extra, Vanadis 6 and Vanadis 10 with different contents of V, Cr and Mo are studied after 180-min nitriding at 570°C at nitrogen potential KN = 2 and 10. The resistance of the steels to abrasive wear and the Vickers hardness of the surface layers are determined. An x-ray diffraction analysis is performed. Nitriding modes raising the endurance of tools from the powder steels are suggested.

Abstract: In this work, a highly alloyed cold work tool steel, Uddeholm Vanadis 4 Extra, was manufactured via the electron beam melting (EBM) technique. The corresponding material microstructure and carbide precipitation behavior as well as the microstructural changes after heat treatment were characterized, and key mechanical properties were investigated. In the as-built condition, the microstructure consists of a discontinuous network of very fine primary Mo- and V-rich carbides dispersed in an auto-tempered martensite matrix together with ≈15% of retained austenite. Adjusted heat treatment procedures allowed optimizing the microstructure by the elimination of Mo-rich carbides and the precipitation of fine and different sized V-rich carbides, along with a decrease in the retained austenite content below 2%. Hardness response, compressive strength, and abrasive wear properties of the EBM-manufactured material are similar or superior to its as-HIP forged counterparts manufactured using traditional powder metallurgy route. In the material as built by EBM, an impact toughness of 16–17 J was achieved. Hot isostatic pressing (HIP) was applied in order to further increase ductility and to investigate its impact upon the microstructure and properties of the material. After HIPing with optimized protocols, the ductility increased over 20 J.