Microstructural Studies on New Developed Niobium Cast High Speed Tool Steel

High speed tool steels, widely used for tools, are characterized of excellent hardness, wear resistance, and high temperature properties. These steels are used not only for metal cutting but also in wood, textile, and leather industries. As in cast and wrought materials, high speed tool steels show a broader application range compared to tool materials which are produced by powder metallurgy. However, the production from bulk material requires high machining costs in the case of specially formed tools. Here is discussed that a new alloying design with niobium differing from known high speed steel chemical alloying designs is created and the production of high speed tool steels in as cast condition without hot working. The microstructure is modified by adding niobium and applying proper heat treatment to get blocky type small monocarbides ending up with providing high toughness and preventing the eutectic carbides which are situated in the interdendritic areas and which increase brittleness between dendrites in the as-cast structure.