Tool steels are used in a wide variety of applications, including forming, shearing, cutting and casting ( tool, die and mold manufacturing) where (because of their outstanding properties) high wear resistance, hardness, strength, toughness, heat resistance and other properties are preferred for optimal performance. In addition to alloy, tool steels are considered special because they are very difficult to manufacture and require careful manufacturing at each processing stage. The very high alloy content and special microstructure that make them desirable for severe applications also make them difficult to manufacture [ , ]. High carbon and high chromium tool steels (AISI D series) for cold working are among the main groups of tool steels. which stand out for their high wear resistance and exceptional non-deformation properties. The excellent wear resistance of Type D cold work tool steels is a result of their high chromium (~12 wt%) and carbon (1.5 to 2.35 wt%) contents. . Generally, high carbon and high alloy tool steels are particularly difficult to process through the conventional route of ingot metallurgy. The main challenge is that the relatively slow cooling of the conventional static casting ingot allows the formation of coarse eutectic carbide structures, which are difficult to break during hot working [1, ]. To overcome these problems, new processing methods such as powder metallurgy (PM) and spray forming have been developed for the production of the most highly alloyed tool steels, such as high carbon steels, to high chromium content (AISI D series) and high speed (AISI T and M series) [1, , , ]. These techniques offer the possibility of producing steels with greater homogeneity, an absence of segregations, a finer microstructure and a d...... middle of paper ...... Li, Effect of the modifying agent Ca-Si on the granulation of γ Eutectic + (Fe, Mn) 3C particle in an austenitic steel, Journal of Materials Science, Vol. 39, No. ?, pp. 1527-1530, 2004.BA Migachev, Effect of niobium on the mechanical properties of 9Kh2MF steel, used for the manufacture of forming rolls, Metal Science and Heat Treatment, Vol. 43, n° 3-4, pp. 103-106, 2001.X. Zhi, J. 62, n° 6-7, pp. 857-860, 2008.D. Li, H. Lin, H. Chen, Study of hypereutectic high chromium cast iron containing niobium, Mater Mech Eng, Vol. 6, no?, pp. 13-6, 1993.S. Kheirandish, A. Noorian, Effect of niobium on microstructure of cast AISI H13 hot work tool steel, Journal of Iron and Steel Research, International, Vol. 15, no. 4, pp... 61-66, 2008.