Modulus of Rupture Evaluation on P/M Cold Worked Tool Steels Submitted to Gas Nitriding

Abstract

Cold work tool steels have been successfully applied for decades. Modern Powder Metallurgy (P/M) techniques are considered important for tool steels in general since high alloy projects could be development. An important example is P/M cold work tool steel X 220 Cr Mo V 13 4. Although tribological properties are quite important to be studied, mechanical properties are also relevant since tools are submitted to high static and dynamic loads. Present work has investigated the effect of gas nitriding process on modulus of rupture, in modem cold work tool steel above mentioned. Nitriding process applied has affected mechanical properties significantly, reducing by 30 % of modulus of rupture decreasing obtained from 4-point bending test. The high C content of those modern steels induces e mono-phase composition in compound layer. Although e nitride, due to its high strength, increases some tribological properties, ductility of those tool steels is clearly affected.