Effect of molybdenum addition on the mechanical properties of sinter-forged Fe-Cu-C alloys

摘要

Molybdenum provides solid solution strengthening, enhances hardenability and has thus been used to improve mechanical properties of ferrous alloys significantly. The present study reports the effect of molybdenum addition on the properties of sinter-forged Fe-Cu-C alloys prepared using elemental powders under various heat treatment conditions. The elemental powder mixtures were compacted at a pressure of 500 MPa followed by sintering at 1120 degrees C in N-2-20% H-2 atmosphere. Further, the sintered compacts were immediately forged at the sintering temperature in a closed die. The sinter-forged compacts were further homogenized and then heat treated under different cooling rates. Enhancement of the mechanical properties (hardness and tensile strength) were observed with Mo addition and increase in severity of quench. Hardness of air cooled samples was slightly lower than that of the water quenched samples but comparable with oil quenched samples. However, no significant increase in hardness was observed beyond 1.5 wt% Mo addition for all cooling conditions. At higher molybdenum content ductility was retained due to stabilization of ferrite phase by molybdenum. The microstructural study showed mostly ferrite-pearlite structure in furnace cooled condition whereas a complex microstructure was observed in the faster cooling conditions. Grain refinement was also observed with molybdenum addition. (C) 2015 Elsevier B.V. All rights reserved.