PROCESSING OF Fe-Cu-C BY POWDER FORGING

Abstract

Fe-Cu-C system is one of the most commonly used ferrous alloy system in ferrous powder industry and finds a wide range of applications in automobile industry due to its superior mechanical properties, sinterability, and competitive cost. In recent times use of such components in applications like gears where high fatigue performance is required has increased. Present study investigates the effect of molybdenum on the properties of powder forged Fe-Cu-C alloy. Fe-2Cu-0.65C with varying Mo content from 0.25 - 4% (0.25, 0.5, 1.0, 1.5, 2.0, 4.0 wt %) were prepared by using a mixture of ferro-molybdenum powder, and elemental powders of iron and copper, and carbon. Carbon was added in form of graphite. The powders were mixed in suitable proportions to get the desired composition, uniaxially pressed in a hydraulic press at a pressure of 500 MPa and sintered at 1120°C for 40 minutes in a reducing atmosphere of 80% nitrogen and 20% hydrogen gas. The sintered compacts were hot forged at 1120°C and homogenized at a temperature of 1300°C for 2 hours. Following homogenization treatment, the specimen were austenitized in reducing atmosphere and cooled using different cooling rates (water quenching, oil quenching, air cooling and furnace cooling) to study the effect of cooling rate on the specimen containing molybdenum. Mechanical properties of the specimens were determined using tensile test and hardness test. Micro-structural characterization of the samples was carried out with the help of optical microscopy and SEM analysis. Various phases in the compacts and powder samples were identified with the help of XRD technique. Improvement in mechanical properties was observed with the addition of molybdenum to the base Fe-Cu-C system.