DRY SLIDING WEAR STUDIES ON SINTER-FORGED Fe-Cu-C-xMo ALLOYS

Abstract

Fe-Cu-C system is 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. Molybdenum enhances hardenability by providing solid solution strengthening. So, the mechanical properties of ferrous alloys are improved by addition of molybdenum. In this present investigation, an attempt is to find the effect of molybdenum content and compare the results with plain carbon steel. Fe-2Cu-0.7C with 0, 0.5 and 1.5 percentage of Mo was prepared by using a mixture of Ferro-molybdenum powder, and elemental powders of iron, copper and carbon. The powders are mixed and blended initially in a double cone mixture to yield the alloy powders of Fe- 0.7C, Fe-2Cu-0.7C, Fe-2Cu-0.7C-0.5Mo and Fe-2Cu-0.7C-1.5Mo. These alloy powders are sintered at 1150ºC for 30 minutes in a reducing atmosphere of 90% nitrogen and 10% hydrogen gas. The sintered components are hot forged immediately at 1150ºC. Again the components are re-forged twice at the same temperature to reduce the porosity content. The forged components are homogenized at 1250 ºC for 4 hours. In addition, samples are heat treated in normalized and quench tempered condition to study the mechanical properties. Mechanical properties were significantly influenced by the addition of Mo as well as with heat treatment conditions. The microstructural study showed mostly ferrite, pearlite and bainite structure in furnace cooled condition whereas a complex microstructure of tempered martensite was observed in the fast cooling condition. Also, with addition of molybdenum grain refinement was also observed. Also, dry sliding wear behavior in normalized, quench and tempered heat treated conditions was studied. Study of wear behavior delineates a complex mechanism of wear (delamination, abrasion and oxidation) in Fe-2Cu-0.7C-xMo alloy depending of the amount of Mo added as well as on heat treatment conditions.