Solid particle erosion of an Fe-Fe3C metal matrix composite

The erosion resistance and morphology of spheroidized Fe-C alloys containing 0.2 to 1.4 wt pet carbon was investigated. The Fe-C alloy system was chosen as a model metal-matrix composite for the study of the effect on erosion of a hard second phase in a ductile matrix. Alloys were austenitized and water quenched to form martensite, then tempered at 690 degrees C for different times to produce carbide sizes of 0.4, 0.8, 1.6, and 2.4 mu m. Utilizing these materials, it was found that the erosion resistance increased as the microstructural features decreased in size, with the important microstructural variables being carbide spacing and ferrite grain size. These variables control dislocation motion in the ferrite and, in turn, affect the plastic deformation and the erosion resistance of the spheroidized alloys. For the 0.4 to 1.4 pet C alloys, the carbide spacing was sufficient to determine erosion rate, whereas, for the 0.2 pet C alloys, ferrite grain size became the controlling structure. Microstructural spacing, which is a measure of the mean free path between both the grain boundaries and the carbides, was found to describe all of the erosion data. A Hall-Petch-type relationship was found between microstructural spacing and both erosion rate and hardness.