Investigation Of Properties And Forming Mechanism Of Graded Structure Of Heavy Cross-sectional WC_p/Fe-C Composites

Metal matrix composites exhibit excellent comprehensive properties because of bringing the comprehensive character of matrix material and reinforcement particle into play. It is, therefore, of interest to research the excellent comprehensive properties and application of metal matrix composites for aerospace and automotive. Composites with aluminum and magnesium matrices have been investigated and applied extensively in these fields, while less work has been carried out on iron matrix composites because of their high melting point, large density, small specific strength and very complex processing. Working condition of roller rings used in finishing roll sector or pre-finishing roll sector of high speed line or rod rolling mill production line is extremely vile. The roller rings require not only high strength, but high wear resistance for working layer of the roller rings under high temperature, high load and high speed sliding friction besides the expensive cost of changing the roller rings. Therefore, probing a low-cost roller ring with high life and excellent comprehensive properties under high temperature, high load and high speed sliding friction to replace WC Co-Ni sintered hard alloy and/or WC steel sintered hard alloy and high speed steel roller rings used in high speed line and rod rolling mill production line at present, have become a target of people seeking all along.Utilizing the different centrifugal force resulted from difference of density between Fe-C alloy melt and WC_P, a composite structure roller ring, consisting of WCp/Fe-C gradient composites outer working layer and Fe-C alloy core, was fabricated from a mixture of Fe-C alloy melt and WC_P with centrifugal casting technology in this paper, and a regularity knowledge and the valued achievement were acquired by overall systematic analysis and investigation on the composite structure roller rings.On the basis of analyzing the law of movement and distribution of foreign adding particle in metal melt, the theoretic model of movement and distribution of foreign adding WC_P in Fe-C alloy melt were established under centrifugal field. The movement and distribution of foreign adding WC_P in Fe-C alloy melt are investigated on theory. Therewithal, the microstructure, properties, interface structure, fracture and wear behavior of the gradient composites were investigated by optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffractometer, AG-1 250kN universal tensile test machine and MMS-1G high velocity wear testing machine.A composite structure thick-walled rings, consisting of a WC_P/Fe-C gradient composites outer layer of 20-30 mm heavy-section and Fe-C matrix alloy core, was successfully obtained by centrifugal casting method at 600-1400rpm, dimensioned by outer diameter 164-292mm, inner 78-140mm, highness 74-100mm. Analysis and investigations on the thick-walled ring specimen showed that the results of computer simulation, in term of the movement and distribution model of WC_P in Fe-C alloy...