Study on the edge defects of high volume fraction 70% SiCp/Al composites in ultrasonic-assisted milling

Abstract

Directing at the hard machinability of high volume fraction 70% SiCp/Al composites， a longitudinal and torsional ultrasonic-assisted milling method is proposed to improve the edge quality and machining efficiency. By observing the metallographic structure of the material, the three-dimensional finite element model of SiC particles with spherical, ellipsoidal and random polyhedra is established and analyzed by ABAQUS simulation software. The formation mechanism of edge defects, stress distribution, defect characteristics and the effect of machining parameters on milling force are investigated during ultrasonic-assisted milling. The results show that the edge defects appear at the inlet, outlet and middle edge position, especiallyis more serious at the outlet position. The SiC particles failure modes mainly include particle pullout, particle shearing, crushing, and the edge defects mainly include matrix tearing, edge breakage, burrs, bulgesandpits. In a certain range of ultrasonic amplitude, ultrasonic-assisted milling can effectively reduce the surface fragmentation rate and milling force, slow down the expansion of cracks, increase the plastic flow of material, and obtain better edge quality compared with traditional machining method. By comparing the results of finite element simulation and experimental tests, it shows that the simulation results are in good agreement with the experimental tests.

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