High-speed Machinability And Machining Failure Removal Mechanisms Of SiC_p/Al Composites

The SiC_p/Al composite,as a type of particle-reinforced metal matrix composite,has high specific strength and specific modulus,excellent electrical and thermal conductivity,and wear resistance,and its light weight and high strength characteristics make it have a broad application prospect in aerospace,defence and military,electronic packaging,and so on.However,while its application in high value-added fields is indispensable for precision machining,there are still technical limitations of high machining cost and poor surface quality in the machining of SiC_p/Al composite material.With the advancement of machine tool technology in recent years,the application of high-speed machining technology is gradually becoming widespread,which provides a new technical means for the precise and efficient processing of this material.This paper investigates the high-speed machinability and material removal mechanism of SiC_p/Al composites,so as to provide some theoretical basis for the efficient and precise manufacturing of this material,and the main research contents are as follows:(1)First,the partially cast SiC_p/Al composites were subjected to annealing and T6heat treatments,respectively,and the high-speed orthogonal milling experiments were conducted on the composites with different heat treatments,and the high-speed machinability of the composites was summarized by analyzing the effects of cutting speed and feed on chip morphology,cutting force,cutting energy consumption,surface quality.The results show that the mechanical properties and dynamic response of the composites by different heat treatments show differences,and the machinability under the same machining conditions also has some differences,but they all show that with the increase of cutting speed,the degree of chip continuity decreases,and the cutting force and unit cutting energy consumption decreases.At the same time,the cutting force increases non-linearly with the increase of feed,and the unit cutting energy consumption decreases.The average roughness of the machined surface and machining hardening decrease with the increase of cutting speed and feed.As a result,the SiC_p/Al composites exhibit better machinability under high-speed machining conditions.(2)Secondly,based on the experimentally obtained composites machined surface morphology,particle failure behavior under different tool-particle relative positions was investigated by means of finite element simulation to investigate the formation of surface defects such as pits,scratches,particle fragmentation and matrix tears on the surface.It was shown that SiC particle failure is the formation and expansion process of microcracks.The differences in stress fields and tool-particle contact force at different tool-particle relative positions are important reasons for the different failure behaviors of the particles.(3)Finally,the dynamic chip formation process and stress-strain field were analyzed by establishing a finite element cutting model which considered the microstructure and material damage of SiC_p/Al composites,and the chip formation mechanism and the machined surface morphology of the composites were analyzed.It is shown that the chip formation process of SiC_p/Al composites involves local shear deformation of the matrix material and SiC particle failure,and the non-homogeneous microstructure of the composites leads to non-homogeneous deformation and stress concentration in the local area.Particle failure is influenced by the tool-particle relative position and matrix material deformation in both direct and indirect modes,and particle failure is an important cause of surface morphological defects of SiC_p/Al composites.and machined surface morphology.