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Micromilling (MM) is favored by the field of high-precision micro parts. However, the high plasticity of Inconel718 often poses a threat to MM, such as pits, humps, and gullies, which affect the surface quality. In this study, the influence of ultrasonic vibration-assisted micromilling (UVAMM) on surface quality is comprehensively analyzed by using the machining process of workpiece vibration, combined with cutting force, tool wear, surface texture, and corrosion resistance. The results show that small amplitude plays a significant role in reducing cutting force and inhibiting tool wear. The better surface quality is obtained by optimizing cutting parameters (the cutting speed (vc) is 37.68 m/min, the feed per tooth (ƒz) is 3 μm/z, and the amplitude (A) is 6 μm), which is a uniform and regular fish scale surface with lower surface roughness and fewer surface defects. Furthermore, the application of ultrasonic vibration also significantly improves the surface corrosion resistance of Inconel718. It is worth noting that the surface corrosion resistance does not completely depend on the surface roughness, but also has a close correlation with the surface texture. [ABSTRACT FROM AUTHOR]

In the traditional micromilling (TMM) of Inconel718 alloy, due to the influence of material plasticity and size effect, relatively large burr will be produced. In order to hinder the burr forming in micromilling, ultrasonic vibration in feed direction is applied to the workpiece to complete vibration cutting. Combined with trajectory simulation and cutting experiment, the burr formation mechanism of TMM and ultrasonic vibration assisted micromilling (UVAMM) was studied. The results show that when the ratio of amplitude (A) to feed per tooth (ƒz) is greater than 0.5, continuous cutting changes to intermittent cutting in the vibration cutting process. The fractured area with dimples on the burr increases with the increase of amplitude. Compared with TMM, UVAMM improves chip breaking ability, facilitates the propagation of burr crack, and effectively inhibits the formation of burr. When the chip breaking condition is reached, the burr shape is usually tearing or flocculent. Under the conditions of low speed (n), large ƒz, and large A, the burr suppression is more obvious. [ABSTRACT FROM AUTHOR]

(Ti,W)C-based cement tool materials with c-BN particles as additive phase are fabricated by the hot press sintering. The effect of c-BN addition on the microstructure and mechanical properties of (Ti,W)C-based cement tool materials are investigated. With the addition of c-BN, the fracture mode of composite transform from intergranular to transgranular fracture. The main toughening mechanism is particle bridging, crack deflection and crack bifurcation, which improve the fracture toughness of cement tool material. The proper addition of c-BN can improve the mechanical properties of the composites. When the content of c-BN is 1.5 wt %, (Ti,W)C-based cement tool materials reaches the optimum comprehensive mechanical properties. The hardness, the flexural strength and the fracture toughness is 19.78 GPa, 987 MPa and 9.44 MPa m1/2, respectively. [ABSTRACT FROM AUTHOR]