Experimental study on surface finish and tool wear in ultrasonic vibration-assisted milling of nickel-based single-crystal superalloys

Abstract

Nickel-based single-crystal superalloys have emerged as the primary materials for a new generation of aero-engines, courtesy of their remarkable high-temperature performance, oxidation resistance, microstructure stability, and thermal fatigue resistance. Nevertheless, due to its inherent traits of high hardness and low thermal conductivity, the cutting performance is rather poor. In light of this, ultrasonic vibration and minimum quantity lubrication techniques are incorporated in this paper to assist in milling nickel-based single-crystal superalloy DD5 with the aim of improving the cutting quality and reducing tool wear, The findings reveal that under dry cutting conditions, although the surface roughness of ultrasonic vibration-assisted milling (UM) marginally escalates compared to that of conventional milling (CM), the surface defects are mitigated, and the scratch situation on the back of the chip is significantly alleviated. Moreover, as the cutting speed increments, the chip thickness diminishes. In contrast to UM and CM under dry cutting conditions, the thickness of the subsurface heat-affected layer after minimum quantity lubrication ultrasonic vibration assisted milling (UMQL) is the slightest at 2.0 μm, and in the UM processing under dry cutting conditions, as the cutting speed rises, the thickness of the affected layer marginally reduces. In the CM and UM processes under dry cutting conditions, tool failure occurred when the milling length reaches 0.9 m and 1.3 m respectively. Owing to the efficient cooling and lubricating effects of UMQL, when UMQL is employed for processing, the milling length of the tool can extend up to 2.1 m.