Parameter optimization for ultrasonic-assisted grinding of γ-TiAl intermetallics: A gray relational analysis approach with surface integrity evaluation

Abstract

The processing of γ-TiAl intermetallic compound (Ti–45Al–2Mn–2Nb) is essential for manufacturing aircraft engine components, known for their challenging machinability. This study delved into the machining performance of γ-TiAl intermetallic compound through ultrasonically assisted grinding experiments. Various grinding parameters, such as wheel rotation speed (v s), feed rate (v w), depth of grinding (a p), and ultrasonic amplitude (A), were investigated to understand their effects on grinding forces, temperatures, and surface quality. Gray relational analysis (GRA) and analysis of variance were used to analyze experimental data and ascertain the optimal machining parameters for ultrasonically assisted grinding of γ-TiAl intermetallic compound. Additionally, post-processing surface integrity, encompassing surface roughness, morphology, and residual stresses, was evaluated. The optimal grinding parameter combination was determined as F n = 3.22 N, F t = 1.08 N, and T = 174°C through GRA. Under the selected machining conditions, the depth of cut exerted the most significant influence on the grinding force and temperature, while the effect of wheel speed was the weakest. The surface roughness (Ra) of the workpiece increased with increasing feed rate and depth of the cut but decreased gradually with increasing wheel speed. Upon applying ultrasonic vibration, there was a notable decrease in surface roughness, ranging from 20.12 to 7.67%. However, the increase in the wheel speed, depth of cut, and feed rate inhibited the reduction of roughness due to ultrasonic vibration. Ultrasonic vibration effectively reduced the profile height of the workpiece surface, with a maximum reduction of 1.94 μm within the selected range. Nonetheless, as the wheel speed, depth of cut, and feed rate increased, the effectiveness of this reduction gradually diminished.