Positional Dependence of Material Removal and Abrasive Wear in Single Abrasive Grain Grinding of Turbine Disk Mortises

FGH99 powder high-temperature alloy, owing to its excellent strength at elevated temperatures, has emerged as a promising candidate for turbine disk mortises in aircraft engines. Form grinding enables high-precision machining of mortises; however, the complex curved profile leads to variations in abrasive velocity, cutting thickness, and motion modes at different locations, making it difficult to ensure surface quality. In this study, single-abrasive-grain grinding experiments were conducted at six typical mortise positions to clarify the mechanisms of material removal and abrasive wear. The scratch morphology, pile-up ratio, subsurface metallographic structure, and abrasive wear characteristics were systematically examined. Results indicate that during bevel grinding, lateral displacement of abrasives enlarges scratch width and increases the pile-up ratio, thereby reducing material removal efficiency. Subsurface analysis revealed that grains on the high pile-up side exhibited more severe fracture and dislocation. Regarding process parameters, increasing grinding speed reduced the pile-up ratio, which stabilized above 20 m/s; with increasing single-grain cutting thickness, the pile-up ratio first increased and then decreased, reaching a maximum at 0.3 µm. In terms of wear behavior, abrasive grains in highly curved regions experienced more severe wear, and macro-fracture occurred more readily when the rear edge of the grain acted as the cutting edge. These findings reveal the positional dependence of material removal and abrasive wear in mortise form grinding, and provide theoretical guidance for process optimization in turbine disk machining.