Abstract:

This study investigated the effect of the radial depth of cut during milling on the machining-induced surface integrity parameters and the subsequent fretting wear performance of FGH99. By maintaining a consistent surface roughness， the synergistic effects of surface hardness and surface residual stress on the fretting wear behavior of FGH99 were analyzed. The results indicate that an increase in radial depth of cut leads to elevated cutting temperatures and cutting forces， consequently altering the surface integrity parameters. As the radial depth of cut increased from 0.06 mm to 0.30 mm， the surface hardness rose from 476.8 HV to 589.2 HV， and the surface residual tensile stress increased from 100.8 MPa to 661.3 MPa. Fretting wear tests revealed that under conditions of low surface hardness and low surface residual tensile stress， wear primarily manifested as plastic deformation and oxidative wear. Conversely， under high surface hardness and high surface residual tensile stress conditions， the detrimental effect of surface residual tensile stress on wear outweighed the beneficial effect of increased surface hardness， leading to a composite wear mechanism involving oxidation， abrasion and fatigue. When the radial depth of cut is in the range of 0.12 to 0.18 mm， an optimal balance between surface hardness and surface residual tensile stress was achieved， leading to the best fretting wear resistance of the milled FGH99 surface

Key words: powder metallurgy superalloy, milling, surface hardness, surface residual stress, fretting wear