Surface finishing and enhancement of Ni-based alloy using sliding burnishing with active rotary tool

The burnished surface quality of a Ni-based alloy was investigated. For this, we developed and utilized a sliding burnishing process with an active rotary diamond-like carbon-coated carbide tool. Two kinds of Ni-based alloys subjected to solution heat and aging heat treatments were used as workpiece materials. The burnished surface quality was evaluated based on the roughness and profile of the surface, hardness, and the microstructure of the subsurface, residual stress, and full-width at half maximum based on X-ray analysis, and bending property of the testpiece. The preliminary surface, which was finished by filing, was also evaluated for comparison. A smooth-finished surface of approximately Ra = 0.1 mu m or less was obtained by the burnishing process in both materials. The subsurface hardness of the solution heat-treated material was increased by the burnishing process, and it was also observed to increase with the thrust force as a burnishing condition, while the influence of the burnishing process on the subsurface hardness at a depth of 20 mu m or more from the surface was hardly observed in the aging heat-treated sample. A large compressive residual stress and the full-width at half maximum can be obtained for the burnished surface. Based on the three-point bending test using the solution heat-treated material, the yield load transitioned from the elastic to the plastic region increased and the bending strength also clearly increased due to the burnishing process for a thrust force of 100 N. The developed sliding burnishing process with diamond-like carbon-coated carbide tool can yield a high-quality surface with low roughness, high hardness, and large compressive residual stress of Ni-based alloys based on solution heat treatment and aging heat treatment, respectively.