Study on surface damages caused by turning NiCr20TiAl nickel-based alloy

The machined surface damages were investigated after NiCr20TiAl nickel-based alloy was turned in the various cutting conditions. It is found that the plastic deformation and carbide particles of NiCr20TiAl alloy are responsible for the machined surface damages during turning. When the carbide particles are removed from the machined surface during machining, the residual cracks inside surfaces are linked together due to a steep rise in the shear stress, which results in the surface cavities and plucking. The slip zones are formed inside the machined surfaces because the dislocation movement is inhibited by many grain boundaries of NiCr20TiAl alloy during machining, and a work-hardening layer with a non-uniform depth is produced. At the cutting speed of 100 m/min, feed of 0.15 mm/r and depth of cut of 1 mm, a relatively smooth surface with the thinner work-hardening layer is generated owning to the reduced cutting force.