Influence of cubic boron nitride grinding on the fatigue strengths of carbon steels and a nickel-base superalloy

The influence of cubic boron nitride (CBN) grinding on fatigue strength was investigated on an annealed carbon steel, a quenched and tempered carbon steel at room temperature, and a nickel-base superalloy, Inconel 718, at room temperature and 500 degrees C, The results were discussed from several, viewpoints! including surface roughness, residual stress, and work hardening or softening due to CBN grinding. The fatigue strength increased upon CBN grinding at room temperature. primarily because of the generation of compressive residual stress in the surface region. Hen-ever, in the case of Inconel 718, this marked increase in the fatigue strength tended to disappear at the elevated temperature due to the release of compressive residual stress and the decrease of crack growth resistance at an elevated temperature.