Dry Hard Turning versus Grinding—The Influence of Machining-Induced Surface Integrity on Fatigue Performance

Abstract

Dry hard turning (DHT) provides an effective process for finishing high-hardness materials. Machining-induced surface integrity has a direct impact on functional performance. This study compares the effects of the DHT and grinding processes on machining-induced surface integrity and fatigue performance of 18CrNiMo7-6 steel. The DHT and grinding experiment were carried out by using a polycrystalline cubic boron nitride tool and corundum wheel, respectively. The 3D surface morphology, surface roughness, surface residual stress, and machining accuracy of the hourglass-shaped specimen were measured. The fatigue fracture was characterized by scanning electron microscopy. The experimental results show that compared to grinding, DHT has obtained a larger surface compressive residual stress (the maximum axial and tangent residual stresses are −762.6 MPa and −442.8 MPa, respectively) and a lower surface roughness (the minimum Ra and Rq are 0.172 μm and 0.230 μm, respectively). This study is an attempt to use DHT instead of a grinding process to finish 18CrNiMo7-6 steel, providing a reference for high-quality and sustainable manufacturing of hardened steel.