AbstractThe effect of high cutting speed and feed rate on the surface integrity of AISI 4340 steel during a finishing turning operation was investigated. The experimental work involved the determination of residual stress distribution in the surface region, microhardness variation of the surface region, and the examination of surface and subsurface using both optical and scanning electron microscopy. The residual stresses were found to be compressive. The microhardness in the surface region varied little and was the same as that of the bulk material. In general, the appearance of the surface was similar to those reported for low cutting speeds as recommended for machining the same type of steel.MST/998