Residual stresses and surface roughness are held to be the primary factors influencing ; resistance of metals. While the relationship between turning parameters and surface roughness is well known, little has been published on the influence of these parameters on the residual stresses. The paper presents an experimental study of the influence of turning parameters on residual stresses. Two steels commonly used in the production of shafts (UNI-ISO C45 and UNI-ISO 39NiCrMo3) were machined by turning, and the results of variations in four process parameters were measured and analysed. An X-ray diffractometer was used to measure residual stresses. The obtained data were analysed, showing that the relationships between the investigated turning parameters and residual stresses is the same for both steels, and that residual stresses are influenced mainly by the feed rate and the nose radius; while the cutting velocity and the primary rake angle play a minor, negligible role. An empirical model identified that can be used to predict residual stresses as a function of the two major I parameters. These models can be used to optimise the turning conditions of components when their functionality requires the control of residual stresses and surface roughness. Moreover, in order to investigate the residual stress generation mechanism, a regression analysis was performed between residual stresses and the cutting forces, hypothesising that the forces can provide important information on the stress field generated during turning. Results show that the cutting forces cannot be directly related to the mechanism of residual stresses generation, as the friction forces between chip and tool face tend to mask the information on the stress field.
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