Modeling of surface hardening and roughness induced by turning AISI 4140 QT under different machining conditions

For this work, the surface-layer states of turned AISI 4140 QT were investigated by means of surface roughness and microhardness measurements. Different machining conditions are regarded, namely cutting velocity, feed rate, tool wear and the tool corner radius, as well as the tempering state of the workpiece. The resulting data is analyzed by multiple algorithms, in order to create analytical models for a real time process control. Modeling approaches applied are linear regression, stepwise regression, LASSO and Elastic Net. Finally, the models are evaluated in terms of quality, complexity and physical plausibility.