The Chip Formation Mechanism for the Machining of the EN8 Unalloyed Steel

The EN8 carbon steel (unalloyed) was machined at different machining conditions in a lathe. The Indoloy IK-20 tungsten carbide tool was used for the dry turning of the material. The true stress–true strain curve for the material was obtained and the stress–strain relationship was obtained as σ = 850.48εⁿ. The von Mises stresses (VMSs) were determined for different experimental parameters. The collected chips for all the machining conditions were examined under the scanning electron microscope (SEM). The mechanism of chip formation was identified by observing the SEM images for the chips. The mechanism was further established with reference to the extent of von Mises stress generation. The mechanism of chip formation depends upon the experimental parameters. The machining chips were formed by successive lamellar shear sliding with and without the presence of dislocation. The von Mises stress increases during the lamellar shear sliding chip formation at the higher strain rate. The chip formation was influenced by the crack formation at higher speed and feed to reduce the level of von Mises stress.