1- Associate professor, Department of Mechanical Engineering, Engineering Faculty, Central Tehran Branch, Islamic Azad University, Tehran, Iran , saeed_dinarvand@yahoo.com
2- Assistant Professor, Department of Mechanical Engineering, Engineering Faculty, Central Tehran Branch, Islamic Azad University, Tehran, Iran
Abstract: (1128 Views)
In the current research, the effect of cutting depth and speed on surface topography, microhardness and microstructural changes in cross-sectional surface of turned parts under dry, wet, MQL and cryogenic cooling (CO2) conditions, on 304L stainless steel has been investigated. The main origin of surface topography defects was the formation of built up edge (BUE) on the cutting tool and its removal again. Also, the increase in cutting speed causes instability in the formation of BUE, as a result the volume of accumulated BUE decreases. Considering the improvement of surafce topography, in the order of priority, the efficiency of MQL, wet and cryogenic methods has been from the highest to the lowest compared to the dry method. the cross section of machined samples were prepared and it was observed that subsurface hardness of the samples decreases with the distance from the surface up to 34% and approaches the hardness of the bulk material. The hardness value in cross section of machined samples is directly related to the work hardening caused by severe plastic deformation on machined surface.With increase of cutting speed, the intensity of plastic deformation increases and the hardness under the surface increases. Different cooling and lubrication processes have a direct effect on thickness of the microstructural deformed layer. Under the highest value of cutting speed used in this research, the maximum reduction in thickness of the deformed layer of the microstructure in cryogenic and MQL conditions compared to the dry mode was equal to 62% and 28%, respectively
Article Type:
Original Research |
Subject:
Machining Received: 2023/09/26 | Accepted: 2023/11/2 | Published: 2023/11/1