Free-cutting steels are developed to produce large quantities of parts with low mechanical\nbehavior, mainly for automotive sector. These alloys contain phosphorous, lead, sulfur, and manganese\nthat help to improve the machinability and surface roughness. However, due to the toxicity of lead,\nsteel mills in recent years have been focusing on non-toxic steels to produce minimum environmental\npollution and better machinability. The present work investigates the tool wear during dry and\nwet turning of free-cutting steels (SAE 1212, SAE 12L14, and SAE 1215) by using uncoated hard\nmetal inserts at three cutting speeds. Additionally, a EDS analysis was performed to determine the\npresence of Mn and S elements at the rake face of the cutting tool that can induce a higher adhesion of\nmanganese sulfide (MnS). The results show that the SAE 12L14 steel has the best performance in\nterms of tool life at different cutting speeds. This difference is maximum at the lowest cutting speed,\nwhich gradually decreases with the increase of the cutting speed. The wear behavior is evaluated\nin the three steel alloys at each cutting speed and, consequently, the tool wear exhibits a slightly\nbetter performance in the dry machining condition for higher cutting speeds (180 and 240 m/min),\nindependent of the steel alloy. Finally, EDS analysis confirms the presence of Mn and S elements at\nthe rake face of the inserts machined in dry condition. Hence, MnS is expected to interpose between\nthe machined surface and cutting tool surface to behave similar to tribofilm by reducing the wear on\nthe cutting edge.
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