On the diffusion wear of cemented carbides in the turning of AISI 316L stainless steel

The present work has studied the wear and wear mechanisms of three different but comparable cemented carbide grades during orthogonal turning of AISI 316L. The influences of WC grain size and cuffing speed on the resulting crater and flank wear have been evaluated by optical surface profilometry and scanning electron microscopy (SEM). The mechanisms behind the crater and flank wear have been characterized on the sub-micrometer scale using high resolution SEM, energy dispersive X-ray spectroscopy (EDS), Auger electron spectroscopy (AES) and time of flight secondary ion mass spectrometry (ToE-SIMS) of the worn cutting inserts and the produced chips. In addition to a dependence on cutting speeds, wear rates were also found to be dependent on the WC grain size. High resolution SEM, AES and ToF-SIMS analysis of the worn cemented carbide within the crater and flank wear regions revealed that the degradation of cemented carbide at higher cutting speeds is mainly controlled by diffusion wear of the WC-phase. This is supported by ToF-SIMS analysis of the back-side of stainless steel chips which reveals the presence of a 10 nm thin W-containing oxide film. The results are discussed and interpreted in the light of the conditions prevailing at the tool-chip interface.