Influence of microstructure on wear behaviour of uncoated WC tools in turning of Alloy 718 and Waspaloy

Artikel i vetenskaplig tidskrift, 2012

The effect of grain size in wrought Alloy 718 and Waspaloy on the wear of cemented carbide tools was examined by measuring the progression of wear in a specific transverse turning operation. Work material with different microstructure was achieved through heat treatments of the material from a single batch, for each alloy. The worn cutting tools were analysed by means of scanning electron microscopy and X-ray microanalysis to study the wear mechanism. The grain size of the work material in relation to undeformed chip thickness is found to control the depth of cut (DOC) notch wear, which is the tool life limiting factor when machining the work material with large grain size. The adhesive wear is shown to dominate on the rake face, but this wear is not tool life limiting since the cladding of work material to the tool surface basically protects the tool from further wear. Concerning the flank wear, machining of Waspaloy is associated with less such wear than machining of Alloy 718 irrespective of grain size. The analysis shows that higher cutting forces and expected cutting resistance due to higher work to fracture cannot explain the difference in flank wear. Instead, from the analysis of the oxidized surface below the flank wear it is supposed that the difference in tribological conditions is an important factor for flank wear development.