Performance Analysis of NbC-based Cutting Materials for dry cylindrical Turning of Carbon Steel

Niobium carbide (NbC) is considered an alternative to conventional tungsten carbide (WC) cutting tool materials for steel machining. Due to its high hot hardness and low solubility in metallic matrices at elevated temperatures, NbC is a promising cutting tool material for high-speed cutting applications where wear resistance and process stability are essential. In this context comparative investigations on the cutting performance of a laboratory-produced uncoated NbC cutting tool material have been carried out. The investigated cutting tool material composition NbC-12Ni4Mo5VC was developed at the Federal Institute for Materials Research and Testing (BAM). A comparative analysis of the application behavior of NbC-based cutting tools and industrial reference tungsten carbide WC-6Co tools has been conducted. Dry cylindrical turning tests were carried out for machining carbon steel C45E. The tests involved varying the cutting speed from vc = 50 m/min to 200 m/min in order to analyse the application characteristics of both cutting tool materials under increasing thermal load. Tool wear and workpiece surface quality were assessed using maximum flank wear width VBmax, crater depth KT and surface roughness Ra as evaluation criteria over a defined material removal Vw. The NbC-based cutting tools demonstrated equivalent or improved performance, particularly at a higher cutting speed of vc = 200 m/min in comparison to the WC-6Co tools. Notably, crater depth KT and maximum flank wear width VBmax have been reduced while surface roughness Ra remained consistent. These favourable differences in wear behavior highlight the capability of NbC-based cutting materials for industrial applications.