Tribological Characterization of Steels for Cutlery: A New Methodology to Access Cutting Edge Sharpness

In this work, the tribological behaviour of stainless steel used in cutlery is analysed. Professional knives were tested in well-controlled field conditions and the mechanism of cutting edge loss of sharpness was determined by using Scanning Electron Microscopy. It was determined that the mechanism which causes loss of sharpness in the cutting edge is plastic deformation whereas the edge life itself is mainly affected by abrasive wear during the resharpening process and the sliding wear that occurs while the knife is being used. A new methodology based on the energy that causes plastic deformation is proposed in order to access the bending resistance of the cutting edge. The proposed technique is very simple and cost effective. It reproduces to a great extent the field mechanisms that cause the loss of sharpness in the cutting edge and allows the ranking of different stainless steels usually used by the cutlery industry. Additionally, abrasive and sliding wear tests were carried out on martensitic and ferritic stainless steels. Although the chemical composition and heat treatment considerably modified the microstructure and hardness of the steels, they had no significant effect on abrasion resistance and friction coefficient. On the other hand the sliding wear rate was greatly affected by the chemical composition of the steel.