Modification by composite coatings of knives made of low alloy steel for wood machining purposes

Low alloy steel (LAS) is a commonly used material for producing knives in wood and pulp industry. In some application specific advantageous features of LAS make it impossible to replace it by other harder and more resistant to abrasion materials such as: HSS, carbide or stellites. The aim of this study was to improve the resistance to wear of knives’ edges made of LAS covered with composite coatings (duplex coatings). This method is based on low temperature ion nitriding, when effects of the modification are intensified with deposition of hard films on pre-nitrided knives’ surfaces. The results of the research show that composite modification with CrXN film deposited on pre-nitrided surfaces enables improving the knives’ resistance to wear. The CrXN hard film gives an added improvement effect to the wear resistance of nitrided knives. The toolʹs service life in fast wear tests rises more than 2.5 times. The modification of knives’ edges also improves their resistance to shocks caused by the dynamic forces active during the cutting process.