Effect of Textured Dentated Surfaces on 30KhGSA Steel Damage and Life at Fatigue, Fretting Fatigue, and Fretting

Machines and constructions are noted to contain components, units, and assemblies, which are joined together, forming a large number of contacting pairs. At operating loads, the latter become sources of material damage as a result of fretting fatigue and fretting wear. The safety and long-term operation of those items would require studies on the nature of these processes and search for the methods of reducing their intensity. Investigation results for the effect of textured surfaces in the form of a dent (recess) network and electric-spark VK8 alloy embedding over 30KhGSA steel specimen surfaces on fatigue, fretting fatigue, and fretting wear characteristics are presented. The dent network is formed by plastic indentation using a specially developed device. This process initiates residual tensile stresses. Their optimization was carried out with computation-experimental correlation between the geometrical ratios of dent network parameters (spacing between dent rows, in-row spacing, dent depth). Discrete VK8 alloy-embedded surfaces were generated with the electric-spark method, providing optimum process parameters. Textured surfaces reduce fatigue and fretting fatigue resistance, while enhancing the fretting wear one in comparison with smooth surfaces. Additional treatment of the textured dentated surface with the ion-plasma thermocyclic nitriding method greatly increases the fatigue and fretting fatigue resistance of 30KhGSA steel. Electric-spark VK8 alloy embedding results in worse fatigue and fretting fatigue properties, which is determined by the surface formation technology and difference between embedded particle and base metal characteristics.