Tatarkina I. Improving of service properties of lifetime defining parts and technological characteristics of materials by surface modification including nanostructuring

The influence of surface treatment on the properties of the products is analyzed in this thesis. It was determined that the character and the value of the property changes in the surface treatment depend on three factors - the genesis of the surface layer, its thickness in relation to the area and the surface area of the item to its volume (A). Thermo-chemical treatment results in that the item getting brittle due to layer rigidity. After machining the surface roughness and cold hardening play a decisive role. Ion bombardment (IB) in addition to defect healing creates a modified layer with thickness about 1 mkm with a special bimodal structure which has higher deformability and controls the behavior of the deforming body without changing the characteristics of the core. The effect depends on A that characterizes the role of surface in property changes. If A < 1 the hardening is predominate without loss of ductility. If A > 1 plastification is realized. Applying Epilam (EP) leads to defect healing but does not lead to strengthening. If A  < 1 it does not influence on properties, if A > 1 it significantly increases flexibility. The fatigue life increases in several times because of defect healing after IB and EP. The plastification of steel sheets by EP and IB was proposed to enhance the ability to extract of thin steel sheets. So far there was no way to influence technological plasticity of the prefabricated sheet. The results of the work were tested and adopted for implementation.